Testing And Adjusting

Usage:

Introduction

NOTE: For Specifications with illustrations, make reference to Specifications For 3100 HEUI Diesel Truck Engine. If the Specifications are not the same as in the Systems Operation, Testing and Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.

Troubleshooting

Troubleshooting can be difficult. The Troubleshooting Index gives a list of possible problems. To make a repair to a problem, make reference to the cause and correction on the pages that follow.

This list of problems, causes, and corrections will only give an indication of where a possible problem can be, and what repairs are needed. Normally, more or other repair work is needed beyond the recommendations in the list.

Remember that a problem is not normally caused only by one part, but by the relation of one part with other parts. This list is only a guide and cannot give all possible problems and corrections. The serviceman must find the problem and its source, then make the necessary repairs.

See Electronic Troubleshooting, 3100 HEUI Diesel Truck Engines, SENR6566, for troubleshooting the Electronic Control System for logged or active diagnostic codes. Using the diagnostic code for troubleshooting will simplify the process. The diagnostic code will lead you to a mechanical or electrical problem more efficiently.

Troubleshooting Problem List

1. Engine Crankshaft Will Not Turn When Ignition Switch Is On

2. Engine Hard To Or Will Not Start (Engine Crankshaft Turns Too Slowly)

3. Engine Cranks But Will Not Start (Engine Crankshaft Turns Freely)

4. Engine Misfiring Or Running Rough

5. Engine Stall At Low RPM

6. Low Power

7. Too Much Vibration

8. Loud Combustion Noise (Sound)

9. Valve Train Noise

10. Oil In Cooling System

11. Mechanical Noise (Knock) In Engine

12. Fuel Consumption Too High

13. Too Much Valve Lash

14. Little Or No Valve Lash

15. Oil At The Exhaust

16. Engine Has Excessive Early Wear

17. Coolant In Lubrication Oil

18. Too Much Exhaust Smoke (Black Or Gray)

19. Too Much Exhaust Smoke At Normal Operating Temperatures (White/Black Or Blue Smoke)

20. Engine Has Low Oil Pressure

21. Engine Uses Too Much Lubrication Oil

22. Above Normal Coolant Temperature

23. Below Normal Coolant Temperature

24. Exhaust Temperature Too High

25. Starting Motor Does Not Turn

26. No Charging Current, Or Low Or Irregular Charging Current

27. Alternator Charge Too High

28. Alternator Has Noise

29. Fuel In Lubrication Oil

30. Fuel In Coolant

31. Loss Of Coolant

32. Air Inlet Heater (If Equipped)

33. Soot In The Inlet Manifold

34. Air In Fuel

35. Hydraulic Troubleshooting

Troubleshooting Problems

Problem 1: Engine Crankshaft Will Not Turn When Ignition Switch Is On.

Probable Cause(s):

* Battery Has Low Output

* Wires Or Switch Has Defect

* Starting Motor Solenoid Has Defect

* Starting Motor Has A Defect

* Internal Problem Prevents Engine Crankshaft From Turning

* Problem With Accessory Equipment

1. Battery Has Low Output:

Check condition of battery. Charge battery or make replacement as necessary (refer to Special Instruction SEHS7633, for Battery Test Procedure). Load test batteries (refer to Special Instruction SEHS9249, for use of 4C4911 Battery Load Tester.

2. Wires Or Switch Has Defect:

Make Reference to Problem 25: Starting Motor Does Not Turn.

3. Starting Motor Solenoid Has A Defect:

Make Reference to Problem 25: Starting Motor Does Not Turn.

4. Starting Motor Has A Defect:

Make Reference to Problem 25: Starting Motor Does Not Turn.

5. Internal Problem Prevents Engine Crankshaft From Turning:

If the crankshaft cannot be turned after disconnecting the transmission and/or the power take-off, remove the unit injectors and check for fluid in the cylinders while turning the crankshaft. If fluid in the cylinders is not the problem, the engine must be disassembled to check for other internal problems. Some of the possible problems are bearing seizure, piston seizure, and valves making contact with the pistons.

NOTE: Refer to Disassembly And Assembly, SENR6553, for the proper procedure for unit injector removal and installation.

6. Problem With Accessory Equipment:

Check driveline for free movement. Disconnect or remove PTO drive(s). Remove and inspect engine accessories that may lock up the engine (air compressor, power steering pump, lubrication oil pump, hydraulic oil pump, etc). Repair or replace any accessory that is binding or has seized.

Problem 2: Engine Hard To Or Will Not Start.

(Engine Crankshaft Turns Too Slowly).

Probable Cause(s):

* Battery Has Low Output

* Starting Motor Has A Defect

* Oil Too Thick

* Internal Problem Prevents Engine Crankshaft From Turning

* Problem With Accessory Equipment

1. Battery Has Low Output:

2. Starting Motor Has A Defect:

Make Reference to Problem 25: Starting Motor Does Not Turn.

3. Oil Too Thick:

a. Use the recommended Lubrication Viscosities as stated in the Operation And Maintenance Manual. If the oil is changed then replace with the oil viscosity recommended and replace oil filter(s).

b. Determine if maintenance intervals are correct for the service application and if they are being followed. If they are, and the oil quality has deteriorated an oil sample should be sent out for analysis.

4. Internal Problem Prevents Engine Crankshaft From Turning:

5. Problem With Accessory Equipment:

Problem 3: Engine Cranks But Will Not Start.

(Engine Crankshaft Turns Freely).

Exhaust Smoke Cannot Be Seen While Starting (Go to Step 1)

Probable Cause(s):

* Fuel Supply Or Engine Oil Supply Low

* No Power To ECM

* Software Problem

* No Speed/Timing Signal

* Fuel System Problem

* Incorrect Injection Actuation Pressure

* Slow Cranking

Exhaust Smoke Can Be Seen While Starting (Go to Step 8)

Probable Cause(s):

* Cold Outside Temperatures

* Low Fuel Pressure

* Air In Fuel

* Loss Of Compression

* Water In Fuel

1. Fuel Supply Or Engine Oil Supply Low:

Check that there is a sufficient fuel supply to operate the engine and the engine oil level is at the desired level. Engine oil feeds the high pressure hydraulic pump.

2. No Power To ECM:

a. Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Voltage Supply To The ECM Test.

b. Check for presence and correct installation and operation of aftermarket engine shutdown devices (not installed by Caterpillar). These devices usually interrupt power to the ECM.

c. Check the ECM power and ground circuits and connections. If battery voltage does not reach the ECM, wire a bypass circuit for power and ground as shown in "Battery Circuits Test" in the 3100 HEUI Electronic Troubleshooting Guide, SENR6566.

3. Software Problem:

a. Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566.

NOTE: A new ECM comes with an unprogrammed Personality Module in it. If the ECM has been replaced, the ECM WILL NOT COMMUNICATE and the ENGINE WILL NOT START until the integral Personality Module has had software flashed into it.

4. No Speed/Timing Signal:

a. While cranking the engine, observe engine rpm on a status screen of the EST. If the rpm reads 0 (zero) while cranking, there is a problem in the speed/timing circuit, or the engine cranking speed is below 100 rpm. At least 100 RPM is required to achieve reliable starting.

b. The cranking speed is typically 100 to 150 rpm with a cold engine. A cranking speed of 100 rpm or greater should create enough hydraulic oil pressure to operate the unit injectors. If cranking speed is below 100 rpm, refer to Problem 2: Engine Cranks But Turns Too Slowly. If cranking speed is above 100 rpm then use an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine, SENR6566, for Engine Speed/Timing Circuit Test.

5. Fuel System Problem:

a. Make sure that the engine is not out of fuel and verify that the fuel system is primed. Check engine fuel pressure while cranking. At 200 rpm pressure should read about 275 to 350 kPa (40 to 50 psi), measured at the inlet to the secondary fuel filter. At low idle, fuel pressure should be about 400 to 435 kPa (58 to 63 psi). If fuel pressure is zero then check to see that the cam/timing gear is turning the fuel pump. If fuel pressure is low then check fuel filters, fuel lines, etc. for restrictions. Check fuel transfer pump, valves and bypass. If the fuel system has been worked on, verify that the orificed check valve is mounted correctly on the fuel return line and is working, and that the correct orifice is installed.

b. Check for air in fuel by installing a 2P8278 sight glass on the return line. If access to the rear of the engine is restricted, install the sight glass on the return line at the tank. Check fuel transfer pump fittings and joints for air leaks. Check the unit injectors and sleeves for combustion gas leaks. Remove each unit injector and use a magnifying glass to inspect the base of the sleeve. The unit injector may also show evidence of leaking combustion gas.

NOTE: Refer to Disassembly And Assembly, SENR6553, for the proper procedure for unit injector removal and installation.

c. Check fuel quality. Refer to Truck Performance And Driveability Diagnostic Guide, LEBT3477.

d. In cold weather below 0°C (32°F), make sure that winter grade fuel is being used. Check for waxing in the fuel.

6. Incorrect Injection Actuation Pressure

a. Check dipstick to be sure oil level is normal.

NOTE: Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566 for further diagnostics.

b. Check for air in the system. After opening or working on the high pressure hydraulic oil system, there may be air remaining in the system. To purge the air, crank the engine for thirty seconds at a time at least three times. Allow the starter to cool off for two minutes between each cranking period.

c. Check to see that oil is reaching the hydraulic pump inlet. Inspect the oil supply line from the engine oil gallery on the left side of the engine block to the pump inlet.

d. Check engine oil pressure with a gauge mounted to the oil gallery on the left side of the engine block. There should be about 28 to 55 kPa (4 to 8 psi) while cranking. If there is not any oil pressure then check for dilution of oil (dilution will lower oil pressure), engine oil pump, and pickup.

7. Slow Cranking:

Cranking speed should be a minimum of 100 rpm for engine starting. Refer to Problem 2: Engine Hard To Or Will Not Start.

Exhaust Smoke Can Be Seen While Starting

Probable Cause(s):

8. Cold Outside Temperatures:

a. Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine, SENR6566, for Inlet Heater Driver Open Circuit or Inlet Heater Driver Short Circuit.

NOTE: It is normal to get white smoke while cranking and for a very brief period after starting the engine. For operation in cold and very cold temperatures, a winterfront cover or radiator shutters are recommended.

b. Check to see if the inlet air heater is inoperative. If the INLET AIR HEATER IS INOPERATIVE, then it is permissible to use starting aids such as ether. To repair the inlet air heater, refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566.

Show/hide table

NOTICE

DO NOT USE ETHER IF THE INLET AIR HEATER IS WORKING, as there is possibility of fire or explosion when the ether contacts the heated surfaces.

c. Check fuel grade and quality. If cloud point is too high, waxing may result, plugging the fuel filters and lines. Refer to Truck Performance And Driveability Diagnostic guide.

9. Low Fuel Pressure:

Check fuel pressure with a gauge while cranking. Engine fuel pressure while cranking should read about 275 to 350 kPa (40 to 50 psi) at 200 rpm measured at the inlet to the secondary fuel filter.

10. Air In Fuel:

Check for air in fuel by installing a 2P8278 sight glass on the return line. If access to the rear of the engine is restricted, install the sight glass on the return line at the tank. Check fuel transfer pump fittings and joints for air leaks. Check the unit injectors and sleeves for combustion gas leaks. Remove each unit injector and use a magnifying glass to inspect the base of the sleeve. The unit injector may also show evidence of leaking combustion gas.

NOTE: Refer to Disassembly And Assembly, SENR6553, for the proper procedure for unit injector removal and installation.

11. Loss Of Compression:

Check valve clearances and make adjustments. Refer to the Testing And Adjusting section of this service manual. Low compression can also result from a blown head gasket, piston ring failure, incorrect installation, etc.

12. Water In Fuel:

Condensation may occur in fuel tanks, typically while standing overnight in cool or cold ambient temperatures. The use of a primary filter/water separator is recommended. If water is found in the fuel, it will be necessary to drain fuel tanks, lines and filters and refill with known good fuel of the correct grade, and replace fuel filters.

Problem 4: Engine Misfiring Or Running Rough

Probable Cause(s):

* Cold Outside Temperatures

* Air In Fuel

* Injector Problem

* Hydraulic System Problem

* Water In Fuel

* Low Fuel Pressure

* Throttle Position Sensor/PTO Problem

* Valve Clearances

* Head Gasket

* Mechanical Failure In Cylinder

1. Cold Outside Temperatures:

a. Check to see if the inlet air heater is inoperative. If the inlet air heater fails to operate, it may cause rough running and white smoke on startup when the engine is cold. Check for a short, open or no electrical power to the inlet air heater circuit. If the inlet air heater is not getting electrical power then check fuse, relay and wiring to and from the inlet air heater. For further information, refer to Problem 32: Inlet Air Heater.

b. Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine, SENR6566, for Inlet Heater Driver Open Circuit or Inlet Heater Driver Short Circuit.

2. Air In Fuel:

NOTE: Refer to Disassembly And Assembly, SENR6553, for the proper procedure for unit injector removal and installation.

3. Injector Problem:

a. An injector may fail to operate properly, causing a misfire in that cylinder. Some possible causes; debris in the oil supply, incorrect removal of an injector, mechanical pressure on the adapter section, mechanical pressure on the solenoid, or the solenoid coil may develop a shorted or open circuit.

NOTE: There is no bench test ("pop test") for HEUI injectors available for field testing. The only test for injectors is "on the engine".

b. Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine, SENR6566, for Cylinder Cutout Test.

4. Hydraulic System Problem:

a. Check dipstick to be sure oil level is normal.

NOTE: Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566 for electronic problems and for the hydraulic troubleshooting test.

c. Check for leaks in the high pressure line, fittings between the hydraulic pump and the oil manifold, and inside the valve cover.

5. Water In Fuel:

6. Low fuel pressure:

a. Check fuel pressure with a gauge. Fuel pressure at low idle should read about 400 to 435 kPa (58 to 63 psi), and during normal operating conditions under load, should read between 400 and 525 kPa (58 to 76 psi) measured at the inlet to the secondary fuel filter. Fuel pressure to the cylinder head fuel gallery should be as above, less the pressure differential across the secondary fuel filter. Pressure drop across the secondary fuel filter is typically at least 35 kPa (5 psi) with a new filter. As the filter accumulates deposits, the pressure differential will increase.

b. If fuel pressure at the unit injectors drops to approximately 69 kPa (10 psi) it is possible that misfires will occur. This would typically be a "rolling misfire" that affects all cylinders at random, rather than a consistent misfire on a given cylinder.

c. Check fuel filters and fuel lines for restrictions or plugged. Check for fuel transfer pump or unit injector sleeve failure. Check to see if the orifice check valve is loose, missing from the fuel return line, or if the wrong orifice was installed. If sleeve or O-ring damage is found, replace with new parts as necessary. Refer to Special Instruction, Using the 122-7093 Sleeve Replacement Tool Group, SEHS9120.

