3408 & 3408B DIESEL TRUCK ENGINE Caterpillar

Troubleshooting Problems

Usage:

Problem 1: Engine Will Not Start (Crankshaft Does Not Turn)

Probable Cause:

1. Battery Has Low Output Voltage:

Check battery voltage. If battery voltage is less than 8 volts for a 12 volt system, or 16 volts for a 24 volt system, put a charge to the battery. Check alternator charging output. Load test the battery as shown in Testing and Adjusting section.

If the battery will not hold a charge, or if the charging system is not working correctly, make repairs or replacements as necessary.

2. Wiring Or Key Start Switch Defective:

With the ignition switch in START position, check voltage at switch connection on starter solenoid. If there is no voltage, or if the voltage is low at this connection, check wiring, connections, ignition switch, and magnetic switch. Make repairs or replacements as needed.

3. Battery To Starter Cables Or Connections Defective:

With ignition switch in the START position, check voltage at connection of battery cable to starter. If there is no voltage, or if the voltage is low at this connection and there is good voltage at the battery, check for bad cable or connection between the battery and starter.

4. Starter Motor Solenoid Defective:

Remove and replace a solenoid which does not work when voltage is correct at both the battery and ignition switch connections.

5. Starter Motor Defective:

If the solenoid works and the starter motor does not turn the crankshaft, the starter motor is bad. Before removing the starter motor, turn the crankshaft by hand to be sure a mechanical failure inside the engine, transmission, or power take-off is not preventing the crankshaft from turning. If the crankshaft turns freely by hand, engage the starter motor again. If the starter motor still will not work, remove and repair it, or install a new starter motor.

6. Transmission Or Power Take-Off (If So Equipped) Problem:

If the crankshaft can not be turned by hand, disconnect the transmission and power take-off. If the crankshaft will now turn, find the cause of the problem in the transmission or power take-off and make the necessary corrections.

7. Problem Inside The Engine Prevents Crankshaft From Turning

If the crankshaft can not be turned after disconnecting the transmission and power take-off remove the fuel nozzles 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 inside problems. Some of these inside problems are bearing seizure, and valves making contact with pistons.

Problem 2: Engine Will Not Start (Crankshaft Turns Too Slowly)

Probable Cause:

1. Starter Motor Turns Too Slow:

The causes can be similar or the same as those that keep the crankshaft from turning. Check the items listed in PROBLEM 1.

2. Oil Too Thick For Free Crankshaft Rotation:

Use SAE 10W/30, 10W/40 grade oils for temperatures below 0°C (32°F). At temperatures below -23°C (-10°F) it may be necessary to warm the oil for free crankshaft rotation.

Problem 3: Engine Will Not Start (Crankshaft Turns Freely)

Probable Cause:

Exhaust Smoke Can Be See While Starting

1. Cold Outside Temperatures:

It can be necessary to use starting aids, or to heat engine oil or coolant at temperatures below -12°C (10°F) for D.I. engines and 10°C (50°F) for P.C. engines.

2. 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. If the engine will not start, loosen a fuel injection line nut at the valve cover base. With the governor lever in the shutoff position, crank the engine until the flow of fuel from the loosened fuel injection line is free of air. Tighten the fuel line nut. Start the engine, if the engine still does not run smooth or releases a large amount of white smoke, loosen the fuel line nuts one at a time at the valve cover base until the fuel that comes out is free of air. Tighten the fuel line nuts. If the air cannot be removed in this way, put 35 kPa (5 psi) or air pressure to the fuel tank.

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NOTICE

Do not use more than 55 kPa (8 psi) of air pressure in the fuel tank or damage to the tank may result.

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. 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.

3. Low Quality Fuel:

Remove a small amount of fuel from the tank and check for water in the fuel. If there is water in the fuel, remove fuel from the tank until it is free of water and fill with a good quality fuel. Change the fuel filter and "prime" (remove the air and/or low quality fuel from the fuel system) the fuel system with the fuel priming pump. If there is no water in the fuel, prime and start the engine by using an outside source of fuel. If engine starts correctly using different fuel, remove all fuel from the tank and fill with good quality fuel. Prime the fuel system if necessary.

4. Fuel Transfer Pump:

At starting rpm, the minimum fuel pressure from fuel transfer pump must be 35 kPa (5 psi). If fuel pressure is less than 35 kPa (5 psi), change the fuel filter element. Look for air in the fuel system. If fuel pressure is still low, install a new fuel transfer pump.

5. Fuel Injection Timing Not Correct:

Check and make necessary adjustments as given in the Testing And Adjusting section of this Service Manual.

6. Valve Adjustment Not Correct:

Check and make necessary adjustments as given in the Testing And Adjusting section of this Service Manual. Intake valve clearance is 0.38 mm (.015 in.) and exhaust valve clearance is 0.76 mm (.030 in.).

7. Bad Fuel Nozzle(s):

Remove the fuel nozzles and test as in the Testing And Adjusting section of this Service Manual.

8. Low Compression:

See Engine Misfires Or Runs Rough.

Exhaust Smoke Cannot Be Seen While Starting

9. No Fuel In Tank(s):

Check fuel level visually (do not use the fuel gauge only). Be sure tank selection valve is open to the tank with fuel in it. Be sure valve in fuel line between the tanks is open.

