Introduction

Reference: For Specifications with illustrations, make reference to Specifications for G3408 & G3412 Engines, SENR6407. If the Specifications in SENR6407 are not the same as in the Systems Operation and the Testing and Adjusting, look at the printing date on the front 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.

1. Engine Will Not Turn When Start Switch Is On.

2. Engine Will Not Start.

3. Misfiring Or Running Rough.

4. Stall At Low rpm.

5. Sudden Changes In Engine Speed (rpm).

6. Not Enough Power.

7. Too Much Vibration.

8. Loud Combustion Noise.

9. Loud Noise (Clicking) From Valve Compartment.

10. Oil In Cooling System.

11. Mechanical Noise (Knock) In Engine.

12. Gas Consumption Too High.

13. Loud Noise From Valves Or Valve Drive Components.

14. Little Movement Of Rocker Arm And Too Much Valve Lash.

15. Valve Rotocoil Or Spring Lock Is Free.

16. Oil At The Exhaust.

17. Little Or No Valve Lash.

18. Engine Has Early Wear.

19. Coolant In Lubrication Oil.

20. Exhaust Temperature Is Too High.

21. Engine Has Low Oil Pressure.

22. Engine Uses Too Much Lubrication Oil.

23. Engine Coolant Is Too Hot.

24. Starter Motor Does Not Turn.

25. Alternator Gives No Charge.

26. Alternator Charge Rate Is Low Or Not Regular.

27. Alternator Charge Too High.

28. Alternator Has Noise.

29. Short Spark Plug Life.

30. Pre-Ignition.

31. Detonation.

32. Gas Supply Line Shutoff Valve Failure.

33. Failure Of Overspeed Contactor Switch To Shutoff Engine.

34. Overspeed Contactor Stops Engine At Low Speed.

35. Solid State Magneto (Altronic).

36. Contactor Switch (Water Temperature) Fails to Signal Shutoff.

37. Contactor Switch (Water Temperature) Signals Shutoff at Low Temperature.

38. Oil Pressure Contactor Fails to Signal Shutoff.

39. Overspeed Contactor Switch Fails to Signal Shutoff.

40. Overspeed Contactor Switch Signals Shutoff at Low Speed.

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

Probable Cause:

1. Battery Has Low Output:

Make reference to Problem 24.

2. Wiring Or Switches Have Defect:

Make reference to Problem 24.

3. Starter Motor Solenoid Has A Defect:

Make reference to Problem 24.

4. Starter Motor Has A Defect:

Make reference to Problem 24.

5. Inside Problem Prevents Engine Crankshaft From Turning:

If the crankshaft cannot be turned after disconnecting the driven equipment, remove the spark plugs and check for fluid in the cylinders. 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, piston seizure, wrong pistons installed in the engine, and valves making contact with pistons.

Problem 2: Engine Will Not Start

Probable Cause:

1. No Gas To Engine:

Check gas supply and pressure regulator. Reset shutoff valve in the supply line. Check carburetor throttle, and linkage between carburetor and governor.

2. Wrong Ignition:

Time magneto to engine.

3. Timing Failure:

Check the ignition transformers for loose connection, moisture, short or open circuits. Check the low and high tension wiring. Check the spark plugs for correct type and spark plug adapters. Check the magneto. Repair or replace any component that shows signs of failure.

4. Carburetor Not Working:

Check all carburetor adjustments. Be sure that throttle plate is open and that governor permits it to open fully. Check the BTU content of the fuel based on lower heat value (LHV). If it is too low, a higher fuel pressure (correct spring force in the regulator), or a special carburetor may be needed. Inspect the fuel-air diaphragm for leaks, dirt or wet fuel. Check the governor high idle and carburetor stop screw for low idle adjustments.

5. Slow Cranking Speed:

Cranking speed must be at least 150 rpm. Check condition of starting system. See Problem 24.

6. Engine protection system is grounding magneto output.

Engine stop-bypass switch must be activated during engine startup until oil pressure is achieved.

Problem 3: Misfiring Or Running Rough

Probable Cause:

1. Ignition Failure:

Make reference to Problem 2.

2. Low Gas Pressure:

Check for leaks in gas supply. Check the line pressure regulator, shutoff valve and solenoid. If two or more engines are used, be sure the common supply line is large enough. Regulator pressure should not change over the normal load range. Inspect the regulator diaphragm for leaks and valve for correct seat contact. Check gas pressure before and after the line pressure regulator. Check for restriction in balance line from carburetor to regulator. Set valve lash.

Problem 4: Stalls At Low RPM

Probable Cause:

1. Idle RPM Too Low:

Make adjustment to the throttle stop screw at the carburetor.

2. Too Much Load:

Check for attachment excessive loading. Reduce load and/or adjust throttle stop. If necessary, disconnect attachments and test engine.

Problem 5: Sudden Changes In Engine Speed (RPM)

Probable Cause:

1. Governor Failure:

Look for damaged or broken springs, linkage or other components. Check governor-to-carburetor linkage or other components. Check for correct spring. Check governor oil pump and bypass valve.

2. Wrong Adjustment Or Leaky Valve:

Make adjustment to the valves.

3. Turbocharger Differential Pressure Control Valve Failure:

Inspect the valve. Check valve diaphragm and boost air hose for leakage. Check breather element for plugging.

4. Governor Or Linkage Adjustment Incorrect:

Check to see if linkage between governor and carburetor operates smoothly and has no free play. Make adjustment to the governor and linkage as necessary.

Problem 6: Not Enough Power

Probable Cause:

1. Low Gas Pressure Or Gas Line Pressure Regulator Failure:

Clean balance line. Check inlet and outlet regulator pressures.

2. Carburetor Adjustment Or Carburetor Not Working:

Make reference to Problem 2.

3. Leaks In Air Induction System:

Check air cleaner for restriction. Check inlet manifold pressure on turbocharger engines.

4. Governor Control Linkage And/Or Throttle Valve Balance (Synchronized):

Adjust linkage and make adjustment to throttle valve balance (synchronize).

5. Too Much Valve Lash:

Make adjustments according to the subject Valve Lash.

6. Ignition Wiring Failure:

Check for damage to wiring, arcing, or bare wire.

Check rubber boot over spark plugs for cracks or moisture.

7. Transformer Failure:

Check for loose connections, moisture, short or open circuits.

8. Bad Spark Plugs:

Check type of plug used. Install correct type. Inspect for gas leaks and/or cracked porcelain. Clean and set gap of the plugs. Install new plugs if badly worn.

9. Wrong Timing:

Time magneto to engine. Tighten any loose wires.

10. Spark Plug Adapters Leak:

Check for water leakage into cylinder, or combustion gases in coolant. Install new adapters.

11. Differential Pressure Regulator Failure:

Check the valve movement. Check the diaphragm and boost air hose for leaks. Check breather element for plugging.

12. Too Much Carbon In Turbocharger Or Slow Turning:

Inspect and install a new turbocharger as necessary.