7. Throttle Position Sensor/PTO Problem:

NOTE: Momentary loss of the throttle position, cruise control or PTO signal may cause a "speed burp" or brief drop in engine rpm. Intermittent signal loss may be perceived as an "unstable engine" problem.

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine, SENR6566.

NOTE: Throttle position, vehicle speed, brake and clutch switches, and other PTO and cruise control component operations can be viewed in the Display Status screens on the electronic service tool.

8. Loss of Compression:

Check valve clearances and make adjustments. Valve clearances set too tight may cause poor sealing and loss of compression. Refer to the Testing And Adjusting section of this service manual. Low compression can also result from a blown head gasket, or cracks in the cylinder head/engine block.

Problem 5: Engine Stall At Low RPM

Probable Cause(s):

* Fuel Pressure Is Low

* Engine Accessories

* Defect In Unit Injector(s)

* Air In Fuel

* Incorrect fuel grade

* Combustion Gas, Or Water In Fuel

* Loss of pressure in high pressure hydraulic oil system

1. Fuel pressure is low:

Make sure there is fuel in the fuel tank. Look for leaks or bad bends in the fuel line between fuel tank and fuel transfer pump. Look for air in the fuel system. Make sure the fuel filters are clean, then check fuel pressure. Engine fuel pressure while cranking should read between 275 to 350 kPa (40 to 50 psi). At low idle, fuel pressure should read between 400 to 435 kPa (58 to 63 psi), and at normal operating conditions under load, fuel pressure should read between 400 and 525 kPa (58 to 76 psi). If fuel pressure is lower than the above pressure, check the fuel transfer pump and fuel pressure regulating orifice at the fuel return line.

2. Engine accessories:

Check engine accessories for damage and make repair or replacement. If necessary, disconnect the accessories and test the engine.

3. Defect in Unit Injector(s):

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for Injector Solenoid Circuit Test.

4. Air in fuel:

Check inlet fuel line or transfer pump for leaks by installing a sight glass on the fuel return line. Repair as needed or install new components.

5. Incorrect fuel grade:

Check fuel grade. In cold weather below 0.0°C (32°F), make sure that winter grade fuel is being used. Check for waxing.

6. Combustion gas, or water in fuel:

Check unit injector sleeves. Repair as needed or install new components.

7. Loss of pressure in high pressure hydraulic oil system:

Refer to problem 3: Engine hard to or will not start. Engine crankshaft turns freely.

Problem 6: Low Power

Probable Cause(s):

* Dirty Fuel Filters

* Oil Level Too High

* Restrictions And/Or Leaks In Air Inlet System

* Plugged Or Damaged Muffler

* Fuel Pressure Is Low

* Low Quality Fuel Or Water In Fuel

* Defect In Unit Injector(s)

* Valve Adjustment Not Correct

* Turbocharger Has Carbon Deposits Or Other Cause Of Friction

* Air, Water, Or Gas In Fuel

* Defect In Boost Sensor

* Defect In Coolant Temperature Sensor

* Defect In Throttle Position Sensor

* Defect In Injection Actuation Pressure Sensor

1. Dirty fuel filters:

Install new fuel filters.

2. Oil level too high:

Remove dipstick and check oil level. If level is too high, drain oil to bring the oil level to the desired level.

NOTE: An oil sample should be run to find out if the oil level is increasing due to a fuel leak or other engine problem.

3. Restrictions and/or leaks in air inlet system:

a. Check for leaks.

b. Check the pressure in the air inlet manifold. Look for restrictions at the air cleaner. Correct any leaks.

c. Look for restrictions in the air cleaner.

d. Defect in the air-to-air aftercooler. Check temperature of inlet and outlet air from air cooler. Remove any external or internal restrictions.

4. Plugged or damaged muffler:

Vehicles equipped with catalytic mufflers, especially those that idle for long periods of time and/or operate in cooler climates, are susceptible to plugging. One indication of a plugged muffler is poor engine response. For testing procedures of mufflers, refer to the Testing And Adjusting Section, Measurement Of Pressure In Exhaust Manifold, of this Service Manual. For information concerning the replacement of the muffler refer to the Disassembly And Assembly Section of this Service Manual.

5. Fuel pressure is low:

Make sure there is fuel in the fuel tank. Look for leaks or bad bends in the fuel line between fuel tank and fuel transfer pump. Look for air in the fuel system. Make sure the fuel filters are clean, then check fuel pressure. The outlet pressure of the fuel transfer pump must be a minimum of 200 kPa (29 psi) at full load speed. If fuel pressure is lower than the above pressure, check the fuel transfer pump and fuel pressure regulating orifice at the fuel return line.

6. Low quality fuel or water in fuel:

Test the engine using fuel according to recommendations by Caterpillar Inc. Refer to Truck Performance And Driveability Diagnostic Guide, LEBT3477. Remove the fuel from the fuel tank. Install new fuel filter. Put a good grade of clean fuel in the fuel tank. Fuel API rating can be easily checked using the 1P7408 Thermo-Hydrometer. Instructions are given in Special Instruction SEHS8874.

7. Defect in unit injector(s):

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for Injector Solenoid Circuit Test.

8. Valve adjustment not correct:

Check and make necessary adjustments as per Testing and Adjusting Section of the Service Manual.

9. Turbocharger has carbon deposits or other cause of friction:

Make inspection and repair turbocharger as necessary.

10. Air, water, or gas in fuel:

a. Check inlet line or transfer pump for air leak.

b. Check sleeve or sleeve to head joint for water leak.

c. Check unit injector seat erosion in sleeve or tip seal for combustion gas leak.

11. Defect in boost sensor:

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for Consistent Low Power/Poor Or No Response To Throttle.

12. Defect In Coolant Temperature Sensor:

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for Engine Sensor Open Or Short Circuit Test.

13. Defect In Throttle Position Sensor:

14. Defect In Injection Actuation Pressure Sensor:

If injection actuation pressure is below desired, then the unit injectors may not be able to inject fuel. The injection Actuation Pressure Control Valve could cause this if debris is clogging the valve. Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for Injection Actuation Pressure Test.

Problem 7: Too Much Vibration

Probable Cause(s):

* Vibration Damper Loose

* Vibration Damper Has A Defect

* Engine Supports Are Loose, Incorrect Or Have A Defect

* Driven Equipment Is Not In Alignment Or Is Out Of Balance

* Misfiring Or Running Rough

1. Vibration damper loose:

Check vibration damper for damage. Tighten bolts. If vibration damper bolt holes have damage or wear, replace with new parts.

2. Vibration damper has a defect:

Install a new vibration damper.

3. Engine supports are loose, incorrect or have a defect:

Tighten all mounting bolts. Install new components if necessary.

4. Driven equipment is not in alignment or is out of balance:

Check alignment and balance, correct if needed.

5. Misfiring or running rough:

Refer to Problem 4: Engine Misfiring Or Running Rough.

Problem 8: Loud Combustion Noise (Sound)

Probable Cause(s):

* Air In Fuel System

* Low Quality Fuel

* Defect In Unit Injector(s)

* Mechanical Problem

* Excessive Injection Actuation Pressure

* Cold Mode Operation

* Engine Timing Incorrect

1. Air in fuel system:

With air in the fuel system the engine will normally be difficult to start, run rough and release a large amount of white smoke. Find the air leak in the fuel system and correct it. If air is in the system, it will generally get in on the suction side of the fuel transfer pump. Refer to Problem 34: Air In Fuel.

2. Low quality fuel:

Check fuel quality. Refer to Truck Performance And Driveability Diagnostic Guide LEBT3477. If fuel is of low quality then remove the fuel from the fuel tank. Install new fuel filter. Put a good grade of clean fuel in the fuel tank.

3. Defect in unit injector(s):

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for Injector Solenoid Circuit Test.

4. Mechanical problem:

Find and correct the problem. The problem may be incorrect valve adjustment, sticking valve, or other internal problem.

5. Excessive injection actuation pressure:

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for Injection Actuation Pressure Test.

6. Cold Mode Operation:

Monitor any of the electronic service tool Status screens to verify the engine has shifted out of Cold Mode. An Active Cold Mode is indicated in the upper corner of any of the Status Screens. Check the engine after it has had a chance to warm up.

7. Engine timing incorrect:

a. Using an electronic tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Diesel Truck Engine Electronic Troubleshooting SENR6566, for Engine Speed/Timing.

b. If the engine has undergone repair involving the cam gear then Refer to Disassembly And Assembly, SENR6553, for the proper procedure for camshaft removal and installation. The cam gear is keyed to the camshaft. If the gear is installed correctly, it is nearly impossible for the timing to be off enough to cause knocking.

Problem 9: Valve Train Noise

Probable Cause(s):

* Too Much Valve Lash

* Damage To Valve Springs, Locks, Push Tube Or Worn Valve Lifter

* Not Enough Lubrication

* Damage To Valves

* Damage To Camshaft

1. Too much valve lash:

Check and make necessary adjustments as per Testing and Adjusting Section of the Service Manual.

2. Damage to valve springs, locks, push tube, or broken or worn valve lifter:

Install new parts where necessary. Broken locks can cause the valve to get into the cylinder. This will cause much damage.

3. Not enough lubrication:

Check lubrication in valve compartment. There must be a strong flow of oil at engine high rpm, but only a small flow of oil at low rpm. Oil passages must be clean, especially those that send oil to the cylinder head.

4. Damage to valves:

Make a replacement of the valves and make an adjustment as necessary.

5. Damage to camshaft:

Make a replacement of parts with damage. Clean engine thoroughly.

Problem 10: Oil In Cooling System

Probable Cause(s):

* Defect In Core Of Engine Oil Cooler

* Failure Of Cylinder Head Gasket

1. Defect in core of engine oil cooler:

Inspect cooler and make a replacement or repair defective oil cooler. Flush cooling system to remove oil.

2. Failure of cylinder head gasket:

Remove the radiator cap and with the engine running look for air bubbles in the coolant. Bubbles in the coolant are a sign of probable leakage at the head gasket. Remove the cylinder head from the engine. Check the cylinder head, cylinder walls and head gasket surface of the cylinder block for cracks. When installing the head, use a new head gasket. Tighten the bolts that hold the cylinder head according to the Specifications Section of the Service Manual.

Problem 11: Mechanical Noise (Knock) In Engine

Probable Cause(s):

* Failure Of Bearings For Connecting Rod

* Damaged Gears

* Damaged Crankshaft

* Defect In Accessory Equipment

1. Failure of bearings for connecting rod:

Inspect the bearings for the connecting rods and the bearing surfaces (journals) on the crankshaft. Install new parts where necessary.

2. Damaged gears:

Install new parts where necessary.

3. Damaged crankshaft:

Make replacement of the crankshaft.

4. Defect in accessory equipment:

Repair as needed or install new components.

Problem 12: Fuel Consumption Too High

Probable Cause(s):

* Air Inlet Restriction

* Exhaust Restriction

* Fuel System Leaks

* Low Quality Fuel

* Defect In Turbocharger

* Fuel And Combustion Noise (Knock)

* Defect In Unit Injector(s)

* Improper Speed/Timing Calibration

* Improper Vehicle Operation

1. Air inlet restriction:

Restriction of the air coming into the engine can cause high cylinder temperatures and more than normal amount of heat to pass to the cooling system. Check for restriction with a water manometer or a vacuum gauge (which measures in inches of water). Connect the gauge to the engine air inlet between the air cleaner and the inlet to the turbocharger. With the gauge installed, run the engine at full load rpm and check the restriction. Maximum restriction of the air inlet is 6.22 kPa (25 inches of water). If the indication is higher than maximum permissible restriction, remove the foreign material from the filter element, or install a new filter element and check for the restriction again. If the indication is still too high, there must be a restriction in the inlet piping.

2. Exhaust restriction:

Restriction in the exhaust system can cause high cylinder temperatures and more than normal amount of heat to pass to the cooling system. To check if there is an exhaust restriction, make a visual inspection of the exhaust system. Check for damage to piping or for a defective muffler. If no damage is found, check the exhaust system for back pressure from the exhaust (pressure difference measurement between exhaust outlet and atmosphere). The back pressure must not be more than 10.0 kPa (40 inches of water). Check the system by removing the exhaust pipes from the exhaust manifolds. With the exhaust pipes removed, start and run the engine to see if the problem is corrected.

3. Fuel system leaks:

a. Check fuel system for any external leaks. Check all lines, hoses, and fittings for leaks and tighten or replace as necessary.

b. Check for a defective O-ring seal on the top of the unit injector. Remove the fuel supply line at the front of the cylinder head and pressurize the cylinder head (the return to fuel tank line will have to be blocked). Look for fuel leaking from the unit injectors where they seal with the cylinder head. If fuel is leaking from the unit injector, remove the unit injector and replace the upper O-ring seal. Also depending on the amount of leakage an oil sample should be taken and checked for fuel dilution. Change oil and oil filter if necessary. While the cylinder head is pressurized, check for porosity around the oil drain back holes. If porosity is found, replace the cylinder head. If fuel is found in the coolant, then check the unit injector sleeves in the cylinder head for cracks or erosion. If defects are found, then remove the sleeves and install new sleeves.

NOTE: Refer to Disassembly And Assembly, SENR6553, for the proper procedure for unit injector removal and installation.

4. Low quality fuel:

Test the engine with fuel according to recommendations by Caterpillar Inc. Refer to Truck Performance And Driveability Diagnostic Guide, LEBT3477.

5. Defect in Turbocharger:

Check to see if turbocharger spins freely. Repair as needed or install new components.

6. Fuel and combustion noise (knock):

See Problem No. 4, Engine Misfiring or Running Rough. See Problem No. 9, Loud Combustion Noise.

7. Defect in unit injector(s):

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Injector Solenoid Circuit Test.

8. Improper speed/timing calibration:

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Engine Speed/Timing Calibration.

9. Improper vehicle operation:

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, Poor Fuel Consumption.

Problem 13: Too Much Valve Lash

Probable Cause(s):

* End Of Stem Worn Or Rocker Arm Contact Surface Worn

* Worn Push Rods

* Broken Or Worn Valve Lifter

* Worn Lobes On Camshaft

* Not Enough Lubrication

1. End of valve stem worn or rocker arm contact surface worn:

If there is too much wear, install new valves or rocker arms. Check and make necessary adjustments as per Testing and Adjusting Section of the Service Manual.

2. Worn push rods:

If there is too much wear, install new valves or rocker arms. Check and make necessary adjustments as per Testing and Adjusting Section of the Service Manual.

3. Broken or worn valve lifter:

Install new valve lifters. Check camshaft for wear. Check for free movement of valves or bent valve stem. Clean engine thoroughly. Check and make necessary adjustments as per Testing and Adjusting Section of the Service Manual.

4. Worn lobes on camshaft:

Check valve lash. Check for free movement of valves or bent valve stems. Install a new camshaft. Install new valve lifters. Check and make necessary adjustments as per Testing and Adjusting Section of the Service Manual.