10. No Fuel From Fuel Injection Pump:

Loosen a fuel injection line nut at the valve cover base. With ignition switch in the ON position and accelerator in the FUEL ON position, turn the engine with the starter to be sure there is no fuel from the fuel injection pump. To find the cause for no fuel, follow Steps (a) through (d) until the problem is corrected.

a. Prime the low pressure side of the fuel system with the priming pump.

b. Check the shutoff solenoid. Remove the cover on the governor and check the plunger. Plunger should be fully extended to allow full rack travel. If rack travel is restricted, adjust the plunger or replace the solenoid.

c. If you are not using a good quality of fuel at temperatures below -12°C (10°F), it is possible that the fuel in the system can "wax" (not have correct flow characteristics) and cause a restriction in the fuel system. Install a new fuel filter. It may be necessary to drain the complete fuel system and replace with a No. 1 grade of fuel.

d. Check for fuel supply line restriction by removing the fuel supply line for the fuel filter base. Put 35 kPa (5 psi) of air pressure to the fuel tank.

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NOTICE

Do not use more than 55 kPa (8 psi) of air pressure in the fuel tank or damage to the tank may result.

If there is no fuel, or only a weak flow of fuel from the fuel supply line, there is a restriction in the fuel supply line and/or the fuel tank.

11. Exhaust System Not Open:

Loosen the exhaust pipe from the exhaust manifold. If engine will now start, check the exhaust system for damage and/or restrictions.

Problem 4: Engine Misfires Or Runs Rough

Probable Cause:

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, sticking, binding or defective fuel bypass valve. Check fuel pressure. The outlet pressure of the fuel transfer pump is 230 ± 35 kPa (33 ± 5 psi) at full load speed.

If fuel pressure is lower than 140 kPa (20 psi), install a new filter element. If fuel pressure is still low, install a new fuel transfer pump.

2. Air in Fuel System:

Find the air leak in the fuel system and correct it. If air is in the fuel system, it will probably get in on the suction side of fuel transfer pump.

3. Leak or Break in Fuel Line Between Injection Pump and Injection Valve:

Install a new fuel line.

4. Wrong Valve Clearance:

Make adjustment according to the Subject, VALVE CLEARANCE SETTING.

5. Defect in Fuel Injection Valve(s) or Injection Pump(s):

Run at rpm that causes engine to misfire the most or run the roughest. Then loosen a fuel injection line nut at the valve cover base for each cylinder, one at a time. Find the cylinder where a loosened fuel line nut does not change the way the engine runs. Test the injection pump and injection valve for that cylinder. Install new parts where needed.

6. Wrong Fuel Injection Timing:

Make adjustment to timing.

7. Bent or Broken Push Rod:

Replacement of push rod is necessary.

8. Fuel Has "Cloud Point" Higher Than Atmospheric Temperature ("Cloud Point" = Temperature Which Makes Wax Form In Fuel.):

Drain the fuel tank, lines, and fuel injection pump housing. Change the fuel filter. Fill the tank with fuel which has the correct "cloud point" and remove the air from the system with the priming pump.

9. Valve Leakage, Wear Or Damage To Pistons And/Or Piston Rings, Wear Or Damage To Cylinder Walls:

The cylinder head will have to be removed to make a visual inspection of these inside problems.

10. Cylinder Head Gasket Leakage:

Leakage at the gasket of the cylinder head can show as an outside leak or can cause loss of coolant through the radiator overflow. Remove the radiator filler cap and, with the engine running, check for air bubbles in coolant caused by exhaust gases.

11. Engine Camshaft Timing Not Correct:

Engine camshaft timing can be checked by finding the top center position for number one cylinder. See Intake Valve Timing Under Camshaft in the Specifications section.

Problem 5: Engine Stalls At Low RPM

Probable Cause:

1. Fuel Pressure is Low:

If fuel pressure is lower than 140 kPa (20 psi), install a new filter element. If fuel pressure is still low, install a new fuel transfer pump.

2. Idle rpm Too Low:

Make adjustment to governor so idle rpm is the same as given in the Fuel Setting And Related Information Fiche.

3. Defect Fuel Injection Nozzle:

Bad fuel nozzles will normally cause the engine to misfire and run rough, but can cause too much smoke with engine still running smooth. Remove the fuel nozzles. Use the procedure given in the Testing And Adjusting section to test the nozzles.

4. Engine Accessories Over Loading The Engine:

Check engine accessories for damage and correct adjustment. If necessary, disconnect the accessories and test the engine.

5. Defective Fuel Injection Pump:

An injection pump can have a good fuel flow coming from it but cause rough running because of slow timing that is caused by wear on the bottom end of the plunger. See the Testing And Adjusting section for the correct specifications and procedure to check the plungers and lifters. Fuel pumps which are severely scored from debris can cause rough running, but fuel dilution usually occurs before horsepower is affected. Low installation torque on the fuel pump retaining nut can cause misfire, rough running and low power.

6. 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. If the engine will not start, loosen a fuel injection line nut at the valve cover base and crank the engine until fuel comes out. Tighten the fuel line nut. Start the engine. If the engine still does not run smooth or releases a large amount of white smoke, loosen the fuel line nuts one at a time at the valve cover base until the fuel that comes out is free of air. Tighten the fuel line nuts. If the air can not be removed in this way, put 35 kPa (5 psi) of air pressure to the fuel tank.