13. Deposits In The Combustion Chamber:

Make a compression test on all cylinders. Any cylinder which has great difference from the others should be inspected and cleaned.

Problem 7: Too Much Vibration

Probable Cause:

1. Loose Bolts Or Nuts Holding Pulley Or Damper:

Tighten bolts or nuts.

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 mounting bolts. Install new components if necessary.

4. Misfiring Or Running Rough:

Make reference to Problem 3.

Problem 8: Loud Combustion Noise (Sound)

Probable Cause:

1. Gas Octane Rating Too Low:

Use recommended gas.

2. Detonation:

Make reference to Problem 31.

3. Pre-Ignition:

Make reference to Problem 30.

Problem 9: Loud Noise (Clicking) From Valve Compartment

Probable Cause:

1. Broken Valve Spring(s) Or Locks:

Install new parts where necessary. Broken locks can cause the valve to slide 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 sending oil to the cylinder head.

3. Not Enough Valve Lash:

Make adjustments according to the subject Valve Lash.

Problem 10. Oil In Cooling System

Probable Cause:

1. Defect In Core Of Oil Cooler:

Install a new core in the oil cooler.

2. Defect In Head Gasket.

Install a new head gasket.

Problem 11: Mechanical Noise (Knock) In Engine

Probable Cause:

1. Failure Of Bearing For Connecting Rod:

Inspect the bearing for the connection rod and the bearing surface on the crankshaft. Install new parts where necessary.

2. Damaged Timing Gears:

Install new parts where necessary.

3. Defect In Attachment:

Repair or install new components.

4. Broken Crankshaft:

Install a new crankshaft.

Problem 12: Gas Consumption Too High

Probable Cause:

1. Gas System Leaks:

Replacement of parts is needed at points of leakage.

2. Spark Plugs Not Firing:

Check and install new plugs if necessary.

3. Wrong Timing:

Make adjustment to timing.

Problem 13: Loud Noise From Valves Or Valve Drive Components

Probable Cause:

1. Broken Valve Spring(s):

Make replacement of damaged parts.

2. Broken Camshaft:

Make replacement of damaged parts. Clean engine thoroughly.

3. Vibration Damper Has Defect:

Install a new damper.

Problem 14: Little Movement Of Rocker Arm And 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 sending oil to the cylinder head.

2. Rocker Arm Worn At Face That Contacts End Of Valve:

If there is too much wear, install new rocker arms. Make adjustment of valve lash according to the subject Valve Lash.

3. End Of Valve Stem Worn:

If there is too much wear, install new valves. Make adjustment of valve lash according to the subject Valve Lash.

4. Worn Push Rods.

If there is too much wear, install new push rods. Make adjustment of valve lash according to the subject Valve Lash.

5. Valve Lifters Worn:

If there is too much wear, install new valve lifters. Make adjustment of valve lash according to the subject Valve Lash.

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 lash according to the subject Valve Lash.

7. Worn Cams On Camshaft:

Check valve lash. Check for free movement of valves or bent valve stems. Install a new camshaft. Make adjustment of valve lash according to the subject Valve Lash.

Problem 15: Valve Rotocoil Or Spring Lock Is Free

Probable Cause:

1. Broken Locks:

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

2. Broken valve spring(s).

Install new valve spring(s).

Problem 16. 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 that there is a plug in each end.

2. Worn Valve Guides:

Reconditioning of the cylinder head is needed.

3. Worn Piston Rings:

Inspect and install new parts as needed.

4. Turbocharger Leak:

Check turbocharger oil seals.

Problem 17: Little Or No Valve Lash

Probable Cause:

1. Worn Valve Seat Or Face Of Valve:

Reconditioning of cylinder head is needed. Make adjustment of valve lash according to the subject Valve Lash.

Problem 18: Engine Has Early Wear

Probable Cause:

1. Dirt In Lubrication Oil:

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

2. Air Inlet Leaks:

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

3. Incorrect Lubricating Oil Or Oil Change Periods For Application:

Determine correct lubricating oil and oil change periods for type of application. Refer to Lubrication Section of Operation And Maintenance Guide, and Application And Installation Guide, LEBH6154.

Problem 19. Coolant In Lubrication Oil

Probable Cause:

1. Failure Of Oil Cooler Core:

Install a new core for the oil cooler.

2. Failure Of Cylinder Head Gasket:

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 spark plug adapter seal between adapter and cylinder head:

Install a new seal.

Problem 20: Exhaust Temperature Is Too High

Probable Cause:

1. Air Inlet System Has A Leak:

Check pressure in the air inlet manifold. Look for restrictions at the air cleaner. 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:

Remove restriction.

4. Wrong Timing:

Make an adjustment to the timing.

5. Change in fuel BTU:

Adjust the air/fuel ratio to the new BTU.

Problem 21: Engine Has Low Oil Pressure

Probable Cause:

1. Dirty Oil Filter Or Oil Cooler:

Check the operation of bypass valve. 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. Too Much Clearance Between Rocker Arm Shaft And Rocker Arms:

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

3. Oil Pump Suction Pipe Has A Defect:

Replacement of pipe is needed.

4. Oil Pump pressure Regulating Valve Does Not Close:

Clean valve and housing. Install new parts as necessary.

5. Oil Pump Has A Defect:

Repair or replace oil pump as necessary.

6. Too Much Clearance Between Crankshaft And Crankshaft Bearings:

Install new crankshaft bearings.

7. Too Much Clearance Between Camshaft And Camshaft Bearings:

Install new camshaft and camshaft bearings if necessary.

8. Defect In Oil Pressure Gauge:

Install new gauge.

9. Broken piston cooling jet:

Install new jet.

Problem 22: Engine Uses Too Much Lubrication Oil

Probable Cause:

1. Too Much Lubricating Oil In Engine:

Remove extra oil. Find where extra oil comes from. Put correct amount of oil in engine. Do not put too much oil in engine.

2. Oil Leaks:

Find all oil leaks. Make repairs as needed.

3. Oil Temperature Is Too High:

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

4. Too Much Oil In Valve Compartment:

Make reference to Problem 16.

5. Worn Valve Guides:

Make reference to Problem 16.

6. Worn Piston Rings:

Install new parts if necessary.

7. Plugged Crankcase Breather:

Clean breather.

Problem 23: Engine Coolant Is Too Hot

Probable Cause:

1. Restriction To Air Flow Through Radiator Or Restriction To Flow Of Coolant Through The Heat Exchanger:

Remove all restrictions of flow.

2. Not Enough Coolant In System:

Add coolant to cooling system.

3. Pressure Cap Has A Defect:

Check operation of pressure cap. Install a new pressure cap if necessary.

4. Combustion Gases In Coolant:

Find out where gases get into the cooling system. Make repairs as needed.

5. Water Temperature Regulators (Thermostats) Or Temperature Gauge Has A Defect:

Check water temperature regulators for correct operation. Check temperature gauge operation. Install new parts as necessary.