5. Not enough lubrication:

Check lubrication in valve compartment. There must be a strong flow of oil at high engine rpm, but only a small flow at low rpm. Oil passages must be clean, especially those sending oil to the cylinder head.

Problem 14: Little Or No Valve Lash

Probable Cause(s):

* Worn Valve Seat Or Face Of Valve

1. Worn valve seat or face of valve:

Reconditioning of cylinder head is needed. Check and make necessary adjustments as per Testing and Adjusting Section of the Service Manual.

Problem 15: Oil At The Exhaust

Probable Cause(s):

* Failed Turbocharger Seals

* Worn Or Failed Valve Guide Seals

* Worn Valve Guides

* Broken Or Worn Piston Rings

* Scored Or Worn Cylinder Wall(s)

1. Failed turbocharger seals:

Check inlet manifold and exhaust manifold for oil. If oil is present, replace the turbocharger.

2. Worn or failed valve guide seals:

Inspect seals and replace as necessary.

3. Worn valve guides:

See the Specifications Section of the Service Manual for the maximum permissible wear of the valve guides. If necessary, recondition the cylinder head.

4. Broken or worn piston rings:

Pistons or rings that have damage can be the cause of too much pressure in the crankcase. This condition will cause more than the normal amount of fumes (blow-by) coming from the crankcase breather. The 8T2700 Indicator Group is used to check the amount of blow-by. The test procedure is in Special Instruction, SEHS8712. Inspect and install new parts as needed.

5. Scored or worn cylinder walls:

Inspect cylinder walls for problems. Hone, or bore and sleeve as necessary.

Problem 16: Engine Has Excessive Early Wear

Probable Cause(s):

* Dirt In Lubrication Oil

* Contaminated Oil

* Dirt In The Inlet Air

* Fuel Leakage Into Lubrication Oil

* Incorrect Lubrication Oil

* Incorrect Engine Settings

* Incorrect Maintenance Interval For The Desired Application

1. Dirt in lubrication oil:

Remove dirty lubrication oil. Install new filters. Put clean oil in the engine. Check oil filter bypass valve for a weak or broken spring. Cut open filter (s) to check for signs of component failure.

2. Contamination oil:

Take a SOS sample of engine oil for analysis.

3. Dirt in the inlet air:

Inspect all gaskets and connections. Make repairs if leaks are found.

4. Fuel leakage into lubrication oil:

This will cause high fuel consumption and low engine oil pressure. This condition may also increase the oil level in the crankcase. Make repairs if leaks are found. Install new parts where needed. Replace oil and filter (s).

5. Incorrect lubrication oil:

Check oil recommendations for proper oil specifications for engine operating conditions.

6. Incorrect engine settings:

Check valve settings. Refer to the Testing And Adjusting Section of the Service Manual.

7: Incorrect maintenance interval for the desired application:

Review oil change intervals in relation to the nature and severity of the engine application. Review shop records to verify that the recommended intervals are being followed.

Problem 17: Coolant In Lubrication Oil

Probable Cause(s):

* Failure Of The Oil Cooler Core

* Failure Of Cylinder Head Gasket

* Failure Of Seal Between Cylinder Head And Sleeve In Unit Injector Bore

* Crack Or Defect In Cylinder Head

* Crack Or Defect In Cylinder Block

1. Failure of the oil cooler core:

Install a new core for the defective oil cooler. Drain crankcase and refill with clean lubricant. Install new oil filter.

2. Failure of cylinder head gasket:

Remove the radiator cap then start the engine. Look for air bubbles in the coolant. Bubbles in the coolant are a sign of probable leakage at the head gasket. Remove the cylinder head from the engine. Check the cylinder head, cylinder walls and head gasket surface of the cylinder block for cracks. When installing the head, use a new head gasket. Tighten the bolts that hold the cylinder head according to the Specifications Section of the Service Manual.

3. Failure of seal between cylinder head and sleeve in unit injector bore:

Replace sleeve. Apply sealant per instruction in the Specifications Section of the Service Manual.

4. Crack or defect in cylinder head:

Install a new cylinder head.

5. Crack or defect in cylinder block:

Install a new cylinder block.

Problem 18: Too Much Exhaust Smoke (Black Or Gray):

Engine Runs Smoothly (Go to Step 1)

Probable Cause(s):

* Not Enough Air For Combustion

* Exhaust System Restriction

* Low Quality Fuel

* Valve Adjustment Is Not Correct Or Valve Leakage

* Defective Unit Injector

* Low Injection Actuation Pressure

* Defect In Boost Sensor

Engine Runs Rough (Go to Step 9)

* Misfiring Cylinders

* Air In Fuel System

1. Not enough air for combustion:

A. Restriction in air cleaner:

If the air cleaner has a restriction indicator, see if the red piston is in view. If there is no restriction indicator, restriction can be checked with a water manometer or a vacuum gauge (which measures in inches of water). Make a connection of the piping between the air cleaner and the air inlet of the turbocharger. Check with the engine running at full load rpm. Maximum restriction is 6.22 kPa (25 inches of water). If a guage is not available, visually check the air cleaner element for dirt. If the element is dirty, clean the element or install a new element.

B. Air inlet piping damage or restriction:

Make a visual inspection of the air inlet system and check for damage to piping, rags in the inlet piping, or damage to the rain cap or the cap is pushed too far onto the inlet pipe. If no damage is seen, check the inlet restriction with a clean air cleaner element.

C. Turbocharger not operating properly:

Check turbocharger for proper operation.

2. Exhaust system restriction:

Make a visual inspection of the air inlet system and check for damage to piping or a defective muffler. If no damage is found, check the system by checking the back pressure from the exhaust (pressure difference measurement between exhaust outlet and atmosphere). The back pressure must not be more than 10.0 kPa (40 inches of water). If a guage is not available, check by removing the exhaust pipes from the exhaust manifold. With the exhaust pipes removed, start the engine and load the engine on a dynamometer to see if the problem is corrected.

3. Low quality fuel:

Test the engine with fuel according to recommendations by Caterpillar Inc.

4. Valve adjustment is not correct or valve leakage:

Check and make necessary adjustments as per Testing and Adjusting Section of the Service Manual.

5. Defective unit injectors:

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Injector Solenoid Circuit Test.

6. Low injection actuation pressure:

If the injection actuation pressure is less than desired, then the unit injectors may not be able to inject fuel. The injection Actuation Pressure Control Valve could cause this if debris is clogging the valve. Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for Injection Actuation Pressure Test.

7. Defect in boost sensor:

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for Excessive Black Smoke.

Engine Runs Rough

Probable Cause(s):

9. Misfiring cylinders:

Refer to Problem 4: Engine Misfiring Or Running Rough.

10. Air in fuel system:

Problem 19: Too Much Exhaust Smoke At Normal Operating Temperatures (White/Black Or Blue Smoke)

A. White Smoke (Go to Step 1)

Probable Cause(s):

* Cold Outside Temperature

* Long Idle Periods

* Low Quality Fuel

* Air In Fuel System

* Water In Fuel System

* Fuel Pressure Is Low

* Air Inlet Heater (if equipped) Not Operating Properly

* Valve Adjustment Not Correct

* Misfiring Cylinder(s)

* Intake/Exhaust Valves Or Piston Rings Leak Compression

* Defective Unit Injector(s)

* Defect In Intake Manifold Air Temperature Sensor

* Defect In Coolant Temperature Sensor

B. Black Smoke (Go to Step 17)

Probable Cause(s):

* Defective Unit Injector(s)

* Restrictions And/Or Leaks In Air Inlet System

* Exhaust System Restriction

* Defective Turbocharger

C. Blue Smoke (Go to Step 21)

Probable Cause(s):

* Oil Level In Engine Too High

* Failure Of Turbocharger Oil Seal

* Worn Or Broken Valve Guides

* Worn Piston Rings And/Or Cylinder Wall(s)

* Wear Or Damage To Pistons

1. Cold outside temperatures:

When the air outside is cold, the cylinder temperature is cooler. Not all the fuel will burn in the cylinders. The fuel which does not burn comes out the exhaust as white smoke. White smoke is normal in cold temperatures until the engine operates long enough to become warm. There will be less white smoke if No. 1 diesel fuel is used.

The inlet air heater is used to improve the cold start capability of the engine and to reduce white smoke after startup. The ECM controls the inlet air heater grid and indicator lamp (on truck dash) through the inlet air heater relay. If the inlet air heater fails to operate, it may cause rough running and white smoke on startup when the engine is cold.

2. Long idle periods:

When an engine runs at idle speed for a long period of time, the cylinders cool and all of the fuel does not burn. Do not idle an engine for a long period of time. Stop an engine when it is not in use. If long idle periods are necessary, use No. 1 diesel fuel.

3. Low quality fuel:

Test the engine using fuel according to recommendations by Caterpillar Inc. Refer to Truck Performance And Driveability Diagnostic Guide, LEBT3477.

4. Air in fuel system:

5. Water in fuel system:

Water in the fuel system can result in misfiring. Check injection sleeve or head gasket for water leak.

6. Fuel pressure is low:

Make sure there is fuel in the fuel tank. Look for leaks or bad bends in the fuel line between fuel tank and fuel transfer pump. Look for air in the fuel system. (If fuel in the fuel tank cannot be checked for air, install a sight tube in the fuel line). Make sure the fuel filters are clean, then check fuel pressure. The outlet pressure of the fuel transfer pump must be 400 to 525 kPa (58 to 76 psi) at full load speed measured at the inlet to the secondary filter. If fuel pressure is lower than the above pressure, check the fuel transfer pump and fuel pressure regulating orifice at the fuel return line.

7. Air Inlet Heater (if equipped) Not Operating Properly:

Refer to Problem 32: Air Inlet Heater (If Equipped) in the Troubleshooting Section of the Service Manual.

8. Valve adjustment not correct:

Check and make necessary adjustments as per Testing and Adjusting Section of the Service Manual.

9. Misfiring cylinder(s):

Refer to Problem 4: Engine Misfiring Or Running Rough.

10. Intake/exhaust valves or piston rings leak compression:

a. Check intake/exhaust valves for low compression. Repair or replace as necessary.

b. Worn piston rings and/or cylinder walls can be the cause a loss of compression. This condition can cause more than the normal amount of fumes (blow-by) coming from the crankcase breather. The 8T2700 Indicator Group is used to check the amount of blow-by. The test procedure is in Special Instruction, SEHS8712. If necessary make a visual inspection of the cylinder walls and piston rings. Measure the cylinder walls and piston rings. For the cylinder and piston ring specifications see the Specification Section of the Service Manual. Repair and replace parts as necessary.

11. Defective unit injector(s):

Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Injector Solenoid Test.

12. Defect in intake manifold air temperature sensor:

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Engine Sensor Open or Short Circuit Test.

13. Defect in coolant temperature sensor:

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Engine Sensor Open or Short Circuit Test.

Black Smoke

Probable Cause(s):

14. Defective unit injector(s):

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Injector Solenoid Test.

15. Restrictions and/or leaks in air inlet system:

a. Check for leaks.

b. Check the pressure in the air inlet manifold. Check pressure in the air inlet manifold. Look for restrictions at the air cleaner. Check the ATAAC for cracks.

c. Look for restrictions in the air cleaner.

d. Defect in the air-to-air aftercooler. Check temperature of inlet and outlet air from air cooler. Remove any external or internal restrictions.

16. Exhaust System Restriction:

Make a visual inspection of the air inlet system and check for damage to piping or a defective muffler. If no damage is found, check the system by checking the back pressure from the exhaust (pressure difference measurement between exhaust outlet and atmosphere). The back pressure must not be more than 1016 mm (40 in) of water. If a gauge is not available, check by removing the exhaust pipes from the exhaust manifold. With the exhaust pipes removed, start the engine and load the engine on a dynamometer to see if the problem is corrected.

17. Defective Turbocharger:

Check inlet manifold for oil and repair turbocharger.

Blue Smoke

Probable Cause(s):

18. Oil level in engine too high:

Do not put too much oil in the crankcase. If the oil level in the crankcase goes up as the engine is used, check for fuel in the lubrication oil. Refer to Problem 29: Fuel In Lubrication Oil.

19. Failure of turbocharger oil seal:

Check inlet manifold for oil and repair turbocharger.

20. Worn or broken valve guides:

See the Specifications Section of the Service Manual for the maximum permissible wear of the valve guides. If necessary, recondition the cylinder head.

21. Worn piston rings and/or cylinder walls:

Worn piston rings and/or cylinder walls can be the cause of blue smoke and can cause a loss of compression. This condition can cause more than the normal amount of fumes (blow-by) coming from the crankcase breather. The 8T2700 Indicator Group is used to check the amount of blow-by. The test procedure is in Special Instruction, SEHS8712. If necessary make a visual inspection of the cylinder walls and piston rings. Measure the cylinder walls and piston rings. For the cylinder and piston ring specifications see the Specification Section of the Service Manual. Repair and replace parts as necessary.

NOTE: High wear at low hours is normally caused by dirt coming into the engine with the inlet air.

22. Wear or damage to pistons:

Check piston ring to groove clearance. Pistons which have worn grooves and pistons with damage or defects can cause blue smoke and too much oil consumption. Make sure the oil return holes under the oil ring are open. Replace pistons as necessary.

Problem 20: Engine Has Low Oil Pressure

Probable Cause(s):

* Insufficient Oil

* Defect In Oil Pressure Gauge Or Sending Unit

* Dirty Oil Filter Or Oil Cooler

* Diesel Fuel In Lubrication Oil

* Oil Pump Has A Defect

* Oil Pump Suction Pipe Has A Defect

* Oil Pressure Relief Valves Do Not Close

* O-ring Defective

* Too Much Clearance Between Rocker Arm Shaft And Rocker Arms

* Too Much Clearance Between Camshaft And Camshaft Bearings

* Too Much Clearance Between Crankshaft And Crankshaft Bearings

1. Insufficient oil:

Check oil dipstick for correct level.

2. Defect in oil pressure gauge or sending unit:

Install new gauge or sending unit.

3. Dirty oil filter or oil cooler:

Change oil and oil filter. If problem persists, check the operation of bypass valve for the filter. Clean or install new oil cooler core. Verify that maintenance is done at correct intervals.

4. Diesel fuel in lubrication oil:

Find the place where diesel fuel gets into the lubrication oil. Pressure check the fuel system to check for porosity in the cylinder head or a leaking O-ring seal on an unit injector. Make repairs as needed. Remove the lubrication oil that has diesel fuel in it. Install new oil filter. Fill the engine with clean oil. Refer to Problem 29: Fuel In Lubrication Oil.

5. Oil pump has a defect:

Repair or replace oil pump.

6. Oil pump suction pipe has a defect:

Replacement of pipe is needed.

7. Oil pressure relief valve does not close:

Clean valve and housing. Install new parts as necessary. Check bypass valves in oil cooler and oil filter base.

8. O-ring defective.

Check O-ring in the oil line from the oil pump to the engine.

