Troubleshooting Caterpillar 3612 and 3616

Troubleshooting Caterpillar 3612 and 3616 Engines

Troubleshooting Problems

Cat-3612

Engine Crankshaft Will Not Turn
Probable Cause
1. Problem with the air starting motor
Refer to the information on the air starting motor in this section.
2. Fluid in the cylinders
Open the manual valves (Kiene valves) on each cylinder. If the engine is not equipped with the manual valves,remove the cylinder pressure relief valve or the plug. Inspect the cylinders for fluid while the crankshaft is being turned.
3. Problem with accessory equipment (hydraulic pumps, air compressor, etc)
Disconnect the driven equipment until the faulty accessory can be found. Repair the faulty accessory. Replace the faulty accessory.
4. An internal problem prevents the turning of the engine crankshaft.
If the crankshaft cannot be turned, the engine must be disassembled. After disassembling the engine, inspect the engine for other internal problems. Possible internal problems include the following conditions:
Bearing seizure
Piston seizure
Valve and piston contact

The Engine Will Not Start. The Governor Terminal Shaft Does Not Move.
Probable Cause
1. Control linkage binds
The engine can start when the engine is cold. When the oil is hot the governor does not develop the oil pressure that is needed to move the linkage. Check the linkage effort and correct the linkage effort.
2. No signal to actuator solenoid
Refer to the Woodward PGEV & PGE Locomotive Governors, SENR6444 or to the 2301A Electric Governors For Generator Sets, SENR3585.
3. Low oil pressure in the governor
The governor oil pump relief valve may be stuck in the open position or the valve may be leaking. This may be corrected by disassembly and cleaning of the governor. Refer to Caterpillar 3161 Governor, SENR3028. Check for plugged oil supply passages from the engine.

The Engine Will Not Start. The Governor Terminal Shaft Moves.
Probable Cause
1. Slow cranking speed
Refer to "Air Starting Motor Turns Slowly or the Air Starting Motor has a Loss of Power".
2. Low quality fuel or water in fuel
Remove the fuel from the fuel tank. Install new fuel filters. Put a good grade of clean fuel in the fuel tank. Refer to Supplement, SEBU7003, "Caterpillar 3600 Series Diesel Engine Fluids Recommendations For Lubricants, Fuels, and Coolants".
3. No fuel to fuel injectors
Check the fuel level in the fuel tank and fill the fuel tank, if necessary. Use the priming pump in order to remove any air from the fuel system.
Install new fuel filters, if necessary. Fuel lines that are blocked should be cleaned and fuel lines that are broken should be replaced. Check the fuel transfer pump for damage and/or wear.
The governor linkage is not connected to the internal rack linkage. This condition can exist after a governor has been assembled incorrectly during an overhaul. Ensure that the governor linkage is correctly engaged.
4. Low fuel pressure
At starting rpm, the minimum fuel pressure from the fuel transfer pump must be 415 kPa (60 psi). If the fuel pressure is less than 415 kPa (60 psi), change the fuel filters. After changing the fuel filters, inspect the fuel system for air in the fuel system. If the fuel pressure is still low, check the fuel bypass valve and the fuel transfer pump for correct operation.
5. Wrong fuel injection timing
Adjust the timing. Refer to System Operation/Testing and Adjusting, "Fuel Timing".
6. Air inlet shutoff valve is tripped.
Reset the air inlet shutoff valve.

Engine Overspeed
Probable Cause
1. Fuel control linkage
Inspect the fuel control linkage for one or more of the following conditions:
Incorrect assembly after overhaul
Bound fuel control linkage
Bound fuel control linkage in FUEL-ON position
Governor output lever to control housing lever out of adjustment
Make adjustment or repair.
2. Governor problem
Refer to engine governor's service literature.
3. The governor actuator is not engaged in the drive coupling.
Ensure that the governor is driven by the engine. If necessary, remove the governor and install the governor again in order to ensure that the engine is engaged correctly with the governor drive. Also, check for drive components in the governor and in the engine that are worn or damaged.

Unstable Engine Speed
Probable Cause
1. Misfire
Refer to "Misfire or Running Rough".
2. Bound linkage or worn linkage with flat spots and high clearances Inspect the linkage. Repair the linkage or replace the linkage, as needed.
3. Rough governor drive
Worn splines and/or high gear clearances can cause rough governor drive. Inspect parts and replace parts, if necessary.
4. Governor problem
Refer to engine governor's service literature.
5. Seized injector
Replace the injector.
6. Seized piston and/or stuck piston rings
Replace piston assembly and cylinder liner.