6. Water Pump Has A Defect:

Install a new water pump.

7. Too Much Load On The System:

Reduce the load.

8. Wrong Timing:

Make adjustment to timing.

9. Change In Fuel BTU:

Adjust the timing to the new BTU.

Problem 24: Starter Motor Does Not Turn

Probable Cause:

1. Battery Has Low Output:

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

2. Wiring 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.

5. Inside Of Engine Problem:

Make reference to Problem 1.

Problem 25: 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 defective parts.

3. Brushes Have A Defect:

Install new brushes.

4. Rotor (Field Coil) Has A Defect:

Install a new rotor.

Problem 26: 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 defective parts.

3. Alternator Regulator Has A Defect:

Make an adjustment or replacement of 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:

1. Alternator Or Alternator Regulator Has Loose Connections:

Tighten all connections to alternator or alternator regulator.

2. Alternator Regulator Has A Defect:

Make an adjustment or replacement of alternator regulator.

Problem 28: 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 key groove in pulley for wear. 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.

Problem 29: Short Spark Plug Life

Probable Cause:

1. Wrong Polarity Of Connections At Transformers:

Check wiring diagrams in Systems Operation. Make change to the connection of wires to the primary coil of transformers.

2. Wrong Magneto Timing (Ignition Sequence):

Time magneto to engine.

3. Wrong Spark Plugs:

Install correct spark plugs.

4. Incorrect Spark Plug Gap:

Clean and make adjustment to the plug gap.

Problem 30: Pre-Ignition

Probable Cause:

1. Worn Spark Plugs:

Clean and make adjustment to the plug gap. If worn install new plugs.

2. Water Leakage In Cylinder Or Combustion Gas In Coolant:

Inspect spark plug adapter gasket. Check spotface for adapter in head for roughness. Install a new adapter to correct torque with the engine COLD.

Problem 31: Detonation

Probable Cause:

1. Wrong Magneto Timing:

Make Adjustment to magneto timing.

2. Deposits In Combustion Chamber:

Remove deposits from combustion chambers.

3. High Ambient Air Temperature:

Check for high engine room temperature or high temperature of water to aftercooler. Check that air has been vented from aftercooler water.

4. Overload.

Reduce the load.

5. Obstructions In Aftercooler:

Inspect, clean or install new aftercooler as necessary.

6. Change In Fuel BTU:

Adjust the timing to the new BTU.

Problem 32: Gas Supply Line Shutoff Valve Failure

Probable Cause:

1. Defect In Solenoid:

Install new solenoid.

2. Wrong Electrical Rated Solenoid:

Install new solenoid with correct electrical rating.

3. Defect In Wiring And/Or Connections:

Correct the defect in wiring and connections.

Problem 33: Failure Of Overspeed Contactor Switch To Shutoff Engine

Probable Cause:

1. Wrong Electrical Connections:

Check connection, wiring and correct where necessary.

2. Wrong Adjustment:

Make adjustment or install new contactor switch.

Problem 34: Overspeed Contactor Stops Engine At Low Speed

Probable Cause:

1. Wrong Adjustment:

Make adjustment or install new contactor switch if necessary.

Problem 35: Solid State Magneto

Probable Cause:

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NOTICE
Both the high tension lead at the spark plug and the internal seal between spark plug adapter and valve cover must be installed on all cylinders when running the engine. Failure to do this may allow a spark from the exposed lead to ignite crankcase vapors. Engine damage could result.

1. Missing On One Or More Cylinders:

a. Use a 1P1790 Firing Indicator to find which cylinder(s) is missing.

NOTE: The brightness of the neon bulb used in this tool indicates the required voltage of the spark plug only. It does not reflect the output of the magneto.

b. Find where wire, in the primary magneto harness, (wire from magneto to transformer), is connected to the problem cylinder. See Wiring Diagrams in Systems Operation.

c. Stop the engine and disconnect the magneto harness connector from the magneto.

NOTE: All ohmmeters must be "zeroed" (adjusted to read zero when the leads are connected together) before using. Follow instructions with your meter.

All meters have a percentage of error because of the type of meter movement used. This error can be from three to five percent. A variation between meters is normal.

d. Using an ohmmeter having a scale of RX1, connect the probes between the pin of the problem cylinder, (pin in wiring harness), and a good ground. Read the resistance. The resistance should be between .1 and .2 ohms. If reading is within specification the primary circuit is not defective. Proceed to Step g.

A reading of less than .1 ohm indicates grounded primary wire or shorted primary in the transformer. A reading of more than .2 ohms indicates poor connections, defective primary in transformer, or poor ground connection.

e. To locate the defect, disconnect the primary wire from the transformer, (wire from magneto). Connect the ohmmeter to the primary stud of the transformer and ground. Check resistance again. Correct reading is .1 to .2 ohms.

Correct reading: defect in primary harness wire or connector in harness.

Incorrect reading: defective transformer or poor ground.

f. Connect the ohmmeter across the primary terminals of the transformer. Read the resistance. Correct reading is .1 to .2 ohms.

Correct reading: poor ground.

Incorrect reading: defective transformer.

9. With the magneto harness still disconnected, remove the spark plug high tension lead from the spark plug. Do not remove the transformer.

h. Using a scale of RX100 or RX1000, connect the ohmmeter between the spark plug connector and ground. The resistance should be between 5,000 to 8,000 ohms.

Correct reading: defective spark plug or magneto.

Incorrect reading: defective spark plug high tension lead, transformer or ground.

i. Remove the spark plug high tension lead from the transformer. Read resistance between high tension outlet of the transformer to ground. The resistance should be between 5,000 to 8,000 ohms.

Correct reading: defective spark plug high tension lead and/or connections.

Incorrect reading: defective transformer or ground.

j. Connect ohmmeter between the high tension outlet of the transformer and ground terminal of the transformer. The correct reading is 5,000 to 8,000 ohms.

Correct reading: defective ground.

Incorrect reading: defective transformer.

2. Engine Dead And Has No Spark:

a. Disconnect the "G" wire from the shutdown circuit. Try to start the engine.

Engine Starts: Defect in shutdown circuit. Repair as required.

Engine Does Not Start: Proceed to Step b.

b. Connect an ohmmeter between the "G" wire and ground.

An ohmmeter reading of infinite (500,000 ohms or greater).

1. The wire is not grounded.

2. Possible defective magneto.

A resistance indication on the ohmmeter.

1. Grounded "G" wire.

2. Defective magneto.

c. Remove the wiring harness connector from the magneto. Connect an ohmmeter between the G pin in the wiring harness connector and ground.

1. Any resistance indication means that the wire is grounded. Replace or repair as required.

2. A reading of infinite indicates that the wire is not grounded. Defective magneto. Repair or replace the magneto.

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NOTICE
Be sure to reconnect the wire to the magnetic switch and the connector to the magneto after the repairs are made.