9. Too much clearance between rocker arm shaft and rocker arms:

Check lubrication in valve compartments. Install new parts as necessary.

10. Too much clearance between camshaft and camshaft bearings:

Install new camshaft and camshaft bearings if necessary.

11. Too much clearance between crankshaft and crankshaft bearings:

Inspect the bearings and make replacement as necessary.

Problem 21: Engine Uses Too Much Lubrication Oil

Probable Cause(s):

* Too Much Lubrication Oil In The Engine

* Oil Leaks

* Oil Temperature Is Too High

* Worn Valve Guide Seals

* Worn Pistons, Rings Or Cylinder Walls

* Failure Of Seal Rings In Turbocharger

* Worn Valve Guides

1. Too much lubrication oil in the engine:

Remove extra oil. Find where extra oil comes from. Put correct amount of oil in engine.

2. Oil leaks:

Find all oil leaks. Make repairs as needed. Check for a dirty crankcase breather.

NOTE: Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engines Electronic Troubleshooting, SENR6566 for electronic or hydraulic problems.

3. Oil temperature is too high:

Check operation of oil cooler. Install new parts if necessary. Clean the core of the oil cooler. Check coolant temperature. High oil temperature is a function of engine overheating.

4. Worn valve guide seals:

Replace as necessary.

5. Worn pistons, rings or cylinder walls:

16. Failure of seal rings in turbocharger:

Check inlet piping, ATAAC and manifold for oil and make repairs to the turbocharger if necessary.

7. Worn valve guides:

See the Specifications Section of the Service Manual for the maximum permissible wear of the valve guides. If necessary, recondition the cylinder head.

Problem 22: Above Normal Coolant Temperature

NOTE: The 3100 HEUI Electronic Control System will activate fault codes to warn of engine overheating. Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, Event Codes Test.

Probable Cause(s):

* Low Coolant Level

* Incorrect Mixture

* Air In Cooling System

* Fan Clutch

* Temperature Gauge

* Sending Unit

* Radiator

* Radiator Cap

* Incorrect Fan, Fan Or Shroud Not In Correct Position

* Loose Belt(s)

* Hose(s)

* Air Inlet Restriction

* Exhaust Restriction

* Shunt Line

* Water Temperature Regulator

* Defective Water Pump

* Air Flow Through Engine Compartment

* Aftercooler

* Outside Temperature

* Operate At High Altitude

* Engine Used In Lug Condition

1. Low coolant level:

If the coolant level is too low, not enough coolant will go through the engine and radiator. This lack of coolant will not take enough heat from the engine and there will not be enough flow of coolant to release the heat into the cooling air. Low coolant level is caused by leaks or incorrect filling of the radiator. With the engine cool, be sure that coolant can be seen at the low end of the fill neck on the radiator top tank.

2. Incorrect mixture:

Check the mixture of antifreeze and water. The mixture should be approximately 50 percent water and 50 percent antifreeze with a 3 to 6 percent coolant conditioner. If the system is not correct, drain the system as needed and put the correct mixture of water, antifreeze and coolant conditioner in the cooling system.

3. Air in cooling system:

Air can enter the cooling system in different ways. The most common causes are not filling the cooling system correctly, and combustion gas leaking into the cooling system. Combustion gas can get into the system through inside cracks, a defective cylinder head, leaking unit injector sleeve, or head gasket. Air in the cooling system causes a reduction in coolant flow and bubbles in the coolant. Air bubbles hold coolant away from the engine parts, preventing the transfer of heat to the coolant.

4. Fan clutch:

A fan clutch not turning at the correct speed can cause improper air speed across the radiator core. The lack of proper air flow across the core can cause the coolant not to cool to the proper temperature differential.

5. Temperature gauge:

A temperature gauge which does not work correctly will not show the correct temperature. If the temperature gauge shows that the coolant temperature is too hot but other conditions are normal, either install a gauge of known accuracy, or check the cooling system with the 8T0470 Thermistor Thermometer Group. Compare temperature gauge with coolant temperature on the display status screen of the electronic service tool.

6. Sending unit:

In some conditions the temperature sensor in the engine sends signals to a sending unit which converts these signals to an electrical impulse which is used by a mounted gauge. If for some reason the sending unit malfunctions or the electric wire breaks or shorts out the gauge can show an incorrect reading.

7. Radiator:

a. Restriction to flow of coolant through core tubes of radiator of air flow restriction. Check for debris between the fins of the radiator core which prevents free air flow through the radiator core. Check the radiator for debris, dirt, or deposits on the inside of the radiator core which will prevent free flow of coolant through the radiator.

b. A radiator which is too small does not have enough area to release the heat to the cooling air. This will cause the engine to run at a higher than normal temperature. Make sure the radiator size is according to the OEMs specifications.

8. Radiator cap:

A pressure drop in the radiator can cause the boiling point to lower causing the cooling system to boil over. A cooling system pressure tester may be used to check the cooling system pressure as well as the pressure cap relief valve. If the cap fails the test, check the rubber seal on the cap as well as the operation of the pressure relief valve.

9. Incorrect fan, fan or shroud not in correct position:

A incorrect fan, or a fan or shroud in a wrong position will cause a reduction or a loss of air flow through the radiator. The fan must be large enough to send air through most of the area of the radiator core.

10. Loose belt(s):

Loose fan or water pump belts will cause a reduction in air and coolant flow. Tighten the belts according to the Belt Tension Charts.

11. Hose(s):

Defective hoses with leaks can normally be seen. Hoses that have no visual leaks can collapse (pull together) during operation and cause a restriction in the flow of coolant. Hoses become soft and/or get cracks after a period of time. Hoses must be changed after 3000 hours or two years of use. The inside of a hose can deteriorate, and the loose particles of the hose can cause a restriction of the coolant flow.

12. Air inlet restriction:

13. Exhaust restriction:

14. Shunt line:

A restriction of the shunt line from the radiator top tank to the engine water pump inlet, or a shunt line not installed correctly, will cause a reduction in water pump efficiency. The result will be low coolant flow and overheating.

15. Water temperature regulator:

A water temperature regulator that does not open, or only opens part of the way, can cause above normal heating. To test the water temperature regulator, see the Testing and Adjusting Section of the Service Manual.

16. Defective water pump:

A water pump with a loose or damaged impeller does not pump enough coolant for correct engine cooling. Remove the water pump and check for damage to the impeller. If the impeller has no damage, check the impeller clearance.

17. Air flow through engine compartment:

The air flow through the radiator comes out of the engine compartment. Make sure the filters, air conditioners and similar items are not installed in a way which prevents free flow of air into and out of the engine compartment.

18. Aftercooler:

Restriction of air flow through the air-to-air aftercooler (if equipped). Check for debris or deposits which would prevent the free flow of air through the aftercooler.

19. Outside temperature:

When outside temperatures are too high for the rating of the cooling system, there is not enough temperature difference between the outside air and coolant temperatures.

20. Operation at high altitude:

The cooling capacity of the cooling system goes down as the engine is operated at higher altitudes. A system, under pressure, large enough to keep the coolant from boiling must be used.

21. Engine used in a lug condition:

"Lugging" Lugging can occur when there is too much load applied to the engine or the engine is run at a lower rpm. This low rpm causes a reduction in air flow through the radiator, and a reduction in the flow of coolant through the system. This combination of less air and less coolant flow during high input of fuel will cause above normal heating.

Problem 23: Below Normal Coolant Temperature

NOTE: For operation in cold or very cold temperatures, a winterfront cover or radiator shutters are recommended.

Probable Cause(s):

* Long Idle Periods

* Very Light Loads

* Water Temperature Regulator

* Air Vent Valve

* Fan Clutch Engaged

1. Long idle periods:

When the engine is running with no load, only a small quantity of fuel is burnt and engine heat is removed too fast.

2. Very light load:

Very light loads can cause below normal heating because of the low heat input of the engine. A slight restriction of air flow through the radiator will help to correct this problem.

3. Water temperature regulator:

A water temperature regulator that is "stuck" open (will not move to the closed position) will cause below normal heating. A regulator that is stuck between the open and closed positions, or a vent valve that is stuck open, can cause below normal coolant temperatures when the engine has a light load.

4. Air vent valve:

An air vent valve located in the water temperature regulator that is stuck open, can cause below normal coolant temperatures when the engine has a light load. If fan clutch remains engaged when it should release, overcooling may occur.

5. Fan clutch engaged:

a. Check coolant temperature sensor. Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Engine Sensor Open or Short Circuit Test.

b. Check exhaust brake circuit. Make repairs as necessary.

Problem 24: Exhaust Temperature Too High

Probable Cause(s):

* Air Inlet System Has A Leak

* Exhaust System Has A Leak

* Air Inlet Or Exhaust System Has A Restriction

* Engine Operated In A Lug Condition

* Operating Above Altitude Limits

* Defective Turbocharger

1. Air inlet system has a peak:

Check pressure in the air inlet manifold, or read boost pressure (Boost Pr) on Display Status Screen of electronic service tool. If boost pressure is below normal for a given operating condition, look for loose tubing or piping in the air inlet system or a leak in the ATAAC core. Correct any leaks.

2. Exhaust system has a leak:

Find cause of exhaust leak. Make repairs as necessary.

3. Air inlet or exhaust system has a restriction:

Check air cleaner and inlet piping for restrictions. Remove restriction.

4. Engine operated under heavy load below peak torque rpm:

The engine should be operated between rated and peak torque rpms. If operated for an extended period under heavy load below peak torque rpm, the low coolant rate of flow and low air flow through the radiator may cause overheating. Train drivers in correct engine operation.

5. Operating above altitude limits:

Consult with Fuel Setting And Related Information Fiche specifications for proper operating altitude for engine certifications.

7. Defective Turbocharger:

If turbocharger is equipped with a wastegate, and the wastegate is not operating as it should, excessive boost pressure may be generated resulting in high internal cylinder pressures and high exhaust temperatures. Verify correct wastegate operation, preferably on a dynamometer. If incorrect, replace turbine housing, tubing or turbocharger as needed. There is no field adjustment on wastegate settings.

Problem 25: Starting Motor Does Not Turn

Probable Cause(s):

* Battery Has Low Output

* Wires Or Switch Has Defect

* Starting Motor Solenoid Has A Defect

* Starting Motor Has A Defect

1. Battery has low output:

Check condition of battery. Charge battery or make replacement as necessary.

2. Wires or switch has defect:

Make repairs or replacement as necessary.

3. Starting motor solenoid has a defect:

Install a new solenoid.

4. Starting motor has a defect:

Make repair or replacement of starting motor.

Problem 26: No Charging Current, Or Low Or Irregular Charging Current

Probable Cause(s):

* Loose Drive Belt For Alternator

* Charging Or Ground Return Circuit Or Battery Connections Have A Defect

* Alternator Regulator Has A Defect

* Alternator Brushes Have A Defect

* Rectifier Diodes Have A Defect

* Rotor (Field Coil) Has A Defect

1. Loosen drive belt for alternator:

Make an adjustment to put the correct tension on the drive belt.

2. Charging or ground return circuit or battery connections have a defect:

Inspect all cables and connections. Clean and tighten all connections. Make replacement of defective parts.

3. Alternator regulator has a defect:

Replace the alternator regulator.

4. Alternator brushes have a defect:

Install new brushes.

5. Rectifier diodes have a defect:

Make replacement of rectifier diode that has a defect.

6. Rotor (field coil) has a defect:

Install a new rotor.

Problem 27: Alternator Charge Too High

Probable Cause(s):

* Alternator Or Alternator Regulator Has Loose Connections

* Alternator Regulator Has A Defect

* Alternator Field Lead Shorted To Battery Voltage

1. Alternator or alternator regulator has loose connections:

Tighten all connections to alternator or alternator regulator.

2. Alternator regulator has a defect:

Replace the alternator regulator.

3. Alternator Field Lead Shorted To Battery Voltage

If the alternator field lead becomes shorted to battery voltage, the alternator will charge at maximum rate. When the battery becomes overcharged, voltage and current may rise to levels that result in damage to the battery, alternator and voltage regulator, and also any electrical equipment that is turned on. The ECM is protected up to 32 volts DC; voltages above that may damage the ECM.

Find and correct the short between alternator field circuit and battery voltage. Repair or replace any electrical equipment suffering subsequent damage.

Problem 28: Alternator Has Noise

Probable Cause(s):

* Drive Belt For Alternator Is Worn Or Has A Defect

* Loose Alternator Drive Pulley

* Drive Belt And Drive Pulley For Alternator Are Not In Alignment

* Worn Alternator Bearings

1. Drive belt for alternator is worn or has a defect:

Install a new drive belt for the alternator.

2. Loosen alternator drive pulley:

Check key groove in pulley for wear. If groove is worn, install a new pulley. Tighten pulley nut according to the Specifications Section of the Service Manual.

3. Drive belt and drive pulley for alternator are not in alignment:

Make an adjustment to put drive belt and drive pulley in correct alignment.

4. Worn alternator bearings:

Install new bearings in the alternator, or replace alternator.

Problem 29: Fuel In Lubrication Oil

Probable Cause(s):

* Defective Upper Seal On Unit Injector

* Porosity In Cylinder Head

* Porosity In Fuel Filter Base

* Defective Seal In The Fuel Transfer Pump

1. Defective upper seal on unit injector:

Check for a defective O-ring seal on the top of the unit injector. Remove the fuel supply line at the front of the cylinder head and pressurize the cylinder head (the return to fuel tank line will have to be blocked). Look for fuel leaking from the unit injectors where they seal with the cylinder head. If fuel is leaking from an unit injector, remove the unit injector and replace the upper O-ring seal. Also depending on the amount of leakage an oil sample should be taken and checked for fuel dilution. Change oil and oil filter if necessary.

NOTE: Refer to Disassembly And Assembly, SENR6553, for the proper procedure for unit injector removal and installation.

2. Porosity in the cylinder head:

Pressurize the fuel gallery and check for porosity around the oil drain back holes. If porosity is found, replace the cylinder head.

3. Porosity in fuel filter base:

Check the fuel filter base for porosity or defects. Fuel can be transferred to the crankcase through a defective fuel filter base.

4. Defective seal in the fuel transfer pump:

Check for a defective O-ring seal between the fuel transfer pump and the hydraulic pump. Refer to Disassembly & Assembly, in this service manual.

Problem 30: Fuel In Coolant

Probable Cause:

* Defect In Unit Injector Sleeve

1. Defect in unit injector sleeve:

Remove unit injectors and inspect sleeves in cylinder head unit injector bores. Look for signs of cavitation erosion or cracks. Cavitation on the inside may be due to air bubbles in the fuel. Air bubbles may be due to a leak on the suction side of the fuel transfer pump, or they may be caused by combustion leakage. Check for pathways or cracks at the unit injector/sleeve interference fit near the unit injector nozzle. If cavitation erosion is found on the outside of the sleeve after removal of the sleeve from the cylinder head, it may be due to an incorrect level of coolant conditioner. If any problems are seen, remove the sleeve(s) and replace with new parts.