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NOTICE

Do not use more than 55 kPa (8 psi) of air pressure in the fuel tank or damage to the tank may result.

Problem 6: Sudden Changes In Engine Speed (RPM)

Probable Cause:

1. Failure of Governor or Fuel Injection Pump:

Look for damaged or broken springs, linkage or other parts. Remove the governor. Check for free travel of the fuel racks. Be sure fuel injection pumps are installed correctly. Check for correct governor spring. Install new parts for those that have damage or defects.

Problem 7: Low Engine Power

NOTE: Make reference to Section I, Understanding Truck Performance Complaints, in the Truck Performance Diagnostic Guide, Form No. SEBD0808 for additional information other than engine related problems.

Probable Cause:

1. Bad Quality Or Water In Fuel:

Follow the recommendations given in Special Instruction Form No. SEHS7067, Fuel Recommendations For Caterpillar Diesel Engines. Also, Special Instruction Form No. SEHS6947 has fuel correction factors and tables.

2. Low Fuel Pressure:

Change the primary and secondary fuel filters and check to make sure the fuel lines are not plugged or damaged. If the filters or lines are not the cause, a repair or replacement of the fuel transfer pump is needed.

3. Incorrect Use Of Fuel Heater:

Fuel heaters should be turned off for warm weather operation. Fuel from the fuel transfer pump should not exceed 65°C (149°F).

4. 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. If the engine will not start, loosen a fuel injection line nut at the valve cover base and crank the engine until fuel comes out. Tighten the fuel line nut. Start the engine. If the engine still does not run smooth or releases a large amount of white smoke, loosen the fuel line nuts one at a time at the valve cover base until the fuel that comes out is free of air. Tighten the fuel line nuts. If the air can not be removed in this way, put 35 kPa (5 psi) of air pressure to the fuel tank.

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NOTICE

Do not use more than 55 kPa (8 psi) of air pressure in the fuel tank or damage to the tank may result.

5. Leaks In Inlet Air System:

Follow procedures in the Testing and Adjusting section to check inlet manifold pressure and aftercooler core leakage.

6. High Exhaust Back Pressure:

Check exhaust system for restrictions.

7. Turbocharger Has Carbon Deposits Or Other Causes Of Friction:

Inspect and repair turbocharger as necessary

8. Wrong Valve Clearance:

Check and make necessary adjustments as given in the Testing and Adjusting section. Intake valve clearance is 0.38 mm (.015 in.) and exhaust valve clearance is 0.76 mm (.030 in.).

9. Defective Fuel Injection Nozzle:

Remove the fuel nozzles. Use the procedure given in the Testing and Adjusting section to test the nozzles.

10. Defective Fuel Injection Pump:

An injection pump can have a good fuel flow coming from it but cause rough running because of slow timing that is caused by wear on the bottom end of the plunger. See the Testing and Adjusting section for the correct specifications and procedure to check the plungers and lifters. Fuel pumps which are severely scored from debris can cause rough running, but fuel dilution usually occurs before horsepower is affected. Low installation torque on the fuel pump retaining nut can cause misfire, rough running and low power.

11. Engine Accessories Over Loading The Engine:

Check engine accessories for damage and correct adjustment. If necessary, disconnect the accessories and test the engine.

12. Governor Linkage:

Make adjustment to get full travel of linkage. Install new parts for those that have damage or defects.

13. Wrong Fuel Injection Timing:

Make adjustment to timing.

14. Rack Setting Too Low:

Make reference to the Fuel Setting And Related Information Fiche.

15. Fuel Ratio Control:

Control either needs an adjustment or it is damaged and a new control is needed.

Problem 8: Too Much Vibration

Probable Cause:

1. Loose Bolt Or Nut For Pulley Or Damper:

Tighten bolt or nut.

2. Pulley Or Damper Has A Defect:

Install a new pulley or damper.

3. Engine Supports Are Loose, Worn, Or Have A Defect:

Tighten all bolts that hold engine supports. Install new components if necessary.

4. Engine Misfires Or Runs Rough:

Make Reference to Item 3.

5. Fan Blade Not In Balance:

Loosen or remove fan belts and operate engine for a short time at the rpm that the vibration was present. If vibration is not still present, make a replacement of the fan assembly.

Problem 9: Loud Combustion Noise

Probable Cause:

1. Bad Quality Or Water In Fuel:

2. Defective Fuel Injection Nozzle:

Remove the fuel nozzles. Use the procedure given in the Testing and Adjusting section to test the fuel nozzles.

3. Defective Fuel Injection Pump:

4. Wrong Fuel Injection Timing:

Make an adjustment to timing.

Problem 10: Valve Train Noise (Clicking)

Probable Cause:

1. Damage To Valve Spring(s), Locks, 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.

2. 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.

3. Too Much Valve Clearance:

Make adjustment according to the Subject, Valve Clearance Setting in the Testing And Adjusting section.

Problem 11: Oil In Cooling System

Probable Cause:

1. Defect In Core Of Engine Oil Cooler Or Transmission Oil Cooler:

Install a new engine oil cooler or transmission oil cooler. Drain and flush cooling system and refill with new coolant.