Problem 36. Contactor Switch (Water Temperature) Fails To Signal Shutoff

Probable Cause

1. Incorrect Electrical Connections

Check connections to other components or install new wiring. See Wiring Diagram For Self-Powered Protection in the Wiring Diagrams section.

2. Low Water Level in Cooling System

Fill the cooling system.

3. Incorrect Setting

Test operation (trip) temperature setting and if necessary install new contactor switch with proper setting. See Specifications.

Problem 37. Contactor Switch (Water Temperature) Signals Shutoff At Low Temperature

Probable Cause

1. Incorrect Setting

Test operating (trip) temperature setting and if necessary install new contactor switch with proper setting. See Specifications.

Problem 38. Oil Pressure Contactor Fails To Signal Shutoff

Probable Cause

1. Incorrect Electrical Connections

See Junction Box Wiring Diagram For Self-Powered Protection in the Wiring Diagrams section for the correct wiring connections.

2. Incorrect Setting

Test and adjust contactor. If necessary install new contactor switch.

Problem 39. Overspeed Contactor Switch Fails To Signal Shutoff

Probable Cause

1. Incorrect Electrical Connections

Check connection, wiring and correct where necessary. See Wiring Diagram For Self-Powered Protection in the Wiring Diagrams section.

2. Incorrect Setting

Adjust setting or install new contactor switch with the correct rpm range if necessary.

Problem 40. Overspeed Contactor Signals Shutoff At Low Speed

Probable Cause

1. Incorrect Setting

Adjust setting or install new contactor switch with the correct rpm range if necessary.

Ignition System

Magneto

To make a test of the magneto on the engine, check the condition (intensity) of the spark at the spark plug.

A test of the magneto off the engine can be used to find a defect in the electrical components. The 2P2340 Magneto Test Bench is used to make the tests. Special Instruction GEG02059 gives the complete test procedure.

Finding Top Center Compression Position For No. 1 Piston

No. 1 piston at top center (TC) on the compression stroke is the starting point for all timing procedures.

Timing Pointer Cover
(1) Cover. (2) Cover.

1. Remove the cover (1) for timing pointer from the right side of the flywheel housing.

2. Remove cover (2). Use 9S9082 Engine Turning Tool to turn the flywheel in the direction of engine rotation until No. 1 piston is at top center (TC) on the compression stroke. 0 degree on flywheel.

NOTE: If the 0 degree mark on the flywheel is turned beyond the pointer in the flywheel housing, turn the flywheel back (clockwise) a minimum of 30 degrees. Do Step 2 again. This will prevent timing error caused by play in the timing gears.

3. Remove the left front valve cover. Look at the valves of No. 1 cylinder. The valves will be closed if No. 1 piston is on the compression stroke. You should be able to move the rocker arms up and down with your hand. If No. 1 piston is not on the compression stroke, do Step 4.

Flywheel Timing Marks

4. If the intake and exhaust valves for No. 1 cylinder are not closed, turn the flywheel in the direction of engine rotation 360 degrees. If both valves are now closed, this is top center (TC) compression position for No. 1 piston.

NOTE: If the 0 degree mark on the flywheel is turned beyond the pointer in the flywheel housing, turn the flywheel back (clockwise) a minimum of 30 degrees. Do Step 4 again. This will prevent timing error caused by play in the timing gears.

Timing Of Magneto To Engine

1. Turn the crankshaft in the direction of engine rotation until the No. 1 piston is coming up on the compression stroke. See the subject Finding Top Center Compression Position for the No. 1 Piston.

2. Turn the crankshaft until the desired timing mark is directly under the flywheel pointer. See the chart No. 1 Cylinder Timing.

3. The magneto timing marks (1) must be in alignment when the No. 1 piston is at the correct BTC position.

Magneto Timing Marks
(Typical Example) (1) Timing marks.

4. If not correct, remove the magneto from the engine.

5. Put timing marks (1) in the correct position with drive tang (2) positioned as shown.

6. Position the magneto drive slots in proper position for timing. The drive coupling can be pulled out of the magneto drive housing, then positioned and pushed in for engagement.

Magneto Drive Tang
(2) Drive tang. (3) O-ring seal.

7. Install the magneto. The drive tang and slot will engage.

8. Make final timing adjustment by rotating the magneto at the drive housing mounting and with the use of a timing light when the engine is running at rated speed.

NOTE: Timing must NOT be made at low idle because of the timing advance in the magneto.

To Time The Ignition System

Use a Caterpillar timing light (5P6584). Lock the timing light clip about the secondary ignition wire between No. 1 cylinder transformer and the valve cover boot. No disassembly is required.

Spark Plug Adapter

Spark Plug Adapter
(1) Adapter. (2) Seal. (3) Cylinder head.

The spark plug adapter must have the rubber boot and seal installed on the valve cover. This prevents water, dirt or other foreign material from entering the adapter. Detonation or preignition could be the result. When installing the adapter, put liquid soap on seal (2) and 5P3931 Anti-Seize Compound on the threads of adapter (1) and on the threads in the cylinder head (3). Torque the adapter to 95 ± 7 N·m (70 ± 5 lb ft).

Spark Plug And Transformer

Spark Plug And Transformer
(Altronic) (1) Transformer. (2) High voltage wire assembly. (3) Rubber boot (part of wire assembly). (4) Spark plug. (5) Seal.

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NOTICE
Both the high voltage wire (2) and seal (5) must be installed on all cylinders when running the engine. Failure to do this may allow a spark from the exposed lead to ignite crankcase vapors. Engine damage could result.

The magneto uses an externally mounted transformer (1) with a secondary high voltage wire (2) between the transformer and the spark plugs (4).

Voltage to cause the spark will change with the spark plug condition and engine load. A new spark plug in an engine at low idle will take 3,000 to 6,000 volts. At full load, this voltage will be 8,000 to 10,000 volts. When the gap of the spark plug needs adjustment the voltage needed will be over 10,000 volts. Voltage needed will go higher if plug gap adjustment is not made. Spark plugs start to cause the engine to run rough (fire erratically) when the spark plug voltage needs go higher than 10,000 volts.

Spark plug gap must be kept at 0.38 mm (.011 in). The use of 9U6695 Firing Indicator is an aid for finding ignition problems. Follow the instructions that come with the tool.

Spark plugs for ignition must be installed to a torque of 30 ± 4 N·m (22 ± 3 lb ft) with the 2P5481 Spark Plug Socket.

Manual Stop-Bypass Switch

The manual stop bypass switch (1) is located just below the instrument panel on the right side of the engine. This switch is to be used for EMERGENCY situations only. The normal way to stop the engine is to shutoff the gas supply.

Typical Example
Manual Stop Switch (1) Switch.

Fuel System

When an engine has no power, it is desirable to make a quick check with instrument to find the approximate horsepower.

Use the 1U5470 Engine Pressure Group to check the pressure in the inlet manifold.