NOTE: Refer to Disassembly And Assembly, SENR6553, for the proper procedure for unit injector removal and installation.

Problem 31: Loss Of Coolant

A. Outside Leaks (Go to Step 1)

Probable Cause(s):

* Leaks In Hoses Or Connections

* Leaks In The Radiator And/Or Expansion Tank

* Leaks In The Heater

* Leaks In The Water Pump

* Cylinder Head Gasket Leakage

B. Coolant Leaks At The Overflow Tube (Go to Step 6)

Probable Cause(s):

* Defective Pressure Cap

* Engine Runs Too Hot

* Expansion Tank Too Small

* Cylinder Head Gasket Leakage Or Crack(s) In Cylinder Head Or Cylinder Block

C. Internal Leakage (Go to Step 10)

Probable Cause(s):

* Erosion Or Crack(s) In Unit Injector Sleeves

* Cylinder Head Gasket Leakage

* Crack(s) In Cylinder Head

* Crack(s) In Cylinder Block

A. Outside Leaks

Probable Cause(s):

1. Leaks in hoses or connections:

Check all hoses and connections for visual signs of leakage. If no leaks are seen, look for damage to hoses or loose clamps.

2. Leaks in the radiator and/or expansion tank:

Put pressure to the radiator and/or expansion tank with the 9S8140 Cooling System Pressurizing Pump Group and check for leaks.

3. Leaks in the heater:

Put pressure to the cooling system with the 9S8140 Cooling System pressurizing Pump Group and check for leaks.

4. Leaks in the water pump:

Check the water pump for leaks before starting the engine, then start the engine and look for leaks. If there are leaks at the water pump, repair or install a new water pump.

5. Cylinder head gasket leakage:

Look for leaks along the surface of the cylinder head gasket. If you see leaks, install a new head gasket. Tighten the bolts that hold the cylinder head according to the Specifications Section of the Service Manual.

B. Coolant Leaks At The Overflow Tube

Probable Cause(s):

6. Defective pressure cap:

Check the sealing surfaces of the pressure cap and the radiator to be sure the cap is sealing correctly. Check the opening pressure and sealing ability of the pressure cap valve with the 9S8140 Cooling System Pressurizing Pump Group.

7. Engine runs too hot:

If coolant temperature is too high, pressure will be high enough to move the cap off of the sealing surface in the radiator and cause coolant loss through the overflow tube. See Problem No. 23, Above Normal Coolant Temperature.

8. Expansion tank too small:

The expansion tank can be either a part of the radiator or it can be installed separately from the radiator. The expansion tank must be large enough to hold the expansion of the coolant as it gets warm or has sudden changes in pressure. Make sure the expansion tank is installed correctly, and the size is according to the recommendations of the OEM.

9. Cylinder head gasket leakage, or crack(s) in cylinder head or cylinder block:

C. Internal Leakage

Probable Cause(s):

10. Erosion or crack(s) in unit injector sleeves:

If fuel is detected in the coolant, a possible cause is a defective unit injector sleeve. Remove the unit injectors and inspect the sleeves for cavitation erosion or cracks. Replace any defective sleeves.

NOTE: Refer to Disassembly And Assembly, SENR6553, for the proper procedure for unit injector removal and installation.

11. Cylinder head gasket leakage:

If the cylinder head gasket leaks between a water passage and an opening into the crankcase, coolant will get into the crankcase.

12. Crack(s) in cylinder head:

Crack(s) in the upper surface of the cylinder head, or an area between a water passage and an opening into the crankcase, can allow coolant to get into the crankcase.

13. Crack(s) in cylinder block:

Crack(s) in the cylinder block between a water passage and the crankcase will let coolant get into the crankcase.

Problem 32: Air Inlet Heater (If Equipped)

If there is a problem with the air inlet heater then refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting Guide, SENR6566.

Problem 33: Soot In The Inlet Manifold

Probable Cause:

* Engine Design

* Defective Valve Or Seat

1. Engine design:

On diesel engines a small amount of soot is normal. This is due to the design characteristics of the engine. Valve overlap allows the intake to open slightly before the exhaust stroke has been completed, which will allow some soot to be pushed into the inlet manifold.

2. Defective valve or seat:

A defective valve or seat allows a large quantity of soot to be pushed into the inlet manifold.

Problem 34: Air In Fuel

Probable Cause:

Install a 4P8278 sight glass in the fuel return line and operate the engine to check for gas bubbles, an indication of air in the fuel system. With air in the fuel system the engine will normally be difficult to start, run rough and release a large amount of white smoke. If air is in the system, it will generally get in on the suction side of the fuel transfer pump. Check for leakage at the connections between the fuel tank and the fuel transfer pump. If leaks are found, tighten the connections or replace the lines.

NOTE: The fuel priming pump (if equipped) may be used to remove the air from the fuel filter and fuel gallery (in the cylinder head), and fill the fuel system with fuel from the fuel tank before the engine is started.

If there are no visual leaks, remove the fuel supply line from the tank and connect it to an outside fuel supply. If this corrects the problem, the suction line (standpipe) inside the fuel tank has a leak.

If this does not correct the problem, check for combustion gas leakage at the base of the fuel injectors. Remove each injector and examine the base of the sleeve and the injector for evidence of nicks or carbon tracking. A magnifying glass and flashlight or shoplight may be needed. The lower sealing surfaces of the nozzle and sleeve should be smooth and without defect. If any defects are noted, the sleeve can be reamed to restore the surface. Refer to Special Instruction "Using the 122-7093 Sleeve Replacement Tool Group", SEHS9120. Check the injector tip seal (O-ring) and upper seal (O-ring) and replace if found defective.

NOTE: Refer to Disassembly And Assembly, SENR6553, for the proper procedure for unit injector removal and installation.

The temperature of an exhaust manifold port can be an indication of a cylinder that has air being delivered to it. Check the exhaust manifold temperatures and compare the results. A lower than normal cylinder temperature indicates that the cylinder may be receiving air from the unit injector.

The color of the exhaust smoke can also indicate which cylinder has a combustion leak. The cylinder that has air will produce smoke that is gray or white in color.

Problem 35: Hydraulic Troubleshooting

For problems with the unit injector, jumper-tube, fuel pump, etc., Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting Guide, SENR6566

Electronic Control System

Diagnostic Codes

Diagnostic codes and their descriptions are given in the Systems Operation under 3100 HEUI Diesel Truck Engines Electronic Connectors And Functions. For an explanation of each diagnostic code see 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566.

ACTIVE Diagnostic Codes

Diagnostic codes are used by the 3100 HEUI Diesel Truck Engines System to warn the vehicle operator of a problem and indicate to the service technician the nature of the problem. Some codes are used only to record an event and do not indicate problems that need repair.

An ACTIVE diagnostic code represents a problem that should be investigated and corrected AS SOON AS POSSIBLE. Repairing the cause of an ACTIVE code will cause the code to be cleared.

When an ACTIVE code is generated, the diagnostic lamp will turn ON and remain ON, blinking every five seconds. If the condition generating the fault occurs only for a brief moment, the lamp will go OFF after five seconds and the code will be LOGGED.

LOGGED Diagnostic Codes And Events

When the ECM generates a diagnostic code, the code will be active and may be logged in permanent memory within the ECM. The ECM has an internal diagnostic clock and will record the hour EACH time a code is logged. Knowing when and how often the code was generated can be a valuable indicator when troubleshooting intermittent problems. Logged codes can be retrieved or erased using a electronic service tool. They can be a valuable indicator when troubleshooting intermittent problems.

Diagnostic Codes that are logged repeatedly may indicate a problem that needs special investigation. Codes that are logged only a few times and do not result in driver complaints, may not need attention until a scheduled maintenance interval.

Certain fault codes and/or event codes cause the system to make major changes in engine operation or limits, as a result of the code being generated.

NOTE: The most likely cause of an intermittent problem is a faulty connection or damaged wiring. Next likely is a component failure (sensor or switch for example). Least likely is the ECM itself.

3100 HEUI Diesel Truck Engine Electronic Service Tools

The Caterpillar electronic service tools for the electronic control systems are designed to help the service technician analyze and locate diagnostic codes or problems within the system. Their use is required to perform sensor calibrations and to read or change programmable engine parameters. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for a list of service tools and the procedures to use them.

Throttle Position Sensor Adjustment

The Throttle Position Sensor (TPS) is used to provide a throttle signal to the Electronic Control Module (ECM). Sensor output is a constant frequency signal whose pulse width varies with throttle position. This output signal is referred to as either "Duty Cycle" or a "Pulse Width Modulated (PWM)" signal and is expressed as a percentage. When correctly adjusted, the TPS will produce a "Duty Cycle" signal of 10 percent to 22 percent at the low idle throttle position and 75 percent to 90 percent at the maximum throttle position. This signal is translated by the ECM into a "Throttle Position" signal of 3 percent at low idle and 100 percent at maximum throttle.

NOTE: The Remote Mounted Throttle Sensor can be calibrated and can get out of calibration. It is not expected that this sensor will be used for the driver's throttle sensor for these engines. It is possible that this sensor may be used in a PTO application. If calibration is required, refer to PTO Installation And Application Guide, SEHS9857.

Pedal-Mounted Throttle Sensor

The Pedal-Mounted Throttle Sensor is mounted on the back of the OEM supplied pedal. No adjustments are required for the Pedal-Mounted Throttle Sensor. Calibration of the Pedal-Mounted Throttle Sensor is done automatically by the ECM. The correct calibration can be displayed with the electronic service tool. The correct percent throttle is displayed as 3 percent with the throttle completely released, and 100 percent with the throttle completely depressed.

Fuel System

Either too much fuel or not enough fuel for combustion can be the cause of a problem in the fuel system.

Many times work is done on the fuel system when the problem is really with some other part of the engine. The source of the problem is difficult to find, especially when smoke comes from the exhaust. Smoke that comes from the exhaust can be caused by a defective unit injector, but it can also be caused by one or more of the reasons that follow:

* Not enough air for good combustion.

* An overload at high altitude.

* Oil leakage into combustion chamber.

* Not enough compression.

Fuel System Inspection

A problem with the components that send fuel to the engine can cause low fuel pressure. This can decrease engine performance.

Fuel System

Fuel System
(1) Fuel inlet port (to fuel transfer pump). (2) Tube assembly (fuel filter to fuel gallery). (3) Tube assembly. (4) Fitting (fuel return to tank. (5) Tube assembly (fuel transfer pump to fuel filter). (6) Fuel filter. (7) Tube assembly (return to tank).

1. Check the fuel level in the fuel tank. Look at the cap for the fuel tank to make sure the vent is not filled with dirt.

2. Check the fuel lines for fuel leakage. Be sure the fuel supply line does not have a restriction or a bad bend.

3. Install a new secondary fuel filter. Clean screen located in the inlet fitting of the fuel transfer pump.

4. Inspect the orifice in tube assembly (7) to see that there is no restriction for proper operation.

Checking Engine Cylinders Separately

To check engine cylinders separately, refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for Injector Solenoid Circuit Test.

Start Up Procedure

For proper starting procedure, refer to 3100 HEUI Diesel Truck Engine Operation And Maintenance Manual.

Use this procedure when an engine is started for the first time after work is done on the fuel system. Use this procedure when an engine is started for the first time after work is done on the fuel systemUse this procedure when an engine is started for the first time after work is done on the fuel system

1. Disconnect the air inlet system from the turbocharger. Use this procedure when an engine is started for the first time after work is done on the fuel system

2. Have a person in position near the turbocharger air inlet with a piece of steel plate large enough to completely cover the turbocharger air inlet.

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Be careful when plate is put against air inlet opening. Due to excessive suction, the plate can be pulled quickly against air inlet opening. To avoid crushed fingers, do not put fingers between plate and air inlet opening.

3. Start the engine. If the engine starts to run too fast or runs out of control, immediately put the steel plate against the turbocharger air inlet. This will stop the air supply to the engine, and the engine will stop.

Fuel Pressure

NOTE: 5P2720 Self-Sealing Probe Adapter and 5P2718 Pressure Probe may be used with the tools needed, to allow installation of pressure probes in the future.

1U5470 Engine Pressure Group

The 1U5470 Engine Pressure Group can be used to check engine fuel pressures.

This tool group has a gauge to read fuel pressure to the cylinder head. Special Instruction, SEHS8907 is with the tool group and gives information for its use.

Fuel Return Line
(1) Tube assembly (fuel transfer pump to fuel filter). (2) Tube assembly (fuel filter to fuel gallery). (3) Fitting (fuel return to tank). (4) Regulating orifice and check valve. (5) Cylinder head. (6) Fuel gallery. (7) Fuel outlet port.

Fuel pressure at the inlet to the secondary fuel filter (8) should read between 400 and 525 kPa (58 to 76 psi) during normal operating conditions under load. At low idle, fuel pressure at the filter inlet (8) should read from 400 to 435 kPa (581 to 63 psi). Fuel pressure to the cylinder head fuel gallery (6) should be as above, less the delta P across the secondary fuel filter.

Pressure drop across the secondary fuel filter is typically at least 35 kPa (5 psi) with a new filter. As the filter accumulates deposits, the pressure differential will increase. If fuel pressure in the fuel gallery (6) at the injectors decreases to approximately 69 kPa (10 psi) misfiring may occur.

An orificed check valve (4) is mounted directly at the fuel return port at the rear end of the fuel gallery in the cylinder head. The orifice maintains fuel pressure at low engine speeds, and the spring loaded check valve prevents drainback of the fuel from the head after engine shutdown.

Fuel Pressure Test
(8) Fuel pressure tap (unfiltered). (9) Fuel filter base. (10) Fuel pressure tap (filtered).

To check the unfiltered fuel pressure, remove the plug from fuel pressure tap (8). Install the connector, seal and 1U5470 Engine Pressure Group to fuel pressure tap (8) to obtain transfer pump pressure. Operate the engine. To check in the main gallery for pressure, remove the plug from fuel pressure tap (10). Install the adapter, seal and 1U5470 Engine Pressure Group to fuel pressure tap (8). Operate the engine.

NOTE: Make sure the fuel filter is clean before checking fuel pressure. A restricted fuel filter will cause lower fuel pressure at tap (10) than at tap (8).

Fuel Priming Procedure (If Equipped With Priming Pump Attachment)

If the engine fuel system is run dry, fill the fuel tank and prime (purge) the fuel system to remove air bubbles from the system.

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NOTICE

Do NOT loosen fuel lines at the fuel manifold. The fittings may be damaged and/or loss of priming pressure may occur when the fuel lines are loosened.

1. Locate the fuel priming pump red selector knob.

2. Turn red selector knob away from fuel filter base at 90 degrees. This is the PRIME position.

3. Operate the priming pump plunger to fill final filter with fuel until a resistance is felt.

NOTE: 25 to 30 pump strokes may be required to fill filter and up to 75 pump strokes may be required to fill the fuel manifold.