2. Defect In Spacer Plate Gasket:

Install new spacer plate gasket.

3. Failure Of Cylinder Head Gasket:

Install a new head gasket.

Problem 12: Mechanical Noise (Knock) In Engine

Probable Cause:

1. Failure Of Bearing For Connecting Rod:

Inspect the bearing for the connecting rod and the bearing surface (journal) on the crankshaft. Install new parts where necessary.

2. Damaged Timing Gears:

Install new parts where necessary.

3. Damaged Crankshaft:

Make replacement of the crankshaft.

4. Defect In Attachment:

Repair or install new components.

Problem 13: Fuel Consumption Too High

Probable Cause:

1. MPG Measurement Errors:

Follow truck high fuel consumption check list:

Miles measured correctlyFuel measured correctlyComparison to other trucksDifferent truck or engine specificationsDifferent operating loadsDifferent operating modes

2. Bad Quality Or Water In Fuel:

3. Fuel System Leaks:

Inspect the fuel system for leaks and make repairs or replacements as needed.

4. Excess Idle Time:

Shut engine off when not in use.

5. Excess Road Speed Or Operation At High Engine Speeds:

Reduce road speed and follow progressive shifting driving guidelines.

6. Excess Wind Drag:

Decrease cab to trailer gap, add air deflector.

7. Brakes Dragging:

Adjust or repair brakes.

8. Fuel And Combustion Noise (Knock):

Check items listed in PROBLEM NUMBERS 4 and 7.

9. Wrong Fuel Injection Timing:

Make adjustment to timing.

Problem 14: Loud Valve Train Noise

Probable Cause:

1. Damage To Valve Spring(s):

Make replacement of parts with damage.

2. Damage To Camshaft:

Make replacement of parts with damage. Clean engine thoroughly. If replacement of camshaft is made, new valve lifters are also necessary.

3. Damage To Valve Lifter:

Clean engine thoroughly. Make a replacement of the damaged valve lifters. Inspect camshaft cams (lobes) for damage. Look for valves that do not move freely. Make an adjustment to valve clearance according to the Subject, Valve Clearance Setting.

4. Damage To Bridge For Valves Or Bridge Dowel:

Make a replacement of the bridge and/or bridge dowel, and adjust as necessary.

Problem 15: Too Much Valve Lash

Probable Cause:

1. 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 at low rpm. Oil passages must be clean, especially those that send oil to the cylinder head.

2. Rocker Arm Worn At Face That Makes Contact With Bridge:

If there is too much wear, install new parts or rocker arms. Make adjustment of valve clearance according to the Subject, Valve Clearance Setting.

3. Bridge Or Bridge Dowel For Valves Worn:

Make replacement of the bridge and/or bridge dowel, and adjust as necessary.

4. End Of Valve Stem Worn:

If there is too much wear, install new valves. Make adjustment to valve clearance according to the Subject, Valve Clearance Setting.

5. Worn Push Rods:

If there is too much wear, install new push rods. Make adjustment of valve clearance according to the Subject, Valve Clearance Setting.

6. Broken Or Worn Valve Lifters:

Install new valve lifters. Check camshaft for wear. Check for free movement of valves or bent valve stem. Clean engine thoroughly. Make adjustment of valve clearance according to the Subject, Valve Clearance Setting.

7. Worn Cams (Lobes) On Camshaft:

Install a new camshaft. Install new valve lifters if damaged. Check for free movement of valves or bent valve stems. Make adjustment of valve clearance according to the Subject, Valve Clearance Setting.

Problem 16: Valve Rotocoil Or Spring Lock Is Free

Probable Cause:

1. Broken Locks:

Broken locks can cause the valve to get into the cylinder. This will cause much damage.

2. Broken Valve Spring(s):

Install new valve spring(s).

3. Broken Valve:

Replace valve and other damaged parts.

Problem 17: Oil At The Exhaust

Probable Cause:

1. Too Much Oil In The Valve Compartment:

Look at both ends of the rocker arm shaft. Be sure a plug is in each end of the shaft.

2. Worn Valve Guides:

Reconditioning of the cylinder head is needed.

3. Worn Piston Rings:

Inspect and install new parts as needed.

Problem 18: Little Or No Valve Clearance

Probable Cause:

1. Worn Valve Seat Or Face Of Valve:

Reconditioning of cylinder head is needed. Make adjustment of valve clearance according to the Subject, Valve Clearance Setting.

Problem 19: Engine Has Early Wear

Probable Cause:

1. Dirt In Lubrication Oil:

Remove dirty lubrication oil. Install new oil filter elements. Put clean oil in the engine.

2. Air Inlet Leaks:

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

3. Fuel Leakage Into Lubrication Oil:

This will cause high fuel consumption and low engine oil pressure. Make repairs if leaks are found. Install new parts where needed.

Problem 20: Coolant In Lubrication Oil

Probable Cause:

1. Failure Of Engine Oil Cooler Core:

Install a new engine oil cooler. Drain crankcase and refill with clean engine oil. Install new oil filter elements.

2. Failure Of Cylinder Head Gasket Or Water Seals:

Check cylinder liner projection. Install a new spacer plate gasket and new water seals in the spacer plate. Install a new cylinder head gasket. Tighten the bolts that hold the cylinder head according to the Specifications.