1U5470 Engine Pressure Group

This tool group has a gauge to read pressure in the inlet manifold. Special Instruction SEHS8524 is with the tool group and gives information on the use of the group.

Correct engine operating adjustments must be made to get correct results from the instruments and test.

By checking pressure of the inlet manifold and comparison of that pressure with the TMI (Technical Marketing Information or Fuel Setting And Related Information Fiche, correct analysis can be made of engine operating efficiency. This test can be used if engine horsepower is too low, but with no other condition of engine problem.

Gas engines can burn a wide range of gaseous fuels. BTU content of fuel is a measure of the power content of the fuel. The higher BTU content fuels need less gas pressure to get a specific horsepower.

Low octane fuels burn so fast that the timing must be set back. With early timing and low octane fuel, the fast burning fuel burns too much before the piston goes over top center. The result of this is "knocking."

The air fuel ratio adjustment is made by changing the gas pressure. Too much gas makes a "rich mixture" and not enough gas makes a "lean mixture." Either causes a loss of power. The air-fuel ratio at no load is controlled by the gas regulator. The air fuel ratio at normal load is controlled by the load adjusting valve.

The BTU HHV (high heat value) of gaseous fuels is the unit of measurement of fuel heat content. The BTU LHV (low heat value) content is more important. The combustion procedure forms carbon dioxide and water, but, the heat needed for conversion of water into vapor is lost to the engine. The heat that can be used in the fuel is the LHV of the fuel. As a rule, the LHV is 10 percent less than the HHV on natural gas. When BTU HHV is given, remember to change the specification to BTU LHV so the result is correct.

Make reference to the Operation and Maintenance Guide for more information on fuels.

Initial Adjustments

Carburetor Control Linkage

(1) Lever. To install:

a. Hold throttle plate closed.

b. Loosen lever bolt and rotate lever to closed angle (A) of:

T.A. engine with EG3P actuator ... 40 degrees

c. Retighten bolt.

d. Drill 3.0 mm (.12 in) hole through lever and shaft. Install pin (2).

(2) Pin.

(3) Nut. On G3412, tighten nut on both ends of rod to a torque of ... 68 ± 14 N·m (50 ± 10 lb ft)

(4) Control rod (typical). To install:

a. Hold carburetor lever (1) in closed position.

b. Hold governor or actuator lever in shutoff position. (Refer to subject Governor Lever or Actuator).

c. Adjust rod (4) to fit between lever (1) and lever of governor or actuator. (For mounting location on governor or actuator lever, refer to subject Governor Lever or Actuator).

d. Install and tighten rod (4). There must be no binding in full travel of control linkage.

Actuator lever

Top View

(1) Control rod (typical) to carburetor. Install on outside of lever (2) as shown.

(2) Lever. To install, hold actuator control shaft in shutoff position. Install and tighten lever (2) to shaft at angle (A) of:

G3408 T.A. ... 20 degrees

G3412 T.A. ... 12 degrees

(3) Studs. Tighten to a torque of ... 17 ± 5 N·m (13 ± 4 lb ft)

Gas Leaks

Combustion gases leaking from natural gas engines can be a danger to safety. After there has been work on the fuel system, use 6V7100 Gas Detector Group to find gas leaks.

Instructions for use and maintenance of the 6V7100 Gas Detector Group, Special Instruction SEHS8216, are included with the group.

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 of the air inlet or exhaust system.

Air flow through the air cleaner must not have a restriction of more than 381 mm (15 in) of water difference in pressure.

Back pressure from the exhaust (pressure difference measurement between turbocharger exhaust outlet and atmosphere) must not be more than 686 mm (27 in) of water for turbocharged engines.

Checking Aftercooler Operation

4C6500 Digital Thermometer Group

Use the 4C6500 Digital Thermometer Group to check the operation of the aftercooler.

Operating Manual NEHS0554 gives the procedures for using the 4C6500 Digital Thermometer Group.

Turbocharger

If any unusual sound or vibration in the turbocharger is noticed, a quick check of bearing condition can be made without disassembling the turbocharger. This can be done by removing the piping from the turbocharger and inspecting the compressor impeller, turbine wheel and compressor cover. Rotate the compressor and turbine wheel assembly by hand and observe by feeling excess end play and radial clearance. The rotating assembly should rotate freely with no rubbing or binding. If there is any indication of the impeller rubbing the compressor cover or the turbine wheel rubbing the turbine housing, recondition the turbocharger or replace with a new or rebuilt one.

End clearance is best checked with a dial indicator. Attach a dial indicator with the indicator point on the end of the shaft. Move the shaft from end to end making note of the total indicator reading.

End play for the turbocharger should be 0.08 to 0.25 mm (.003 to .010 in). If end play is more than the maximum end play, rebuild or replace the turbocharger. End play less than the minimum end play could indicate carbon build up on the turbine wheel and the turbocharger should be disassembled for cleaning and inspection.

Checking Turbocharger
Rotating Assembly End Play (Typical Example)

A more reliable check of bearing conditions can be made only when the turbocharger is disassembled and the bearings, shaft journal and housing bore diameters can actually be measured.

Exhaust Temperature

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.

Crankcase (Crankshaft Compartment) Pressure

Pistons or rings that have damage can be the cause of too much pressure in the crankcase. This condition may cause the engine to run rough. There will also be more than the normal amount of fumes (blowby) 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 blowby can be worn valve guides or turbocharger seal leakage.

8T2700 Indicator Group

The 8T2700 Indicator Group is used to check the amount of blowby. 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 bridge dowels that can be removed when they are worn or damaged. Replacement of these components can be made with the tools that follow.

Valves

Valve removal and installation is easier with use of the 5S1330 Valve Spring Compressor Assembly and 5S1322 Valve Keeper Inserter.

Valve Seat Inserts

Tools needed to remove and install valve seat inserts are in the 6V4805 Valve Insert Puller Group. Special Instruction SMHS7935 gives an explanation for the procedure to remove the valve seat inserts. For easier installation, lower the temperature of the insert before it is installed in the head.

Valve Guides

Tools needed to remove and install valve guides are the 5P2396 Driver Bushing and 7S8859 Driver. The counterbore in the driver bushing installs the guide to the correct height. Use a 1P7451 Valve Guide Honing Group to make a finished bore in the valve guide after installation of the guide in the head. Special Instruction SMHS7526 gives an explanation for this procedure. Grind the valves after the new valve guides are installed.

Checking Valve Guide Bore

5P3536 Valve Guide Gauge Group

Use the 5P3536 Valve Guide Gauge Group to check the bore of the valve guides. Special Instruction GMG02562 gives complete and detailed instructions for use of the 5P3536 Valve Guide Gauge Group.

Bridge Dowel

Use a 5P0944 Dowel Puller Group with a 5P0942 Extractor to remove the bridge dowels. Install a new bridge dowel with a 5P2406 Dowel Driver. This dowel driver installs the bridge dowel to the correct height.