4. Push the plunger in and tighten clockwise by hand.

5. Turn red selector knob back to RUN position.

NOTE: The pointer should be pointing to the fuel filter base.

6. After pressurizing the fuel system, promptly crank the engine using the engine starting procedure.

NOTE: If the engine starts, but runs rough, or once started continues to misfire or smoke, further priming may be necessary to help purge fuel lines of air. Continue to run the engine at low idle until fuel flows free without pockets of air in the fuel lines and the engine runs smoothly.

Finding Top Center Position For No. 1 Piston

Top Center (TC) Bolt Location (Typical Example)
(1) Top center (TC) bolt. (2) Timing hole. (3) Flywheel housing.

NOTE: Depending on engine application, the timing hole (2) is located at either the left front face or right front face of the flywheel housing.

1. Remove plug from timing hole (2) on front of flywheel housing.

NOTE: Turn the engine with the four large bolts on the front of the crankshaft. Do not use the eight small bolts on the front of the crankshaft pulley.

2. Put 8T0292 top center (TC) bolt (1) in hole. Now turn the engine flywheel counterclockwise until the top center (TC) bolt engages with the threaded hole in the flywheel.

NOTE: If the flywheel is turned beyond the point that the top center (TC) bolt engages in the threaded hole, the flywheel must be turned clockwise approximately 30 degrees. Then turn the flywheel counterclockwise until the to center (TC) bolt engages with the threaded hole. The reason for this procedure is to make sure the backlash is removed from the gears when the No. 1 piston is put on top center.

3. Remove the valve cover.

4. The intake and exhaust valves for the No. 1 cylinder are fully closed if No. 1 piston is on the compression stroke and the rocker arms can be moved by hand. If the rocker arms cannot be moved and the valves are slightly open, the No. 1 piston is on the exhaust stroke. Make reference to charts for CRANKSHAFT POSITIONS FOR VALVE LASH SETTING to find the correct cylinder(s) to be checked/adjusted for the stroke position of the crankshaft when the top center (TC) bolt has been installed in the flywheel.

NOTE: When the actual stroke position is identified, and the other stroke position is needed, it is necessary to remove the top center (TC) bolt from the flywheel, turn the flywheel counterclockwise 360 degrees, and reinstall the top center (TC) bolt.

NOTE: The timing hole is only used for valve lash setting and to time the engine electronically with the 7X1200 timing adapter group.

Crankshaft Positions For Valve Lash Setting

3100 HEUI Diesel Truck Engine Cylinder And Valve Location

Engine Speed Measurement

Engine speed measurement is available on the display screens of the electronic service tool (ECAP or ET)

6V3121 Multitach Group

The 6V3121 Multitach Group can measure engine speed from a magnetic pickup on the flywheel housing. It also has the ability to measure engine speed from visual engine parts in rotation.

Special Instruction, SEHS7807 is with the 6V3121 Multitach Group and gives instructions for the test procedure.

The 1U6602 Tachometer Group is a phototach for general use. The 1U6602 Tachometer Group is a phototach only and reads only the basic input frequency (1 pulse per revolution per piece of reflective tape) on any visible rotating part. The 1U6602 Tachometer Group does not replace the 6V3121 Multitach Group.

Special Instruction, SEHS8854 is with the 1U6602 Tachometer Group and gives instructions for its use.

NOTE: Engine speed measurement can be set with the electronic service tool. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Engine Speed/Timing Calibration.

Air Inlet And Exhaust System

Restriction Of Air Inlet And Exhaust

There will be a reduction of horsepower and efficiency of the engine if there is a restriction in the air inlet or exhaust system.

Air flow through the air cleaner must not have a restriction (negative pressure difference measurement between atmospheric air and air that has gone through air cleaner) of more than 6.22 kPa (25 inches of water).

Back pressure from the exhaust (pressure difference measurement between exhaust at outlet elbow and atmospheric air) must not be more than 10.0 kPa (40 inches of water).

Measurement Of Pressure In Inlet Manifold

The efficiency of an engine can be checked by making a comparison of the pressure in the inlet manifold with the specifications given in the TIM (Technical Marketing Information). This test is used when there is a decrease of horsepower from the engine, yet there is no real sign of a problem with the engine. Development of this information is done with these conditions:

* 737 mm (29 in) of mercury barometric pressure (dry).

* 29°C (85°F) outside air temperature.

* 35 PI rated fuel.

Any change from these conditions can change the pressure in the inlet manifold. Outside air that has higher temperature and lower barometric pressure than given above will cause a lower horsepower and a lower inlet manifold pressure measurement than given in the TMI. Outside air that has a lower temperature and a higher barometric pressure will cause higher horsepower and a higher inlet manifold pressure measurement.

A difference in fuel API rating will also change horsepower and the pressure in the inlet manifold. If the fuel is rated above 35 API, pressure in the inlet manifold can be less than given in TMI. If the fuel is rated below 35 API, the pressure in the inlet manifold can be more than given in TMI. Fuel API rating can be easily checked using the 1P7408 Thermo-Hydrometer. Instructions are given in Special instruction SEHS8874. BE SURE THAT THE AIR INLET OR EXHAUST DOES NOT HAVE A RESTRICTION WHEN MAKING A CHECK OF PRESSURE IN THE INLET MANIFOLD.

1U5470 Engine Pressure Group

Pressure Test Location
(1) Plug.

To check the inlet manifold pressure, remove one of the plugs (1) on top of inlet manifold. Connect the adapter, seal, reducing bushing, and 1U5470 Engine Pressure Group to this opening.

The 1U5470 Engine Pressure Group has a gauge to read pressure in the inlet manifold. Special Instruction, SEHS8524, is with the tool group and gives instruction for its use.

Exhaust Temperature

Temperature of an exhaust manifold port, when the engine runs at low idle speed, can be an indication of the condition of a unit injector, low temperature at an exhaust manifold port is an indication of no fuel to the cylinder. This could be caused by an inoperative unit injector pump. Exceedingly high temperatures at an exhaust manifold can be an indication of too much fuel to the cylinder, caused by a malfunctioning unit injector pump.

Use the 1U8865 Infrared Thermometer to check exhaust temperature. The Operator's Manual, NEHS0510, for the 1U8865 Infrared Thermometer gives complete operating and maintenance instructions for this tool.

Air-to-Air Aftercooled Systems

Visual Inspection

Inspect all air lines, hoses and gasket connections at each oil change. Make sure the constant torque hose clamps are tightened to the correct torque. Check the truck manufacturer's specifications for the correct torque. Check welded joints for cracks and make sure all brackets are tightened in position and are in good condition. Use compressed air to clean cooler core blockage caused by debris or dust. Inspect the cooler core fins for damage, debris or salt corrosion. Use a stainless steel brush with soap and water to remove corrosion.

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Pressure air can cause personal injury.

When using pressure air for cleaning, wear a protective face shield, protective clothing and protective shoes.

NOTE: When air-to-air aftercooler system parts are repaired and/or replaced, a leak test is recommended.

The use of winter fronts or shutters is discouraged with air-to-air aftercooled systems. Winter fronts can only be used on truck models where tests have shown that the engine jacket water will overheat before the inlet manifold air temperature is excessive. On these trucks, sensors and gauges or alarms are installed to indicate engine operating conditions before excessive inlet manifold air temperatures are reached. Check with the truck manufacturer on winter front and shutter application.

Air System Restriction

Pressure measurements should be taken at the turbocharger outlet and at the inlet manifold. When the total pressure drop of the charged air system at maximum air flow exceeds 13.5 kPa (4 inches of Hg), the air lines and cooler core must be inspected for internal restriction and cleaned, repaired or replaced as necessary.

Turbocharger Failure

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Pressure air can cause personal injury.
When using pressure air for cleaning, wear a protective face shield, protective clothing and protective shoes.

The maximum air pressure must be below 205 kPa (30 psi) for cleaning purposes.

If a turbocharger failure occurs, remove the air-to-air cooler core and flush internally with a solvent that removes oil and other foreign substances. Shake cooler to eliminate any trapped debris. Wash with hot, soapy water; rinse thoroughly with clean water; and blow dry with compressed air in reverse direction of normal air flow. Carefully inspect the system to make sure it is clean.

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NOTICE

Do not use caustic cleaners or damage to the aftercooler core will result.

Inlet Manifold Pressure

Normal inlet manifold pressure with high exhaust temperature can be caused by cooler core fin blockage. Clean the cooler core fins, see Visual Inspection for the cleaning procedure to use. Low inlet manifold pressure and high exhaust manifold temperature can be caused by any of the conditions that follow:

1. A plugged air cleaner. Clean or replace the air cleaner as needed.

2. A blockage in the air lines between the air cleaner and turbocharger. All restrictions must be removed.

3. Cooler core leakage. Pressure test the cooler core, see Aftercooler Core Leakage for the correct procedure to use and repair or replace parts as needed.

4. Leakage from the pressure side of the induction system. Check and repair leaks.

5. Inlet manifold leak. Check for loose, missing and damaged fittings or plugs. Also check the manifold to cylinder head gaskets.

Aftercooler Core Leakage

Using FT1984 Air-to-Air Aftercooler Test Group
(1) Regulator and valve assembly. (2) Nipple. (3) Relief valve. (4) Tee. (5) Coupler. (6) Aftercooler. (7) Dust plug. (8) Dust plug. (9) Chain.

A low power problem in the engine can be the result of aftercooler leakage. Low power, low boost pressure, black smoke, and/or high exhaust temperature can be the result of an aftercooler system leakage.

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NOTICE

Remove all air leaks from the system to prevent engine damage. In some operating conditions, the engine can pull a manifold vacuum for short periods of time. A leak in the aftercooler or air lines can let dirt and other foreign material into the engine and cause rapid wear and/or damage to engine parts.

A large cooler core leak often can be found by making a visual inspection. To check for smaller leaks, use the following procedure:

1. Disconnect the air pipes from the inlet and outlet side of the aftercooler core.

2. Install couplers (5) and dust plugs (7) & (8) from the FT1984 Air-to-Air Aftercooler Test Group as shown on each side of the aftercooler core. Installation of additional hose clamps on hump hoses is recommended to prevent the hoses from bulging while the aftercooler core is being pressurized.

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Dust plug chains (9) must be installed to the aftercooler core or the radiator brackets to prevent possible injury while testing. Do not stand in front of the dust plugs while testing.

3. Install regulator and valve assembly (1) on the outlet side of the aftercooler. Attach air supply.

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NOTICE

Do not use more than 240 kPa (35 psi) air pressure or damage to the aftercooler core can be the result.

4. Open air valve and pressurize the aftercooler to 205 kPa (30 psi). Shut off air supply.

5. Inspect all connections for air leakage.

6. System pressure should not drop more than 35 kPa (5 psi) in 15 seconds.

7. If the pressure drop is more than specified, use a solution of soap and water to check all areas of possible leakage and look for air bubbles. Replace hoses or repair the aftercooler core as needed.

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To help prevent personal injury when the tooling is removed, relieve all pressure in the system slowly by using air regulator and valve assembly (1).

8. After testing, remove FT Tooling and connect air pipes on each side of the aftercooler.

Dynamometer Test

Air-to-air aftercooled chassis dynamometer tests, in hot ambient temperatures, can add a greater heat load to the jacket water cooling system, therefore the jacket water cooling system temperature must be monitored. Also, monitor the inlet air temperature as it may need a power correction factor along with fuel API, fuel temperature and barometric pressure.

For engine dynamometer tests, use the FT1438 Dynamometer Testing Aftercooler. FT1438 provides an air to water aftercooler to control the inlet air temperature to 43°C (110°F).

Engine Blow-By (Air Flow)

Pistons or rings that have damage can be the cause of too much pressure in the crankcase. This condition will cause the engine to run rough. There will also be more than the normal amount of fumes (blow-by) coming from the crankcase breather. The breather can then become restricted in a very short time, causing oil leakage at gaskets and seals that would not normally have leakage. Other sources of blow-by can be worn valve guides or turbocharger seal leakage.

8T2700 Indicator Group

The 8T2700 Indicator Group is used to check the amount of blow-by. The test procedure is in Special Instruction, SEHS8712.

Compression

An engine that runs rough can have a leak at the valves, or have valves that need adjustment. Removal of the head and inspection of the valves and valve seats is necessary to find those small defects that do not normally cause a problem. Repair of these problems is normally done when reconditioning the engine.

Cylinder Head

The cylinder head has valve seat inserts, valve guides and brass sleeves that can be removed when they are worn or have damage. Replacement of these components can be made with available service tool groups that are referred to in the Disassembly And Assembly, SENR6553.

Valve Lash

Valve lash is measured between the rocker arm and the valve. All lash measurements and adjustments must be made with the engine stopped, and with the valves FULLY CLOSED.

Valve Lash Check

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This engine uses high voltage to the electronic unit injectors. Do not come in contact with the unit injector terminals while the engine is running.

When the valve lash is checked, adjustment is NOT NECESSARY if the measurement is in the range given in the chart VALVE LASH CHECK: ENGINE STOPPED. If the measurement is outside this range, adjustment is necessary. See the chart for VALVE LASH SETTING: ENGINE STOPPED, and make the setting to the nominal (desired) specifications in this chart. Refer to Operation And Maintenance Manual for service interval for valve lash adjustment.

NOTE: For valve lash specifications and measurement procedure refer to Fuel System; Crankshaft Positions For Valve Lash Setting, located in this manual.

3100 HEUI Diesel Truck Engine Cylinder And Valve Location

Valve Lash Adjustment

Use the procedure that follows for adjustment of the valves:

1. Put No. 1 piston at top center (TC) position. Make reference to Finding Top Center Position For No. 1 Piston.

2. With No. 1 piston at top center position of the correct stroke, adjustment can be made to the valves as shown in the chart CRANKSHAFT POSITIONS FOR VALVE LASH SETTING in this manual.

NOTE: Before any actual adjustments are made, tap (hit lightly) each rocker arm (at top of adjustment screw) with a soft mallet to be sure that the lifter roller is seated against the camshaft base circle.

Valve Lash Adjustment
(1) Valve. (2) Rocker arm. (3) Locknut. (4) Adjustment screw.

3. Loosen the locknut (3) for the push rod adjustment screw. If there is not enough clearance for feeler gauge between rocker arm (2) and valve (1), turn the adjustment screw (4) counterclockwise to increase the valve lash.

4. Put a feeler gauge of the correct dimension between the rocker arm and valve. Turn the adjustment screw clockwise until the valve lash is set to the specifications in the chart VALVE LASH SETTING: ENGINE STOPPED.

5. After each adjustment, tighten locknut (3) to a torque of 25 ± 7 N·m (18 ± 5 lb ft) and check the adjustment again.

6. Remove the top center (TC) bolt and turn the flywheel 360 degrees in the direction of engine rotation. This will put No. 1 piston at top center (TC) position on the opposite stroke. Install the top center (TC) bolt in the flywheel.