Cannot Reach High Idle Rpm
Probable Cause
1. The speed setting control shaft is not against the high idle stop.
Check the speed control linkage and the pneumatic controls for restrictions.
2. Incorrect high idle adjustment
The governor speed setting shaft is against the high idle stop and the high idle is too low. Adjust to the correct high idle. Also, check the engine fuel setting in order to ensure that the engine fuel setting is correct.
3. Speed droop adjustment is incorrect.
Refer to engine governor's service literature.
4. The speed setting solenoid adjustment of the Woodward PGEV governor is not correct.
Refer to engine governor's service literature.

The Engine's High Idle Declines After Start-up
Probable Cause
1. Loss of normal rpm
The loss of approximately 20 rpm can be expected as the engine warms to operating temperature.
2. Incorrect high idle adjustment
If necessary, make an adjustment in order to correct high idle. Also, check the engine fuel setting in order to ensure that the engine fuel setting is correct.

The Engine Cannot Be Shutdown Through the Governor
Probable Cause
1. Shut down solenoid
The solenoid may have shorted wires or broken wires. The solenoid may be stuck in the open position. Inspect the solenoid and replace the solenoid.
2. Incorrect wiring
The shutdown signal is not wired correctly. Make sure that the polarity is correct.
3. Incorrect installation of governor actuator
Ensure that the governor control lever or the actuator terminal shaft is engaged correctly with the fuel control linkage stop lever.
4. Governor in need of repair
Disassemble the governor and clean the governor components. Inspect the governor components for wear and damage. Replace parts, as needed.

Misfire or Running Rough
Probable Cause
1. Low fuel pressure
The fuel pressure at the outlet of the fuel filter housing must be a minimum of 450 kPa (65 psi) at 900 rpm. If fuel pressure is lower than the above pressure, check the following items:
Plugged fuel filters
Fuel transfer pump
Make sure that there is fuel in the fuel tank. Look for leaks or bends in the fuel line between the fuel tank and the fuel transfer pump. Look for air in the fuel system. Also look for a faulty return fuel pressure regulating valve.
2. Air in fuel system
Find the air leak in the fuel system and correct the air leak. If there is air in the fuel system, the air generally enters the fuel system on the suction side of the fuel transfer pump.
3. Leakage or breakage in fuel line between fuel manifold and cylinder head
Install a new fuel line.
4. Defect in fuel injector
When the engine runs at rated load, the exhaust manifold port temperature can be an indication of the condition of a fuel injector. Low temperature at an exhaust manifold port is an indication of no fuel to the cylinder. This may be an indication of a fuel injector with a defect. Extra high temperature at an exhaust manifold port can be an indication of too much fuel to the cylinder. This may also be caused by a fuel injector with a defect. If any one cylinder varies by more than 50 °C (90 °F), there may be a problem with the fuel injector.
5. Faulty inlet or exhaust valve
When the engine runs at rated load, the temperature of an exhaust manifold port can be an indication of thecondition of the inlet and exhaust valves. Extra high temperature at an exhaust manifold port can be an indication of a valve with a defect. If any one cylinder has an exhaust port temperature that is 50 °C (90 °F) higher than the average of the exhaust port temperatures on the bank, there may be a problem with a valve.
6. Wrong valve lash
Adjust the valve lash. Refer to System Operation/Testing and Adjusting, "Valve Lash and Valve Bridge Adjustment".
7. Wrong fuel injection timing
Adjust the timing. Refer to System Operation/Testing and Adjusting, "Fuel Timing".
8. Bent pushrod or broken pushrod
Replace the pushrod, if necessary.
9. Fuel has cloud point higher than atmospheric temperature. cloud point is the temperature when wax is formed in the fuel.
Drain the fuel tank, fuel lines and fuel manifolds. Change the fuel filter. Fill the tank with fuel that has the correct cloud point. Remove the air from the system with the priming pump. Some installations require the use of fuel heaters in order to ensure fuel flow. Also, the use of fuel heaters prevents filter blockage from fuel wax.
10. Excessive engine load
Lighten the load in order to observe any change in the engine operation.

Engine Stalls at Low Rpm
Probable Cause
1. Low fuel pressure
The fuel pressure at the outlet of the fuel filter housing must be a minimum of 450 kPa (65 psi) at 900 rpm. If fuel pressure is lower than the above pressure, check the following items:
Plugged fuel filters
Fuel transfer pump
Make sure that there is fuel in the fuel tank. Look for leaks or bends in the fuel line between the fuel tank and the fuel transfer pump. Look for air in the fuel system. Also look for a faulty return fuel pressure regulating valve.
2. Low engine idle rpM
Adjust the governor. Ensure that the idle rpm setting matches the rpm that is listed in Technical Marketing Information (TMI).
3. Defect in fuel injector
Refer to "Misfire or Running Rough".
4. Engine accessories
Check engine accessories for damage and make repair or replacement. If necessary, disconnect the accessories and test the engine.


CAT SENR3593 - 3612 and 3616 Engines

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