Bridge Adjustment

When the head is disassembled, keep the bridges with their respective cylinders. Adjustment of the bridge will be necessary after the valves are ground or other reconditioning of the cylinder head is done. The bridge should be checked and/or adjusted each time the valves are adjusted. To check for wear use a dial indicator to measure the amount of wear on the bridge seat. Make sure the contact point on the dial indicator is small enough in diameter to get an accurate measurement.

Dimensions For Reconditioning Bridge Seat
(A) Minimum dimension after reconditioning ... 16.51 mm (.650 in). (B) Allowable wear before reconditioning ... 0.13 mm (.005 in).

Use the bridge again if the wear is 0.13 mm (.005 in) or less. When the wear seat is worn more than the allowable limit, the worn surface of the seat can be ground flat. The maximum amount of material that can be removed is 0.38 mm (.015 in). If the seat cannot be made flat, replace the bridge. Reconditioning of the wear seat can only be done once.

Use the procedure that follows to make an adjustment to the bridge.

NOTE: Valves must be fully closed.

Bridge Adjustment
(Typical Example)

1. Put engine oil on the bridge dowel in the cylinder head and in the bore in the bridge.

2. Install the bridge with the adjustment screw toward the exhaust manifold.

3. Loosen the locknut for the adjustment screw and loosen the adjustment screw several turns.

4. Put a force on the bridge with a finger to keep the bridge in contact with the valve stem opposite the adjustment screw.

5. Turn the adjustment screw clockwise until it just makes contact with the valve stem. Then turn the adjustment screw 30 degrees more in a clockwise direction to make the bridge straight on the dowel, and to make compensation for the clearance in the threads of the adjustment screw.

6. Hold the adjustment screw in this position and tighten the locknut to 28 ± 4 N·m (22 ± 3 lb ft).

7. Put engine oil at the point where the rocker arm makes contact with the bridge.

Valve Lash Setting

NOTE: Valve lash is measured between the rocker arm and the bridge for the valves.

NOTE: The bridge should be checked and/or adjusted each time the valve lash is adjusted.

Valve Adjustment
(Diesel Engine Shown)

To make an adjustment to the valve lash, turn the adjustment screw in the rocker arm. Valve lash adjustments can be made by using the procedure that follows:

1. Put No. 1 piston at top center (TC) on the compression stroke. Make reference to Finding Top Center Compression Position For No. 1 Piston.

2. See chart Crankshaft Positions For Valve Lash Setting for the adjustment of all the valves with only two crankshaft positions.

3. Loosen the locknut for the push rod adjustment screw and turn the screw counterclockwise to increase the valve lash.

4. Put a feeler gauge of the correct dimension between the rocker arm and bridge contact surface. 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 the nut for the adjustment screw to a torque of 28 ± 4 N·m (22 ± 3 lb ft) and check the adjustment again.

G3408 Cylinder And Valve Location

G3412 Cylinder And Valve Location

Exhaust Bypass Group

Exhaust Bypass Group
(1) Air inlet port. (2) Diaphragm. (3) Spring. (4) Jam nut. (5) Screw. (6) Poppet valve. (7) Base assembly. (8) Diaphragm retainer. (9) Cover assembly. (10) Breather location.

These engines have watercooled adjustable wastegates for variable turbocharger boost pressure. The following set of charts have been developed to set the wastegate for altitude conditions or to maximize the throttle angle for a given load. High throttle angles (60) to 70 degrees) allow for minimum fuel consumption.

The wastegate is adjusted by setting the engine to the maximum load that it will be subject to. This load setting can be less, but no more than rated load. Then identify which chart to use; either high pressure gas or low pressure gas. Identify engine model and speed. The number at the intersection of the model row and the speed column is the pressure differential between the turbocharger boost and the manifold pressure. There are taps available in both the intake manifold and the turbocharger boost line for taking pressure measurements.

The wastegate can now be adjusted until the measured pressure matches the pressure found in the charts. If the pressure is too low, turn the wastegate screw clockwise. If the pressure is to high, turn the wastegate screw counterclockwise.

The procedure described above pertains to altitude setting for the adjustable wastegate at any load up to maximum. By using this procedure, the engine's fuel consumption will be minimized.

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.

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:

1. Oil leakage between worn valve guides and valve stems.

2. Worn or damaged piston rings, or dirty oil return holes.

3. Compression ring not installed correctly.

4. Oil leakage past the seal rings in the impeller end of the turbocharger shaft.

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 increased engine temperature.

Measuring Engine Oil Pressure

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

The 1U5470 Engine Pressure Group can be used to check engine oil pressure.

1U5470 Engine Pressure Group

This tool group has a gauge to read oil pressure in the engine. Special Instruction SEHS8907 is with the tool group and gives instructions for the test procedure.

1. Be sure that the engine is filled to the correct level with SAE 10W-30 oil. If any other viscosity of oil is used, the information in the Engine Oil Pressure Graph does not apply.

2. Connect the 1U5470 Engine Pressure Group to the main oil manifold at location (1).

Oil Manifold On Left Side Of Engine
(1) Pressure test location.

3. Operate the engine to get it up to normal operating temperature.

4. Keep the oil temperature constant with the engine at its rated rpm, and read the pressure gauge.

NOTE: Make sure engine oil temperature does not go above 115°C (239°F).

5. On the Engine Oil Pressure Graph, find the point that the lines for engine rpm and oil pressure intersect (connect).

Engine Oil Pressure Graph

6. If the results do not fall within the "ACCEPTABLE" pressure range given in the graph, find the cause and correct it. Engine failure or a reduction in engine life can be the result if engine operation is continued with oil manifold pressure outside this range.

NOTE: A record of engine oil pressure, kept at regular intervals, can be used as an indication of possible engine problems or damage. If there is a sudden increase or decrease of 70 kPa (10 psi) in oil pressure, even though the pressure is in the "ACCEPTABLE" range on the graph, the engine should be inspected and the problem corrected.

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 to not have the ability to supply enough lubrication to the engine components.

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 cause cavitation and loss of oil pressure. If the bypass valve of the oil pump is held in the open (unseated) position, the lubrication system cannot get to a maximum pressure. Oil pump gears that have too much wear will cause a reduction in oil pressure.

Oil Filter Bypass Valves

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 Passage)

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

Piston Cooling Tubes (Jets)

When engine is operated, cooling jets direct oil toward the bottom of the piston to lower piston and ring temperatures. If there is a failure of one of the jets, or it is bent in the wrong direction, seizure of the piston will be caused in a very short time.

Use the 5P8709 Piston Tool Group to check and adjust the alignment of piston cooling jets.

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. A broken oil passage can also be the cause.

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

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. The oil pressure of the engine will not get low just because the oil cooler has a restriction.

Also check the oil 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.

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.