3. Crack Or Defect In Cylinder Head:

Install a new cylinder head.

4. Crack Or Defect In Cylinder Block:

Install a new cylinder block.

5. Failure Of Liner Seals:

Replace seals.

6. Crack Or Defect In Cartridge Of Turbocharger:

Install a new turbocharger cartridge.

Problem 21: Too Much Black Or Gray Smoke

Probable Cause:

Engine Runs Smoothly

1. Engine Used In A Lug Condition:

"Lugging" (when the truck is used in a gear too high for engine rpm to go up as accelerator pedal is pushed farther down, or when the truck is used in a gear where engine rpm goes down with accelerator where engine rpm goes down with accelerator pedal at maximum travel) the engine causes a reduction in the intake of air with full fuel delivery to the cylinders. Because there is not enough air to burn all the fuel, the fuel that is not used comes out the exhaust as black smoke. To prevent lugging the engine, use a gear where engine can have "acceleration" (increase in speed) under load.

2. Dirty 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 mamometer or a vacuum gauge (which measures in inches of water). Make a connection to the piping between the air cleaner and the inlet of the turbocharger. Check with the engine running at full load rpm. Maximum restriction is 635 mm (25 in.) of water. If a gauge is not available, visually check the air cleaner element for dirt. If the element is dirty, clean the element or install a new element.

3. 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 pushed too far on the inlet pipe. If no damage is seen, check inlet restriction with a clean air cleaner element.

4. Exhaust System Restriction:

Make a visual inspection of the exhaust system. Check for damage to piping or for a bad muffler. If no damage is found, you can 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. You can also check by removing the exhaust pipes from the exhaust manifolds. With the exhaust pipes removed, start and load the engine on a chassis dynamometer to see if the problem is corrected.

5. Fuel Injection Timing Not Correct:

Check and make necessary adjustments as given in the Testing And Adjusting section of this Service Manual.

6. Fuel Setting Is Not Correct:

Check and make necessary adjustments as per Testing And Adjusting Section of this Service Manual. See the Rack Setting Information for the correct fuel setting.

7. Low Quality Fuel:

Remove the fuel from the fuel tank. Install a new fuel filter element. Put a good grade of clean fuel in the fuel tank. See Fuels For Caterpillar Diesel Engines, Special Instruction, Form No. SEHS7067 and Measuring Diesel Fuel AP1 Specific Gravity, Special Instruction, Form No. GMG00977.

8. Valve Adjustment Not Correct Or Valve Leakage:

Check and make necessary adjustments as per Testing And Adjusting section of this Service Manual. Intake valve clearance is 0.38 mm (.015 in.) and exhaust valve clearance is 0.76 mm (.030 in.). Valve leakage normally causes the engine to "misfire" (injection not regular) and run rough.

9. Bad Fuel Nozzle(s):

Bad fuel nozzles will normally cause the engine to "misfire" (injection not regular) and run rough, but can cause too much smoke with engine still running smooth. Remove the fuel nozzles and test as given in the Testing And Adjusting of this Service Manual.

10. Defect In Fuel Ratio Control:

Make adjustment to or install new control.

Engine Runs Rough

11. Misfiring Cylinder(s):

See Engine Misfires Or Runs Rough.

12. Fuel Injection Timing Not Correct:

Check and make necessary adjustments as per Testing And Adjusting section of this Service Manual.

13. Automatic Timing Advance Does Not Operate Correctly:

Check with engine warm. Use the 8T5300 Engine Timing Indicator Group. Special Instruction Form No. SEHS8580 has instructions and calibration for this tool group. If the timing indicator group is not available, make a rapid "acceleration" (increase in speed) from low idle to high idle. Engine must have smooth acceleration. A timing advance that does not operate correctly can cause delays of the engine acceleration at some rpm before high idle, or possibly cause the engine to run rough and have exhaust noise (backfire) during acceleration. This condition is difficult to find if engine acceleration is slow or at a constant engine rpm.

14. 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. If the engine will not start, loosen a fuel injection line nut at the valve cover base. With the governor lever in the shutoff position, crank the engine until the flow of fuel from the loosened fuel injection line is free of air. Tighten the fuel line nut. If the engine still does not run smooth or releases a large amount of white smoke, loosen the fuel line nuts one at a time at the valve cover base until the fuel that comes out is free of air. Tighten the fuel line nuts. If the air cannot be removed in this way, put 35 kPa (5 psi) of air pressure to the fuel tank.

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NOTICE

Do not use more than 55 kPa (8 psi) of air pressure in the fuel tank or damage to the tank may result.

Problem 22: Too Much White Or Blue Smoke

Probable Cause:

White Smoke

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.

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:

4. Air In Fuel System:

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NOTICE

Do not use more than 55 kPa (8 psi) of air pressure in the fuel tank or damage to the tank may result.

5. Fuel Injection Timing Not Correct:

Check and make necessary adjustments as given in the Testing And Adjusting section of this Service Manual.

13. Automatic Timing Advance Does Not Operate Correctly:

7. Valve Adjustment Not Correct:

8. Bad Fuel Nozzle(s):

Bad fuel nozzles will normally cause the engine to "misfire" (injection not regular) and run rough, but can cause too much smoke and the engine still be running smooth. Remove the fuel nozzles and test as given in the Testing And Adjusting section of this Service Manual.