7. With No. 1 piston at top center position on the opposite stroke, adjustment can be made to the remainder of the valves as shown in the chart CRANKSHAFT POSITIONS FOR VALVE LASH SETTING.

8. Repeat Steps 3, 4 and 5 for these valve adjustments.

9. Remove the top center (TC) bolt from the flywheel when all valve lashes have been adjusted.

Turbocharger

The turbocharger senses boost pressure which actuates the wastegate valve which will control the amount of exhaust gas that will be allowed to bypass the turbine side of the turbocharger. The speed of the turbocharger is controlled by the wastegate valve.

(1) Actuating rod. (2) Canister. (3) Line.

When the engine is operating under low boost (lug) conditions a spring pushes against a diaphragm in canister (2) and moves actuating rod (1) to close the wastegate valve which will allow the turbocharger to operate at maximum performance.

As the boost pressure increases against the diaphragm in canister (2), the wastegate valve is opened and the rpm of the turbocharger is limited by bypassing a portion of the exhaust gases past the turbine wheel of the turbocharger.

An indication of a problem with the wastegate turbocharger is:

* boost pressure is too high at full load conditions.

* boost pressure is too low at all lug conditions.

The correct pressure for the inlet manifold is given in TMI (Technical Marketing Information).

To check the operation of the wastegate valve, verify the correct Wastegate Check Pressure by referencing the letter code stamped on the wastegate lever arm to the corresponding pressure. Remove the air line and slowly apply the check pressure to the canister. DO NOT EXCEED 200 kPa (29 psi).

The actuating lever should move 0.50 ± 0.25 mm (0.020 ±0.010 in) when the external supply of air connected to the line reaches the corresponding wastegate check pressure. If the actuating lever does not move 0.50 mm (0.020 in) replace the turbine housing assembly (which includes the wastegate) or the complete turbocharger.

To check the operation of the wastegate valve, remove line (3) and slowly apply 200 kPa (29 psi) of air to canister (2). DO NOT EXCEED 200 kPa (29 psi). The actuating lever should move more than .50 mm (.020 in) when the external supply of air is connected to line (3). If the actuating lever does not move at least .50 mm (.020 in), replace the turbine housing assembly (includes wastegate), or the complete turbocharger.

NOTE: The wastegate turbine housing assembly is preset at the factory and no adjustments can be made.

Maximum rpm of the turbocharger is controlled by the boost pressure (which controls the position of the wastegate valve), the engine rating, the high idle rpm setting and the height above sea level at which the engine is operated.

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NOTICE

If the high idle rpm or the engine rating is higher than given in TMI (Technical Marketing Information) for the height above sea level at which the engine is operated, there can be damage to engine or turbocharger parts. Damage will result when increased heat and/or friction due to the higher engine output goes beyond the engine cooling and lubrication systems abilities.

Lubrication System

One of the problems in the list that follows will generally be an indication of a problem in the lubrication system for the engine.

* Too Much Oil Consumption

* Oil Pressure Is Low

* Oil Pressure Is High

* Too Much Bearing Wear

* Increased Oil Temperature

Too Much Oil Consumption

Oil Leakage On Outside Of Engine

Check for leakage at the seals at each end of the crankshaft. Look for leakage at the oil pan gasket and all lubrication system connections. Check to see if oil comes out of the crankcase breather. This can be caused by combustion gas leakage around the pistons. A dirty crankcase breather will cause high pressure in the crankcase, and this will cause gasket and seal leakage. Check for leakage at the seals at each end of the high pressure oil line. Look for leakage at the high pressure pump.

Oil Leakage Into Combustion Area Of Cylinders

Oil leakage into the combustion area of the cylinders can be the cause of blue smoke. There are four possible ways for oil leakage into the combustion area of the cylinders:

* Oil leakage between worn valve guides and valve stems.

* Worn or damaged piston rings, or dirty oil return holes in the piston.

* Worn or damaged and/or intermediate ring not installed correctly.

* Oil leakage past the seal ring in the impeller end of the turbocharger shaft.

* Oil level too high due to error in filling, mis-marked, or incorrect dipstick.

Too much oil consumption can also be the result if oil with the wrong viscosity is used. Oil with a thin viscosity can be caused by fuel leakage into the crankcase, or by increased engine temperature and results in too much oil consumption.

Measuring Engine Oil Pressure

An oil pressure gauge that has a defect can give an indication of low or high oil pressure

1U5470 Engine Pressure Group

The 1U5470 Engine Pressure Group can be used to measure the pressure in the system. This tool group has a gauge to read pressure in the oil manifold. Special Instruction, SEHS8524 is with the tool group and gives instructions for its use.

Oil Gallery Plug
(1) Plug.

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Work carefully around an engine that is running. Engine parts that are hot, or parts that are moving, can cause personal injury.

Oil pressure to the camshaft and main bearings should be checked on the side of the cylinder block at oil gallery plug (1). Install the adapter, seal, reducing bushing, and the 1U5470 Engine Pressure Group to this opening. With the engine at operating temperature (using SAE 10W30 oil), under full load condition, minimum oil pressure should be 250 kPa (36 psi). With the engine at operating temperature (using SAE 10W30 oil), at 750 to 850 rpm low idle, minimum oil pressure is 100 kPa (15 psi). With the engine at operating temperature (using SAE 10W30 oil), under full load condition, maximum oil pressure is 600 kPa (88 psi).

Engine Oil Pressure Graph

Oil Pressure Is Low

Crankcase Oil Level

Check the level of the oil in the crankcase. Add oil if needed. It is possible for the oil level to be too far below the oil pump supply tube. This will cause the oil pump not to have the ability to supply enough lubrication to the engine components, or to supply enough oil to the high pressure hydraulic pump for proper operation of the unit injectors.

Oil Pump Does Not Work Correctly

The inlet screen of the supply tube for the oil pump can have a restriction. This will cause cavitation (low pressure bubbles suddenly made in liquids by mechanical forces) and a loss of oil pressure. Air leakage in the supply side of the oil pump will also cause cavitation and loss of oil pressure. If the bypass valve for the oil pump is held in the open (unseated) position, the lubrication system cannot get to maximum pressure. Oil pump gears that have too much wear will cause a reduction in oil pressure.

Oil Filter Bypass Valve

If the bypass valve for the oil filter is held in the open position (unseated) because the oil filter has a restriction, a reduction in oil pressure can result. To correct this problem, remove and clean the bypass valve and bypass valve bore. Install a new Caterpillar oil filter to be sure that no more debris makes the bypass valve stay open.

Too Much Clearance At Engine Bearings Or Open Lubrication System (Broken Or Disconnected Oil Line Or Passage)

Components that are worn and have too much bearing clearance can cause oil pressure to be low. Low oil pressure can also be caused by an oil line or oil passage that is open, broken or disconnected.

Piston Cooling Jet Tube

More than one type cooling jet is in use, and they are not interchangeable. Follow the engine arrangement to be sure that correct parts are being installed.

When the engine is operated, cooling jets direct oil toward the bottom of the piston to cool the piston and also provide lubrication for the piston pin. If a cooling jet is broken, plugged or installed wrong, seizure of the piston will be caused in a very short time.

Oil Pressure Is High

Oil pressure will be high if the bypass valve for the oil pump cannot move from the closed position.

Too Much Bearing Wear

When some components of the engine show bearing wear in a short time, the cause can be a restriction in an oil passage.

If the gauge for oil pressure shows enough oil pressure, but a component is worn because it cannot get enough lubrication, look at the passage for oil supply to the component. A restriction in a supply passage will not let enough lubrication get to a component, and this will cause early wear.

Increased Oil Temperature

With the engine at operating temperature (using SAE 10W30 oil), the maximum oil temperature is 115°C (239°F)

Look for a restriction in the oil passages of the oil cooler. If the oil cooler has a restriction, the oil temperature will be higher than normal when the engine is operated. A restriction only in the oil cooler will not cause the engine oil pressure to be at a low level.

Also check the oil cooler bypass valve to see if it is held in the open position (unseated). This condition will let the oil through the valve instead of the oil cooler, and oil temperature will increase.

Gauges For Oil Pressure

An oil pressure gauge or a sender that has a defect can give an indication of low or high oil pressure.

The 1U5470 Engine Pressure Group can be used to make a comparison with instrument panel gauges.

The 1U5470 Engine Pressure Group can be used to measure the pressure in the system. This tool group has a gauge to read pressure in the oil manifold. Special Instruction, SEHS8907 is with the tool group and gives instructions for its use.

Cooling System

These engines have a pressure type cooling system. A pressure type cooling system gives two advantages. The first advantage is that the cooling system can have safe operation at a temperature that is higher than the normal boiling (steam) point of water. The second advantage is that this type system prevents cavitation (low pressure bubbles suddenly made in liquids by mechanical forces) in the water pump. With this type system, it is more difficult for an air or steam pocket to be made in the cooling system.

The cause for increased engine temperature is generally because regular inspections of the cooling system were not made. Make a visual inspection of the cooling system before a test is made with test equipment.

Visual Inspection Of The Cooling System

1. Check coolant level in the cooling system.

2. Look for leaks in the system.

3. Look for bent radiator fins. Be sure that air flow through the radiator does not have a restriction.

4. Inspect the drive belts for the fan.

5. Check for damage to the fan blades.

6. Look for air or combustion gas in the cooling system.

7. Inspect the filler cap and the surface that seals the cap. This surface must be clean.

Testing The Cooling System

Remember that temperature and pressure work together. When a diagnosis is made of a cooling system problem, temperature and pressure must both be checked. Cooling system pressure will have an effect on coolant boiling temperatures. For an example, look at the chart to see the effect of pressure and height above sea level on the boiling (steam) point of water.

Test Tools For Cooling System

8T0470 Thermistor Thermometer Group

The 8T0470 Thermistor Thermometer Group is used in the diagnosis of overheating (engine hotter than normal) or over cooling (engine cooler than normal) problems. This group can be used to check temperatures in several different parts of the cooling system. The testing procedure is in Special Instruction, SEHS8446.

8T2700 Blow-by/Air Flow Indicator Group

8T2700 Indicator Group

The 8T2700 Blow-by/Air Flow Indicator Group is used to check the air flow through the radiator core. The test procedure is in Special Instruction, SEHS8712.

6V3121 Multitach Group or 1U6602 Tachometer Group (Photo-Tachometer)

6V3121 Multitach Group

The 6V3121 Multitach Group is used to check the fan speed. The testing procedure is in Special Instruction, SEHS7807.

The 6V3121 Multitach Group can measure engine speed from a magnetic pickup on the flywheel housing. It also has the ability to measure engine speed from visual engine parts in rotation.

Special Instruction, SEHS7807 is with the 6V3121 Multitach Group and gives instructions for the test procedure.

1U6602 Tachometer Group (Photo-Tachometer)

The 1U6602 Tachometer Group is a hand held phototach for general use. The 1U6602 Tachometer Group is a phototach only and reads only the basic input frequency (one pulse per revolution per piece of reflective tape) on any visible rotating part. The 1U6602 Tachometer Group does not replace the 6V3121 Multitach Group.

Special Instruction, SEHS8854 is with the 1U6602 Tachometer Group and gives instructions for its use.

9S8140 Cooling System Pressurizing Pump Group

The 9S8140 Cooling System Pressurizing Pump Group is used to test pressure caps and to pressure check the cooling system for leaks.

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DO NOT loosen the filler or pressure cap on a hot engine. Steam or hot coolant can cause severe burns.

Checking Pressure Cap

One cause for a pressure loss in the cooling system can be a defective seal on the radiator pressure cap.

Typical Schematic Of Pressure Cap
(A) Sealing surface of cap and radiator.

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DO NOT loosen the filler or pressure cap on a hot engine. Steam or hot coolant can cause severe burns.

After the engine is cool, loosen the pressure cap and let the pressure out of the cooling system. Then remove the pressure cap.

Inspect the pressure cap carefully. Look for damage to the seal or to the surface that seals. Any foreign material or deposits on the cap, seal or surface that seals, must be removed.

9S8140 Cooling System Pressurizing Pump Group

The 9S8140 Cooling System Pressurizing Pump Group is used to test pressure caps and to pressure check the cooling system for leaks.

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DO NOT loosen the filler or pressure cap on a hot engine. Steam or hot coolant can cause severe burns.

To check the pressure cap for the pressure that makes the pressure cap open, use the procedure that follows:

1. Remove the pressure cap from the radiator.

2. Put the pressure cap on the 9S8140 Cooling System Pressurizing Pump Group.

3. Look at the gauge for the exact pressure that makes the pressure cap open.

4. Make a comparison of the reading on the gauge with the correct pressure at which the pressure cap must open.

5. If the pressure cap is defective, install a new pressure cap.

Testing Radiator And Cooling System For Leaks

To test the radiator and cooling system for leaks, use the procedure that follows:

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DO NOT loosen the filler or pressure cap on a hot engine. Steam or hot coolant can cause severe burns.

1. Remove the pressure cap from the radiator.

2. Make sure the coolant is over the top of the radiator core.

3. Put the 9S8140 Cooling System Pressurizing Pump Group on the radiator.

4. Get the pressure reading on the gauge to 20 kPa (3 psi) more than the pressure on the pressure cap.

5. Check the radiator for outside leakage.

6. Check all connections and hoses for the cooling system for outside leakage.

7. If you do not see any outside leakage and the pressure reading on the gauge is still the same after 5 minutes, the radiator and cooling system does not have leakage. If the reading on the gauge goes down and you do not see any leakage, there is leakage on the inside of the cooling system. Make repairs as necessary.

Water Temperature Gauge Test

Check the accuracy of the water temperature gauge if either of the conditions that follow are found:

* The gauge reads normal, but the engine is too hot and a loss of coolant is found.

* The gauge shows that the engine is hot, but no loss of coolant can be found.

Coolant temperature can also be read on the display screens of the electronic service tool (ECAP or ET)

Test Location
(1) Plug. (2). Water temperature regulator housing.

Remove plug (1) and install the adapter, seal, and the 8T0470 Thermistor Thermometer Group or the 2F7112 Thermometer. A temperature gauge of known accuracy can also be used to make this check.

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Work carefully around an engine that is running. Engine parts that are hot, or parts that are moving, can cause personal injury.

Start the engine and run it until the temperature reaches the desired range according to the test thermometer. If necessary, put a cover over part of the radiator or cause a restriction of the coolant flow. The reading on the gauge for water temperature should agree with test thermometer within the tolerance range of the gauge.

Water Temperature Regulator Test

1. Remove the regulator from the engine.

2. Heat water in a pan until the temperature is 94°C (202°F). Move the water around in the pan to make it all the same temperature.

3. Hang the regulator in the pan of water. The regulator must be below the surface of the water and it must be away from the sides and bottom of the pan.

4. Keep the water at the correct temperature for ten minutes.

5. After ten minutes, remove the regulator and immediately measure the distance the regulator has opened. Refer to the Specifications in this service manual for the minimum opening length.