NOTE: Water pump seals. A small amount of coolant leakage across the surface of the "face-type" seals is normal, and required, to provide lubrication for this type of seal. A hole is provided in the water pump housing to allow this coolant/seal lubricant to drain from the pump housing. Intermittent leakage of small amounts of coolant from this hole is not an indication of water pump seal failure. Replace the water pump seals only if a large amount of leakage, or a constant flow of coolant is observed draining from the water pump housing.

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 cooling system 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

4C6500 Digital Thermometer Group

The 4C6500 Digital Thermometer Group is used in the diagnosis of overheating (engine hotter than normal) or overcooling (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 Operating Manual NEHS0554.

8T2700 Blowby/Air Flow Indicator Group

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

9U7400 Multitach Group

The 9U7400 Multitach Group is used to check the fan speed. The Operator's Manual, NEHS0605 gives the operating instructions for this tool.

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.

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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.

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

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.

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.

NOTE: The correct pressure that makes the pressure cap open is on the pressure cap and is also in the Specifications module.

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. Operate the pump group and get a pressure reading on the gauge that is 20 kPa (3 psi) more than the pressure marked 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 five minutes, the radiator and cooling system does not have leakage. If the reading on the gauge goes down and you do not see any outside leakage, there is leakage on the inside of the cooling system. Make repairs as necessary.

Gauge For Water Temperature

4C6500 Digital Thermometer Group

If the engine gets too hot and a loss of coolant is a problem, a pressure loss in the cooling system could be the cause. If the gauge for water temperature shows that the engine is getting too hot, look for coolant leakage. If a place can not be found where there is coolant leakage check the accuracy of the gauge for water temperature. A temperature gauge of known accuracy can be used to make this check. Also, the 4C6500 Digital Thermometer Group may be used.

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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.

Water Temperature Gauge

Start the engine and run it until the temperature is at the desired range according to the test gauge or 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 must be the same as the test gauge or thermometer within the tolerance range in the chart.

Water Temperature Regulators

1. Remove the regulator from the engine.

2. Heat water in a pan until the temperature is 98°C (208°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. The distance must be a minimum of 9.53 mm (.375 in)

6. If the distance is less than 9.50 mm (.374 in), make a replacement of the regulator.

Belt Tension Chart

Basic Block

Piston Ring Groove Gauge

A 5P3519 Piston Ring Groove Gauge is available for checking ring grooves with straight sides. For instructions on the use of the gauge, see the Guideline For Reusable Parts; Pistons And Cylinder Liners, SEBF8001.

Piston Ring Groove Gauge

Connecting Rods And Pistons

Use the 7M3978 Piston Ring Expander to remove or install piston rings.

Use the 5P3526 Piston Ring Compressor to install pistons into cylinder block.

Tighten the connecting rod nuts in the step sequence shown in the Specifications.

The connecting 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 And Main Bearings

Connecting rod bearings are available with 0.63 mm (.025 in) and 1.27 mm (.050 in) smaller inside diameter than the original size bearings. These bearings are for crankshafts that have been "ground" (made smaller than the original size).

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 0.63 mm (.025 in) larger outside diameter than the original size bearings.

Cylinder Block

1P3537 Dial Bore Gauge Group

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. Alignment error in the bores must not be more than 0.08 mm (.003 in). Special Instruction SMHS7606 gives instructions for the use of 1P4000 Line Boring Tool Group for alignment of the main bearing bores. The 1P3537 Dial Bore Gauge Group can be used to check the size of the bores. Special Instruction GMG00981 is with the group.

Cylinder Liner Projection

1. Install clean liners or cylinder packs (without the filler band or the rubber seals), spacer plate gasket and clean spacer plate.

2. Install bolts and washers, as indicated previously, in the holes indicated with an X. Install all bolts or the six bolts around the liner. Tighten the bolts to a torque of ... 95 N·m (70 lb ft).

3. Use the 8T0455 Liner Projection Tool Group to measure liner projection at positions indicated with and A,B,C and D. Record measurements for each cylinder. Add the four readings for each cylinder and divide by four to find the average.

4. The cylinder liner specifications are as follows:

Liner projection ... 0.025 to 0.152 mm (0.001 to 0.006 in)

Maximum variation in each cylinder ... 0.051 mm (.002 in)

Maximum average variation between adjacent cylinders ... 0.051 mm (.002 in)

Maximum variation between all cylinders ... 0.102 mm (.004 in)

5. If the liner projections are out of specification, try rotating the liner or install the liner in another bore to see if the measurements improve.

6. If the liner projections are all below the specifications or low in the range, 0.025 mm (0.001 in) or 0.051 mm (0.002 in), try using a thinner spacer plate. These plates are 0.076 mm (.003 in) thinner than the regular plate and they will increase the liner projection, thus increasing the fire ring crush. Use these spacer plates to compensate for low liner projections that are less than 0.076 mm (.003 in) or if the inspection of the top deck reveals no measurable damage directly under the liner flanges, but the average liner projection is less than 0.076 mm (0.003 in).

NOTE: Do not exceed the maximum liner projection of 0.152 mm (.006 in). Excessive liner projection will contribute to liner flange cracking.

7. With the proper liner projection, mark the liners in the proper position and set them aside.

8. When the engine is ready for final assembly, the O-ring seals, cylinder block and upper filler band must be lubricated before installation.

If the lower O-rings are black in color, apply liquid soap on the lower O-ring seals and the cylinder block. Use clean engine oil on the upper filler band.

If the lower O-rings are brown in color, apply engine oil on the lower O-ring seals, the cylinder block and the upper filler band.

NOTE: Apply liquid soap and/or clean engine oil immediately before assembly. If applied too early, the filler bands may swell and be pinched under the liners during installation.

Flywheel And Flywheel Housing

Heat the ring gear to install it. Do not heat to more than 315°C (600°F). Install the ring gear so the chamfer on the gear teeth are next to the starter pinion when the flywheel is installed.

Face Run Out (Axial Eccentricity) Of The Flywheel Housing

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

8T5096 Dial Indicator Group Installed

Checking Face Runout Of The Flywheel Housing
(A) Bottom. (B) Right Side. (C) Top. (D) Left side.

1. Fasten a dial indicator to the crankshaft flange 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.

3. With dial indicator set at 0.0 mm (.000 in) at location (A), turn the crankshaft 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 0.30 mm (.012 in), which is the maximum permissible face run out (axial eccentricity) of the flywheel housing.

Bore Runout (Radial Eccentricity) Of The Flywheel Housing

8T5096 Dial Indicator Group Installed.

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.

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 crankshaft to put the dial indicator at (A). Adjust the dial indicator to "0" (zero).

Checking Bore Runout Of The Flywheel Housing

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

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

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

8. Add lines I and 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

Face Runout (Axial Eccentricity) Of The Flywheel

Checking Face Runout 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.

2. Set the dial indicator to read 0.0 mm (.000 in).

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
(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 0.0 mm (.000 in).

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.

Checking Flywheel Clutch Pilot Bearing Bore

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

Vibration Damper

Damage to or failure of the damper will increase vibrations and result in damage to the crankshaft. It will cause more gear train noise at variable points in the speed range.