9. Misfiring Cylinder(s):

See Engine Misfires Or Runs Rough.

Blue Smoke

10. Engine Oil Level 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 crankcase. See Fuel In Crankcase Oil.

11. Worn Valve Guides:

See the Specifications section of this Service Manual for the maximum permissible wear of the valve guides.

12. 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. Make a visual inspection of the cylinder walls and piston rings. If necessary, measure the cylinder walls and piston rings. For the cylinder and piston ring specifications, see the Specifications section of this Service Manual.

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

13. Wear Or Damage To Pistons:

Check the piston ring grooves of wear. This engine has piston grooves and rings of the Keystone (taper) design. A special 8T3150 Keystone Piston Ring Groove Gauge is available to check the top two ring grooves in the piston. For instruction on use of the gauge group, see the instruction card that is with the gauge group. 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.

14. Failure Of Turbocharger Oil Seal:

Check inlet manifold for oil. Replace seals and repair turbocharger if necessary.

15. Coolant In Combustion System:

Check for cracked head.

Problem 23: Engine Has Low Oil Pressure

Probable Cause:

1. Dirty Oil Filter Or Oil Cooler:

Check the operation of bypass valve for the filter. Install new oil filter elements if needed. Clean or install new oil cooler core. Remove dirty oil from engine. Put clean oil in engine.

2. Diesel Fuel In Lubrication Oil:

Find the place where diesel fuel gets into the lubrication oil. Make repairs as needed. Remove the lubrication oil that has diesel fuel in it. Install new oil filter elements. Put clean oil in the engine.

3. Too Much Clearance Between Rocker Arm Shaft And Rocker Arms:

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

4. Oil Pump Suction Pipe Has A Defect:

Replacement of pipe is necessary.

5. Relief Valve For Oil Pump Does Not Operate Correctly:

Clean valve and housing. Install new parts as necessary.

6. Oil Pump Is Worn Or Has A Defect:

Repair or make replacement of necessary parts.

7. Too Much Clearance Between Crankshaft And Crankshaft Bearings:

Inspect crankshaft and bearings. Install new parts as necessary.

8. Too Much Clearance Between Camshaft And Camshaft Bearings:

Install new camshaft bearings. Install new camshaft if necessary.

9. Defect In Oil Pressure Gauge:

Install new gauge.

10. Too Much Bearing Clearance For Idler Gear:

Inspect bearings and make replacement as necessary.

Problem 24: Engine Uses Too Much Lubrication Oil

Probable Cause:

1. Too Much Lubrication Oil In 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 necessary.

3. Oil Temperature Is Too High:

Check operation of engine oil cooler. Clean the core of the engine oil cooler. Install new parts if necessary.

4. Too Much Oil In The Valve Compartment:

Look at both ends of the rocker arm shaft. Be sure a plug is in each end of the shaft.

5. Worn Valve Guides:

Reconditioning of the cylinder head is necessary.

6. Worn Piston Rings And Cylinders:

Inspect and install new parts as necessary. Reconditioning of the cylinder block may be necessary.

7. Failure Of Seal Rings In Turbocharger:

Check inlet manifold for oil and make repair to turbocharger if necessary.

Problem 25: Fuel In Crankcase Oil

Probable Cause:

1. Loose Inner Fuel Injection Line Nut(s):

A loose fuel injection line nut or a bad O-ring seal on the end of the adapter inside the valve cover base can cause fuel leakage into the crankcase. Check for a bad O-ring seal and tighten nuts to 40 ± 7 N·m (30 ± 5 lb.ft.).

2. Fuel Nozzle Leaks:

Remove fuel nozzles and check the tips for indications of wire brushing. Wire brushing can change the performance of the nozzles. Test the nozzles, see the procedure given in the Testing And Adjusting section.

On 7000 Series Nozzles a loose bleed screw or leaking bleed screw washer will cause fuel dilution in the crankcase. Check for bad bleed screw washers or damaged bleed screw washer face. Make sure the bleed screws are tightened to 2.2 ± 0.8 N·m (20 ± 7 lb.in.).

NOTE: Any time the bleed screws are loosened or removed the washer (seal) must be replaced to help prevent leakage.

Problem 26: Engine Coolant Is Too Hot

Probable Cause:

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 through the radiator to release the heat into the cooling air. Low coolant level is caused by leaks or wrong filling of the radiator. With the engine cool, be sure the coolant can be seen at the low end of the fill neck on the radiator top tank.

2. Bad 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 you know is good or check the cooling system with the 8T470 Thermistor Thermometer Group.

3. Dirty Radiator:

Check the radiator 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 prevents free flow of coolant through the radiator.

4. Loose Belt(s):

Loose fan or water pump belts will cause a reduction in air or water flow. Tighten the belts according to V-BELT TENSION CHART that is shown in Specification section.

5. Bad Hose(s):

Bad 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 50,000 miles or a year of use. The inside can become loose, and the loose particles of the hose can cause a restriction in the flow of coolant.

6. Shunt Line Restriction:

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

7. Shutters Not Opening Correctly:

Check the opening temperature of the shutters. The shutters must be completely closed at a temperature below the fully open temperature of the water temperature regulators. Also, verify that fan control switches or viscous fans are operating correctly.

