- Engine oil level
- Check valve for the prelubrication system
- Prelubrication pump and motor
- Circuit for the prelubrication pump
- Prelubrication pressure switch
Check the engine oil level. Add oil until the oil level is between the "ADD" and "FULL" marks on the oil level gauge. Inspect the lubrication system for leaks.
Check Valve for the Prelubrication System
Verify that the prelube pump check valve is installed correctly. Make the necessary repairs.
If the prelube pump motor is electrical, check that the prelube pump motor is supplied with the correct voltage and current.
If the prelube pump motor is driven by pressurized gas, check that the pressure of the gas is correct.
Circuit for the Prelubrication Pump
Check the Caterpillar Electronic Technician (ET) for the following logged diagnostic codes:
- 338-5 Engine Pre-Lube Pump Relay current below normal
- 338-6 Engine Pre-Lube Pump Relay current above normal
Refer to Troubleshooting, "ECM Output Circuit (Prelubrication Oil Pump)" for information that is related to troubleshooting the circuit.
Prelubrication Pressure Switch
The prelubrication pressure switch must close in order for the starting motor relay to energize. Make sure that the switch operates in the following manner:
Measure pressure at the outlet of the prelube pump.
The prelubrication pressure switch will not close unless a pressure of 9 ± 3 kPa (1.3 ± 0.4 psi) is achieved.
Determine the cause of the low pressure. Look for leaks in the oil lines for the prelube pump. Ensure that the pump is operating correctly. Make repairs, as needed.
- When the engine oil pressure rises above 9 ± 3 kPa (1.3 ± 0.4 psi), the pressure switch closes and the circuit that is between terminals 1 and 2 becomes continuous.
- When the engine oil pressure falls below 7 kPa (1 psi), the pressure switch opens and the circuit that is between terminals 1 and 2 loses continuity.
Check Cat ET for a logged 339-5 Engine Pre-Lube Pressure Switch current below normal. If the diagnostic code is logged, refer to Troubleshooting, "Prelubrication System".