Vibration Damper
(1) Vibration damper outer case.

Make an inspection of outer case (1) for dents or other damage to the vibration damper. Dents in the outer case can cause a failure of the damper.

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. A load adjustment knob on the top permits the current being drawn from the battery to be adjusted to a maximum of 100 amperes. The tester is cooled by an internal fan that is automatically activated when a load is applied.

The tester has a built in 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.

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 checks 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

Show/hide table

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.

Before any testing is done on the electrical system, the batteries should be checked for good connections and must be at least 75% (1.225 Sp Gr) fully charged.

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 to load test a battery that does not hold a charge when in use. Refer to Operating Manual SEHS9249 for more detailed instructions on use of the 4C4911 Battery Load Tester. See Special Instruction SEHS7633 for the correct procedure and specifications to use when testing batteries.

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.

To check for correct output of the alternator, see the Specifications module.

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% (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.

Starting System

Use the multimeter in the DCV range 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 multimeter to the connection (terminal) for the battery cable on the solenoid. Put the other lead to a good ground. A zero reading is an indication that there is a broken circuit from the battery. More testing is necessary when there is a voltage reading on the multimeter.

The solenoid operation also closes the electric circuit to the motor. Connect one lead of the multimeter 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 multimeter. A reading of battery voltage shows the problem is in the motor. The motor must be removed for further testing. A zero reading on the multimeter 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 multimeter lead fastened to the connection (terminal) for the small wire at the solenoid and the other lead to the ground. Look at the multimeter and activate the starter solenoid. A voltage reading shows that the problem is in the solenoid. A zero reading is an indication that the problem is in the start switch or the wires for the start switch.

Fasten one multimeter lead to the start switch at the connection (terminal) for the wire from the battery. Fasten the other lead to a good ground. A zero reading indicates a broken circuit from the battery. Make a check of the circuit breaker and wiring. If there is a voltage 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 a short circuit, loose connections and/or dirt in the motor.

Pinion Clearance Adjustment

When the solenoid is installed, make an adjustment of the pinion clearance. The adjustment can be made with the starter motor removed.

Connection For Checking Pinion Clearance
(1) Connector from Motor terminal on solenoid to motor. (2) SW terminal (3) Ground terminal.

1. With the solenoid installed on the starter motor, remove connector (1).

2. Connect a battery, of the same voltage as the solenoid, to the terminal (2), marked SW.

3. Connect the other side of the battery to ground terminal (3).

4. Connect for a moment a wire from the solenoid connection (terminal) marked MOTOR to the ground connection (terminal). The pinion will shift to crank position and will stay there until the battery is disconnected.

Pinion Clearance Adjustment
(4) Shaft nut. (5) Pinion. (6) Pinion clearance.

5. Push the pinion toward the commutator end to remove free movement.

6. Pinion clearance (6) must be 8.3 to 9.9 mm (.33 to .39 in).

7. To adjust pinion clearance, remove plug and turn nut (4).

8. After the adjustment is completed, install the plug over adjustment nut (4) and install connector (1) between the MOTOR terminal on the solenoid and the starter motor.

Instruments And Gauges

Water Temperature Sending Unit

Sending Unit for Water Temperature
(1) Terminal (2) Nut (3) Bulb

1. Connect an ohmmeter between terminal (1) and nut (2). Put bulb (3) in a pan of water. Do not let the bulb have contact with the pan.

2. Put a thermometer in the water to measure the temperature.

3. Take resistance readings at the temperatures shown in the Specifications.

4. If a unit does not have the correct resistance readings, make a replacement of the unit.

Mechanical Gauges For Oil Temperature

To check these gauges, put the bulb of the gauge in a pan of oil. Do not let the bulb touch the pan. Put a thermometer in the oil to measure the temperature. Make a comparison of temperatures on the thermometer with the temperatures on the direct reading gauge.

Mechanical Gauges For Oil Pressure

To check these gauges connect the gauge to a pressure source that can be measured with accuracy. Make a comparison of pressure on the gauge of test equipment with the pressure on the direct reading gauge.

Overspeed Contactor Switch (Mechanical)

1. Install 6B0344 Tachometer Drive Adapter between the tachometer drive and the overspeed contactor. On G3408 engines, the 5L8184 Tachometer Drive Adapter must also be installed between the 6B0344 Tachometer Drive Adapter and the overspeed contactor. The 6B0344 Tachometer Drive Adapter provides a 1 to 2 increase drive ratio. The 5L8184 Tachometer Drive Adapter has a 1 to 1 drive ratio and is used only to provide clearance for the overspeed contactor on the G3408 engine.

2. Determine the overspeed setting using the chart shown. For rated speed not shown in chart, use 118 percent of rated speed ± 25 rpm.

3. Identify (for reassembly) and disconnect harness wires from C (common) and NO (normally open) terminals of the overspeed contactor. Insulate each disconnected wire with tape.

4. Reset the overspeed contactor by pressing the button on top of the overspeed contactor case.

5. Connect the 6V7800 Multimeter to the C and NO terminals of the overspeed contactor. Check for continuity. If there is continuity, replace the overspeed contactor.

6. Remove the tag wire and loosen three lockscrews (1). Adjust the contactor all the way out by turning the contactor base CCW until the end of the screw slots are against the lockscrews.

7. Start the engine and, using an engine tachometer accurate to ±1 percent, run the engine to 1/2 of the overspeed setting rpm.

8. Adjust the overspeed contactor setting by gradually turning the contactor case CW until the overspeed contactor relay trips as indicated by a continuity reading on the 6V7800 Multimeter between the C and NO terminals. If the overspeed contactor is turned all the way CW and the multimeter shows no continuity, replace the overspeed contactor.

9. Tighten three lockscrews (1).

10. Shut off the engine. Remove the 6V7800 Multimeter from the overspeed contactor. Reconnect the harness wires to the C and NO terminals of the overspeed contactor.

11. Reset the overspeed contactor by pressing the button on top of the overspeed contactor case.

12. Restart the engine and observe the overspeed set point rpm by rapidly increasing engine rpm until engine rated speed is reached or until the overspeed contactor relay trips as indicated by automatic engine shutdown. If the engine automatically shuts down before the engine rated speed is reached, then proceed to the next step. If the engine does not automatically shut down before engine rated speed is reached, and wiring and connections are correct, then replace the overspeed contactor.

13. If the observed overspeed set point rpm is within ±12 percent of 1/2 of the overspeed setting, then the overspeed contactor is properly adjusted. If the overspeed set point rpm is not within ± 12 rpm of 1/2 of the overspeed setting, then repeat the procedure starting with Step 3.

14. Shut off the engine. Remove the 6B0344 Tachometer Drive Adapter and, if used, the 5L8184 Tachometer Drive Adapter from between the tachometer drive and overspeed contactor. Reinstall the overspeed contactor.

15. Install lockwire to three lockscrews (1).