8. Bad Water Temperature Regulator (Thermosat):

A regulator that does not open, or only opens part of the way, can cause above normal heating. See the Testing and Adjusting section for the procedure to test water temperature regulators.

9. Bad Water Pump:

A water pump with a loose impeller does not pump enough coolant for correct engine cooling. A loose impeller can be found by removing the water pump, and by pushing the shaft back and pulling it forward. If the impeller has no damage, check the impeller clearance. The clearance between the impeller and the housing is 0.56 to 1.50 mm (.022 to .059 in.).

10. Air In Cooling System:

Air can get into the cooling system in different ways. The most common causes are not filling the cooling system correctly, and combustion gas leaking into the system. Combustion gas can get into the system through inside cracks or bad cylinder head gaskets. Air in the cooling system causes a reduction in coolant flow and bubbles in the coolant. Air bubbles hold coolant away from engine parts, preventing heat flow.

Air in the cooling system can be found by the BOTTLE TEST. The equipment needed to make this test is a one pint bottle, a bucket of water, and a hose which will fit the end of the overflow pipe of the radiator.

Before testing make sure the cooling system is filled correctly. Use a wire to hold the relief valve in the radiator cap open. Install the radiator cap and tighten it. Put the hose over the end of the overflow pipe.

Start the engine and operate it at high idle rpm for a minimum of five minutes after the engine is at normal operating temperature. Use a cover on the radiator core to keep the engine at operating temperature. After five or more minutes at operating temperature, place the loose end of the hose in the bottle filled with water. Put the bottle in the bucket of water with the top down. If the water gets out of the bottle in less than forty seconds, there is too much exhaust gas leakage into the cooling system. Find the cause of the air or gas getting into the cooling system and correct as necessary.

11. Wrong Fan, Fan Or Shroud Not In Correct Position:

A wrong 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. Make sure the fan size, fan shroud, and position of fan and shroud are according to the recommendations of the Truck Manufacturer.

12. Radiator Too Small:

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 higher than normal temperatures. Make sure the radiator size is according to the recommendations of the Truck Manufacturer.

13. Not Enough Air Flow Through Radiator Because Of Restriction In 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.

14. High 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. To get better cooling, use the truck in a lower gear.

15. Operating At High Altitude:

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

16. Engine Used In A Lug Condition:

"Lugging" (when the truck is used in a gear too high for engine rpm to go up as accelerator pedal is pushed farther down, or when the truck is used in a gear where engine rpm goes down with accelerator pedal at maximum travel) the engine causes the engine rpm and fan rpm to be low. 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.

17. Air Inlet Restriction:

Restriction of the air coming into the engine causes high cylinder temperatures and more than normal amount of heat to pass to the cooling system. Check for a 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 gauge installed, run engine at full load rpm and check the restriction. Maximum restriction of air inlet 635 mm (25 inches) of water. If the indication is higher than the maximum permissible restriction, remove the dirt from the filter element, or install a new filter element and check the restriction again. If the indication is still too high, there must be a restriction in the inlet piping.

18. Exhaust Restriction:

Restriction in the exhaust system causes high cylinder temperatures and more than normal amount of heat to pass to the cooling system. To see if there is an exhaust restriction, make a visual inspection of the exhaust system. Check for damage to piping or for a bad muffler. If no damage is found, check the system for 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. You can also 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.

19. Fuel Injection Timing Not Correct:

Check and make necessary adjustments as given in the Testing and Adjusting section.

20. Transmission Problems:

Power-shift or automatic transmissions that are cooled by the engine cooling system can cause above normal heating if they are out of adjustment or not working correctly. See the transmission Service Manual for the correct adjustments.

Problem 27: Engine Does Not Run Hot Enough

Probable Cause:

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, and a very slow speed or downhill travel can cause overcooling because of the low heat input of the engine. The installation of shutters helps to correct this condition.

3. Bad Water Temperature Regulators (Thermostats):

A regulator that is "stuck" open (will not move to the closed position) will cause overcooling. A thermostat that is stuck between the open and closed positions, or only opens part of the way, can cause overcooling when the truck has a light load. Also, coolant leaks around the thermostat, such as vent lines, can cause overcooling.

Problem 28: Exhaust Temperature Is Too High

Probable Cause:

1. Air Inlet Or Exhaust System Has A Restriction:

Remove restriction.

2. Wrong Fuel Injection Timing:

Make an adjustment to the timing.

Problem 29: Starter Motor Does Not Turn

Probable Cause:

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. Starter Motor Solenoid Has A Defect:

Install a new solenoid.

4. Starter Motor Has A Defect:

Make repair or replacement of starter motor.

Problem 30: Alternator Gives No Charge

Probable Cause:

1. Loose 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 parts with defect.

3. Rotor (Field Coil) Has A Defect:

Install a new rotor.

Problem 31: Alternator Charge Rate Is Low Or Not Regular

Probable Cause:

1. Loose 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 parts with defect.

3. Alternator Regulator Has A Defect:

Install a new alternator regulator.

4. Alternator Regulator Not Adjusted Correctly:

See Electrical System in Testing and Adjusting. Some alternator regulators can be adjusted and some can not be adjusted.

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 32: Alternator Charge Rate Is Too High

Probable Cause:

1. Alternator Or Alternator Regulator Has Loose Connections:

Tighten all connections to alternator or alternator regulator.