6. If the distance is less than the minimum opening length from the specifications section in this service manual then replace the regulator.

Water Pump Pressure Check

Water Pump Group
(1) Port (alternate heater supply). (2) Port (for engine diagnosis). (3) Ports (heater return).

The pressure rise (increase in pressure or pressure differential) tells if the water pump is operating correctly. Measure the pressure rise across or between port (1) or port (2) and one of two ports (3). Ports (1) and (2) represent water pump outlet pressure. Ports (3) represent water pump inlet pressure (suction). With the engine at operating temperature, under full load condition, the pressure rise must be a minimum of 80 kPa (12 psi).

Belt Tension Chart

Basic Block

Connecting Rod Bearings

The connection rod bearings fit tightly in the bore in the rod. If bearing joints or backs are worn (fretted), check bore size. This can be an indication of wear because of a loose fit.

Connecting rod bearings are available with 0.25 mm (.010 in) and 0.50 mm (.020 in) smaller inside diameter than the original size bearings. These bearings are for crankshafts that have been ground (made smaller than original size).

Main Bearings

Main bearings are available with a larger outside diameter than the original size bearings. These bearings are for cylinder blocks that have had the bore for the main bearings "bored" (made larger than the original size). The size available is 0.50 mm (.020 in) larger outside diameter than the original size bearings.

Main bearings are available with a smaller inside diameter than the original size bearings. These bearings are for cylinder blocks that have a crankshaft that has been ground (made smaller than original size). Main bearings are available with 0.25 mm (.010 in) and 0.50 mm (.020 in) smaller inside diameter than the original size bearings.

Cylinder Block

The bore in the block for main bearings can be checked with the main bearing caps installed without bearings. Tighten the nuts that hold the caps to the torque shown in the Specifications section. Alignment error in the bores must not be more than 0.08 mm (.003 in).

The 1P3537 Dial Bore Gauge Group can be used to check the size of the bore. Special Instruction, GMG00981 is with the group.

1P3537 Dial Bore Gauge Group

Flywheel And Flywheel Housing

Face Run Out (Axial Eccentricity) Of The Flywheel Housing

8T5096 Dial Indicator Group Installed
(Typical Example)

If any method other than given here is used, always remember bearing clearance must be removed to get correct measurements.

1. Fasten a dial indicator to the flywheel so the anvil of the indicator will touch the face of the flywheel housing.

2. Put a force on the crankshaft toward the rear before the indicator is read at each point.

Checking Face Runout Of The Flywheel Housing

3. With dial indicator set at "0" (zero) at location (A), turn the flywheel and read the indicator at locations (B), (C) and (D).

4. The difference between lower and higher measurements taken at all four points must not be more than 0.38 mm (.015 in), which is the maximum permissible face run out (axial eccentricity) of the flywheel housing.

Bore Runout (Radial Eccentricity) Of The Flywheel Housing

1. Fasten the dial indicator as shown so the anvil of the indicator will touch the bore of the flywheel housing.

2. With the dial indicator in position at (C), adjust the dial indicator to "0" (zero). Push the crankshaft up against the top of the bearing. Write the measurement for bearing clearance on line 1 in column (C) in the Chart For Dial Indicator Measurements.

8T5096 Dial Indicator Group Installed
(Typical Example)

NOTE: Write the dial indicator measurements with their positive (+) and negative (-) notation (signs). This notation is necessary for making the calculations in the chart correctly.

3. Divide the measurement from Step 2 by 2. Write this number on line 1 in columns (B) & (D).

4. Turn the flywheel to put the dial indicator at (A). Adjust the dial indicator to "0" (zero).

5. Turn the flywheel counterclockwise to put the dial indicator at (B). Write the measurements in the chart.

Checking Bore Runout Of The Flywheel Housing

6. Turn the flywheel counterclockwise to put the dial indicator at (C). Write the measurement in the chart.

7. Turn the flywheel counterclockwise to put the dial indicator at (D). Write the measurement in the chart.

8. Add lines I & II by columns.

9. Subtract the smaller number from the larger number in line III in columns (B) & (D). The result is the horizontal eccentricity (out of round). Line III, column (C) is the vertical eccentricity.

10. On the graph for total eccentricity, find the point of intersection of the lines for vertical eccentricity and horizontal eccentricity.

11. If the point of intersection is in the range marked "Acceptable", the bore is in alignment. If the point of intersection is in the range marked "Not Acceptable", the flywheel housing must be changed.

Graph For Total Eccentricity
(1) Total Vertical Eccentricity [mm (in)]. (2) Total Horizontal Eccentricity [mm (in)]. (3) Acceptable. (4) Not Acceptable.

Face Runout (Axial Eccentricity) Of The Flywheel

1. Install the dial indicator as shown. Always put a force on the crankshaft in the same direction before the indicator is read so the crankshaft end clearance (movement) is always removed.

Checking Face Runout Of The Flywheel
(Typical Example)

2. Set the dial indicator to read "0" (zero).

3. Turn the flywheel and read the indicator every 90 degrees.

4. The difference between the lower and higher measurements taken at all four points must not be more than 0.15 mm (.006 in), which is the maximum permissible face runout (axial eccentricity) of the flywheel.

Bore Runout (Radial Eccentricity) Of The Flywheel

Checking Bore Runout Of The Flywheel (Typical Example)
(1) 7H1945 Holding Rod (2) 7H1645 Holding Rod (3) 7H1942 Indicator (4) 7H1940 Universal Attachment

1. Install the dial indicator (3) and make an adjustment of the universal attachment (4) so it makes contact as shown.

2. Set the dial indicator to read "0" (zero).

3. Turn the flywheel and read the indicator every 90 degrees.

4. The difference between the lower and higher measurements taken at all four points must not be more than 0.15 mm (.006 in), which is the maximum permissible bore runout (radial eccentricity) of the flywheel.

5. Runout (eccentricity) of the bore for the pilot bearing for the flywheel clutch, must not exceed 0.13 mm (.005 in).

Checking Flywheel Clutch Pilot Bearing Bore

Vibration Damper

Damage to or failure of the damper will increase vibrations and result in damage of the crankshaft.

Rubber Damper (If Equipped)

Rubber Vibration Assembly
(1) Crankshaft. (2) Hub. (3) Rubber (4) Ring. (5) Alignment marks. If the damper is damaged, or if the bolt holes in the damper are loose fitting, replace the damper. Replacement of the damper is also needed at the time of a crankshaft failure due to torsional forces.

The vibration damper has alignment marks on the hub and the ring. These marks give an indication of the condition of the vibration damper. If the marks are not in alignment, the rubber part (between the ring and the hub) of the vibration damper has had a separation from the ring and/or hub. If the marks are not in alignment, install a new vibration damper.

A used vibration damper can have a visual wobble (movement to the front and then to the rear when in rotation) on the outer ring and still not need replacement, because some wobble of the outer ring is normal. To see if the amount of wobble is acceptable, or replacement is necessary, check the damper with the procedure that follows:

1. Install a dial indicator, contact point and other parts necessary to hold the dial indicator stationary. The contact point must be perpendicular (at a 90 degree angle) to the face of the outer ring of the damper, and must make contact approximately at the center of the outer ring.

2. Push on the front end of the crankshaft so the end play (free movement on the centerline) is removed. Keep the crankshaft pushed back until the measurements are finished.

3. Adjust the dial indicator to zero.

4. Turn the crankshaft 360 degrees and watch the dial indicator. A total indicator reading of 0.00 to 2.03 mm (.000 to .080 in) is acceptable.

Viscous Damper (If Equipped)

If the damper is leaking, bent or damaged, or if the bolt holes in the damper are loose fitting, replace the damper. Replacement of the damper is also needed at the time of a crankshaft failure due to torsional forces.

Viscous Vibration Damper
(1) Crankshaft. (2) Weight. (3) Case.

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NOTICE

Inspect the viscous damper for signs of leakage or a dented (damaged) case (3). Either condition can cause weight (2) to make contact with case (3) and affect damper operation.

Electrical System

Test Tools For Electrical System

Most of the tests of the electrical system can be done on the engine. The wiring insulation must be in good condition, the wire and cable connections must be clean and tight, and the battery must be fully charged. If the on-engine test shows a defect in a component, remove the component for more testing.

The service manual Testing And Adjusting Electrical Components, REG00636 has complete specifications and procedures for the components of the starting circuit and the charging circuit.

4C4911 Battery Load Tester

The 4C4911 Battery Load Tester is a portable unit in a metal case for use under field conditions and high temperatures. It can be used to load test all 6, 8 and 12V batteries. This tester has two heavy-duty load cables that can easily be fastened to the battery terminals, and a load adjustment knob on the top permits the current being drawn from the battery to be adjusted to a maximum of 1000 amperes. The tester is cooled by an internal fan that is automatically activated when a load is applied.

The tester has a built in Liquid Crystal Display (LCD) digital voltmeter and amperage meter. The digital voltmeter accurately measures the battery voltage at the battery, through tracer wires buried inside the load cables. The digital amperage meter accurately displays the current being drawn from the battery under test.

NOTE: Make reference to Operating Manual, SEHS9249 for more complete information for use of the 4C4911 Battery Load Tester.

8T0900 AC/DC Clamp-On Ammeter

The 8T0900 AC/DC Clamp-On Ammeter is a completely portable, self-contained instrument that allows electrical current measurements to be made without breaking the circuit or disturbing the insulation on conductors. A digital display is located on the ammeter for reading current directly in a range from 1 to 1200 amperes. If an optional 6V6014 Cable is connected between this ammeter and one of the digital multimeters, current readings of less than 1 ammeter can then be read directly from the display of the multimeter.

A lever is used to open the jaws over the conductor [up to a diameter of 19 mm (.75 in)], and the spring loaded jaws are then closed around the conductor for current measurement. A trigger switch that can be locked in the ON or OFF position is used to turn on the ammeter. When the turn-on trigger is released, the last current reading is held on the display for five seconds. This allows accurate measurements to be taken in limited access areas where the digital display is not visible to the operator. A zero control is provided for DC operation, and power for the ammeter is supplied by batteries located inside the handle.

NOTE: Make reference to Special Instruction, SEHS8420 for more complete information for use of the 8T0900 Clamp-On Ammeter.

6V7070 Heavy-Duty Digital Multimeter

The 6V7070 Heavy-Duty Digital Multimeter is a completely portable, hand held instrument with a digital display. This multimeter is built with extra protection against damage in field applications, and is equipped with seven functions and 29 ranges. The 6V7070 Multimeter has an instant ohms indicator that permits continuity checking for fast circuit inspection. It also can be used for troubleshooting small value capacitors.

The 6V7800 Regular-duty Digital Multimeter (a low cost option to the Heavy-Duty Multimeter) is also available; however, the 6V7800 Multimeter does not have the 10A range or the instant ohms feature of the 6V7070 Multimeter.

NOTE: Make reference to Special Instruction, SEHS7734 for more complete information for use of the 6V7070 and 6V7800 Multimeters.

Battery

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Never disconnect any charging unit circuit or battery circuit cable from battery when the charging unit is operated. A spark can cause an explosion from the flammable vapor mixture of hydrogen and oxygen that is released from the electrolyte through the battery outlets. Injury to personnel can be the result.

The battery circuit is an electrical load on the charging unit. The load is variable because of the condition of the charge in the battery. Damage to the charging unit will result if the connections (either positive or negative) between the battery and charging unit are broken while the charging unit is in operation. This is because the battery load is lost and there is an increase in charging voltage. High voltage will damage, not only the charging unit, but also the regulator and other electrical components.

Use the 4C4911 Battery Load Tester, the 8T0900 Clamp-On Ammeter and the 6V7070 Multimeter to load test a battery that does not hold a charge when in use. See Special Instruction, SEHS7633 for the correct procedure and specifications to use.

Charging System

The condition of charge in the battery at each regular inspection will show if the charging system operates correctly. An adjustment is necessary when the battery is constantly in a low condition of charge or a large amount of water is needed (more than one ounce of water per cell per week or per every 100 service hours).

When it is possible, make a test of the charging unit and voltage regulator on the engine, and use wiring and components that are a permanent part of the system. Off-engine (bench) testing will give a test of the charging unit and voltage regulator operation. This testing will give an indication of needed repair. After repairs are made, again make a test to give proof that the units are repaired to their original condition of operation.

Before the start of on-engine testing, the charging system and battery must be checked as shown in the Steps that follow:

1. Battery must be at least 75 percent (1.225 Sp.Gr.) fully charged and held tightly in place. The battery holder must not put too much stress on the battery.

2. Cables between the battery, starter and engine ground must be the correct size. Wires and cables must be free of corrosion and have cable support clamps to prevent stress on battery connections (terminals).

3. Leads, junctions, switches and panel instruments that have direct relation to the charging circuit must give correct circuit control.

4. Inspect the drive components for the charging unit to be sure they are free of grease and oil and have the ability to operate the charging unit.

Alternator

Make reference to the Specifications section of the complete service manual to find all testing specifications for the alternators and regulators.

No adjustment can be made to change the rate of charge on 24V alternator regulators. If rate of charge is not correct, a replacement of the alternator regulator is necessary.

Starting System

Use a DC Voltmeter to find starting system components which do not function.

Move the start control switch to activate the starter solenoid. Starter solenoid operation can be heard as the pinion of the starter motor is engaged with the ring gear on the engine flywheel.

If the solenoid for the starter motor will not operate, it is possible that the current from the battery did not get to the solenoid. Fasten one lead of the voltmeter to the connection (terminal) for the battery cable on the solenoid. Put the other lead to a good ground. No voltmeter reading shows there is broken circuit from the battery. More testing is necessary when there is a reading on the voltmeter.

The solenoid operation also closes the electric circuit to the motor. Connect one lead of the voltmeter to the solenoid connection (terminal) that is fastened to the motor. Put the other lead to a good ground. Activate the starter solenoid and look at the voltmeter. A reading of battery voltage shows the problem is in the motor. The motor must be removed for further testing. No reading on the voltmeter shows that the solenoid contacts do not close. This is an indication of the need for repair to the solenoid or an adjustment to be made to the starter pinion clearance.

Make a test with one voltmeter lead fastened to the connection (terminal) for the small wire at the solenoid, and the other lead to the ground. Look at the voltmeter and activate the starter solenoid. A voltmeter reading shows that the problem is in the solenoid. No voltmeter reading shows that the problem is in the start switch or the wires for the start switch.

Fasten one voltmeter lead to the start switch at the connection (terminal) for the wire from the battery. Fasten the other lead to a good ground. No voltmeter reading indicates a broken circuit from the battery. Make a check of the circuit breaker and wiring. If there is a voltmeter reading, the problem is in the start switch or in the wires for the start switch.

A starter motor that operates too slow can have an overload because of too much friction in the engine being started. Slow operation of the starter motor can also be caused by short circuit, loose connections and/or dirt in the motor.

To test for correct output of starter motors and starter solenoid, make reference to the Specifications section of the complete service manual.