The Engine Crankshaft Turns Too Slowly
- Low battery voltage
- Faulty cable or connection (battery to starting motor)
- Incorrect lubrication oil
- Faulty starting motor
- Extra load
- Internal mechanical problem
Check battery voltage. If the battery voltage is less than 12 volts for a 12 volt system, or 24 volts for a 24 volt system, put a charge on the battery. If the battery will not keep a charge, load test the battery. Refer to Systems Operation, Testing And Adjusting, "Electrical System" and Special Instruction, SEHS7633, "Battery Test Procedure".
With the ignition switch in the "START" position, check the voltage at the connection of the battery cable to the starting motor. If there is no voltage, or if the voltage is low at this connection and there is good voltage at the battery, check for a faulty battery cable. Also check all connections between the battery and the starting motor.
Ensure that the proper lubrication oil is installed. Use the recommended lubrication viscosities that are listed in the Operation And Maintenance Manual.
Remove the starting motor and test the starting motor. Repair the starting motor or install a new starting motor.
Check the driveline for free movement. Disconnect the PTO drives or remove the PTO drives. Remove engine accessories and inspect engine accessories that put an additional load on the engine. The following components should be inspected:
- Air compressor
- Power steering pump
- Engine oil pump
- Hydraulic oil pump
If the engine cranks too slowly and the driven equipment has been disconnected, the engine must be disassembled. After the engine is disassembled, inspect the engine for other internal problems. Possible internal problems include the following conditions:
- Bearing seizure
- Piston seizure
- Valve and piston contact
The Engine Crankshaft Turns Freely
Note: Use the following information as a guide to help solve a hard starting problem when the engine runs properly after starting.
- Low fuel level
- Improper starting procedure
- Fuel shutoff solenoid
- Fuel waxing
- Worn unit injectors
- Leaking fuel return passage check valve
- Air in fuel or no fuel
- Insufficient rack position during cranking
- Incorrect fuel injection timing
- Low cylinder compression
Visually check the fuel level. Do not rely on the fuel gauge. The lack of exhaust smoke or the lack of intermittent firing during cranking typically indicates insufficient fuel.
Refer to the Operation And Maintenance Manual for the correct starting procedure and cold weather recommendations.
The Fuel Shutoff Solenoid should produce a click as the keyswitch is first turned to the "ON" position. If the solenoid is not heard, check for battery voltage across the solenoid terminals while the keyswitch is "ON". If voltage is not present, troubleshoot the electrical system. If voltage is present, temporarily remove the solenoid. Verify that the solenoid plunger retracts when the keyswitch is turned to the "ON" position.
For cold outside temperatures, check for the presence of fuel waxing. Refer to Troubleshooting, "Fuel Quality" for details. Check for proper operation of ether starting system and/or air inlet heater (if equipped).
For starting difficulty, only when the engine is hot, refer to Troubleshooting, "Unit Injector Cranking Rack Position ".
Leaking Fuel Return Passage Check Valve
For starting difficulty after an extended shutdown, make sure that the fuel line fittings are tight. Pay special attention to the fuel lines on the suction side of the fuel system. Repair any fuel leaks. Remove the check valve in the fuel return line. Inspect the check valve for proper operation. If a problem is found, repair the check valve or replace the check valve.
Refer to Troubleshooting, "Air In Fuel". If fuel is not present in the sight gauge in the return line, refer to Troubleshooting, "Fuel Transfer Pump".
Insufficient Rack Position During Cranking
Remove the valve cover and inspect the fuel system components for wear, for damage, or for misalignment. Refer to Troubleshooting, "Unit Injector". Measure the rack position during cranking in order to determine if the governor is providing sufficient rack movement. Refer to Systems Operation, Testing And Adjusting, "Fuel Setting Check". If the rack position during cranking is less than 5 mm (0.2 inch) check for binding in the fuel injection control linkage or check for an improper FRC fuel position.
Incorrect Fuel Injection Timing
Check fuel injection timing. Refer to Systems Operation, Testing And Adjusting for details.
Check for signs of broken piston rings, faulty cylinder head gasket, and worn cylinders or valves. If the engine runs properly after starting and there is not excessive blowby or excessive oil consumption, the cylinder compression is probably acceptable.