2. Alternator Regulator Has A Defect:

Install a new alternator regulator.

Problem 33: Alternator Has Noise

Probable Cause:

1. Drive Belt For Alternator Is Worn Or Has A Defect:

Install a new drive belt for the alternator.

2. Loose Alternator Drive Pulley:

Check groove in pulley for key that holds pulley in place. If groove is worn, install a new pulley. Tighten pulley nut according to Specifications.

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.

5. Rotor Shaft Is Bent:

Make a replacement of the rotor shaft.

6. Rectifiers In The Alternator Are Shorted:

Make a replacement of the diode assembly.

Problem 34: Problem With Vehicle Or Vehicle Operation

Probable Cause:

1. Tachometer Error:

To check, connect a tachometer of known accuracy to the engine. Run the engine and make a comparison of the readings of the vehicle and test tachometers. If vehicle tachometer is bad, make repairs as necessary or install a new tachometer.

2. Engine Operated At High Altitude:

Less oxygen at higher altitudes causes the engine horsepower to go down. There is no effect on the horsepower of the engine for the first 2280 m (7500 ft) above sea level of operation.

3. Brakes Do Not Completely Release:

Check the brakes by feeling all the brake drums. If the brakes of a wheel do not completely release, the brake drum for that wheel will be hotter than the brake drums for the other wheels. With the truck lifted with a jack, the wheels must have free rotation when turned by hand.

4. Vehicle Operated In Too High A Gear:

If the operator does not shift the truck correctly, or operates the truck in a "lug" condition (using the truck in too high a gear for engine rpm to go up as accelerator pedal is pushed farther down, or using the truck in a gear where engine rpm goes down with accelerator pedal at maximum travel), poor vehicle performance is the result.

5. Extra Engine Driven Equipment:

Air compressors, hydraulic pumps, alternator, and other engine driven equipment that has damage, or that was not installed correctly, or that is not in correct adjustment, can take more horsepower to drive than expected. If necessary, disconnect the equipment and test the engine.

6. Speedometer Error:

A bad speedometer does not give the correct speed or the correct indication of fuel consumption. An indication of low speed can cause the operator to feel that he has a power problem.

7. Speeds Too High:

The need for more horsepower is easy to see as the speed of the vehicle is increased. This is especially true if the front of the vehicle has a large surface area. Application personnel can give you the horsepower necessary for different vehicle designs at different speeds.

8. Overload On Vehicle:

Application personnel can give you the horsepower needs for different vehicles.

9. High Moving Resistance:

Soft ground conditions cause a need for more horsepower. To see if the problem is the engine, test the vehicle on a surface known to be good, or test on a chassis dynamometer.

10. High Wind Resistance:

The horsepower needs for a truck can be divided into two parts. Part of the horsepower is used to move the vehicle and part is used to get through the resistance of the wind. The horsepower necessary to get through the resistance of the wind will increase as the vehicle is used at higher speeds. Vehicles with large front area have a higher wind resistance and take more horsepower than those with a small front area. Some types of trucks, for example those used for the transportation of automobiles and/or boats have high wind resistance even if the front area is small. Moving against the wind has the same effect on wind resistance as does higher vehicle speed.

11. Power Loss In Drive Gears:

It is possible for a transmission or rear axle to use extra horsepower because of damage, not being in correct adjustment, having the wrong type of fluid or not enough fluid in them, or an inside mechanical problem. If a part of the drive train unit operates at a higher temperature than normal, it can be the problem. Check this part of the drive train unit before working on any other part of the drive train unit. Powershift or automatic transmissions can cause the vehicle performance to be low if they are out of adjustment or not working correctly. See the transmission Service Manual for the correct adjustments.

12. Wrong Gear Ratios:

The tire size, rear axle ratio, and transmission gear ratios must be correct to get maximum engine performance. If the transmission gear ratios are wrong, they can cause the engine rpm to go low enough during shifting that the engine cannot have correct "acceleration" (increase in speed). A rear axle gear ratio which supplies too high a vehicle speed with the engine at a low rpm during normal vehicle operation, will cause the engine to be "lugging" (when the truck is used in a gear too high for engine rpm to go up as accelerator pedal is pushed farther down, or when the truck is used in a gear where engine rpm goes down with accelerator pedal at maximum travel). Application personnel can give you the correct tire sizes and gear ratios for your operation.

13. Chassis Dynamometer Error:

Chassis dynamometers can be a great help in testing a vehicle for engine performance if they are in good condition and used correctly. When the dynamometer is not in good condition, or a bad operating procedure is used, the result will be wrong readings. For good comparison of horsepower readings from different vehicles, use the same dynamometer with the same operator.

14. Trailers That Are Difficult To Pull:

Some trailers are more difficult to pull than others because of several factors. Some of these factors are: brakes not released completely, high wind resistance (because of a large front area and/or the design of the trailer), axles not in alignment, extra axles, and low tire pressure.

15. High Inlet Air Temperature:

Air coming into the engine must be cool for the engine to have full horsepower. If the air inlet system is not of correct design or is not in good mechanical condition, hot air can come into the engine causing a loss of horsepower. To check the inlet air temperature, install the 9S9102 Thermistor Thermometer Group into the engine air inlet pipe.