Possible Causes
• Misreading oil level
• Oil leak • Engine crankcase vent
• Oil level
• Intake and exhaust system
• One or more turbochargers
• Low compression (cylinder pressure)
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Note: The steps are listed below in order of probability. Perform these steps in sequence.
1. Misreading oil level
A. Accurately measure fuel and oil consumption over 50 engine operating hours.
Result: Oil consumption is less than 0.08% of fuel consumption.
Oil consumption meets specifications. Put the unit back into operation.
Result: Oil consumption is greater than 0.08% of fuel consumption.
Proceed to test step 2.
2. Oil leak
A. Check the engine for oil leaks.
B. Check for engine oil in the coolant.
Result: Engine oil leak confirmed.
Repair: Eliminate the cause of the engine oil leak.
Result: Engine oil is present in the coolant.
Repair: Please refer to Troubleshooting and Diagnosis, "Coolant Contains Engine Oil".
Oil leak not determined. Proceed to test step 3.
3. Engine Crankcase Vent A. Check for blockage in the engine crankcase vent. B. Check for excessive engine oil at the vent outlet.
Result: Engine crankcase breather is blocked or clogged.
Repair: Clear the blockage or clog.
Result: Excessive engine oil is spraying from the vent outlet.
Repair: Investigate the cause of excessive engine oil in the vent airflow. If the vent filter element is saturated with engine oil, replace the filter.
Result: No engine oil is spraying from the breather.
Proceed to test step 4.
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4. Engine Oil Level
A. Check if the engine oil level is too high.
Result: Engine oil level is high.
Repair: Ensure the oil is not contaminated with fuel. Refer to Troubleshooting, "Fuel Contaminated Oil".
Ensure the oil is not contaminated with coolant. Refer to Troubleshooting, "Coolant Contaminated Oil".
Drain excess oil.
Result: Oil level is normal.
Proceed to step 5.
5. Intake and Exhaust System
A. Check the air filter clogging indicator (if equipped).
Check the intake and exhaust systems for the following problems:
· Signs of dust ingress
· Blockage
· Damage to intake and exhaust pipes and hoses
Result: Air filter resistance indicator is active or air filter is clogged.
Repair: Ensure the air filter is clean and serviceable. Replace the air filter if necessary.
Result: Intake or exhaust system is blocked, clogged, or damaged.
Repair: Repair the intake or exhaust system if necessary.
Result: Intake or exhaust system is normal.
For engines with a single turbocharger, proceed to test step 6.
For engines with twin turbochargers, proceed to test step 7.
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6. Turbocharger
Note: This step applies only to engines equipped with a single turbocharger.
Note: The turbocharger installed on this engine is a non-repairable component. If any mechanical fault is present, the turbocharger must be replaced.
A. Check that the turbocharger's oil drain is not obstructed or restricted.
B. Remove the turbocharger compressor outlet pipe and check for signs of internal oil leakage.
Result: Turbocharger return oil is blocked or clogged.
Repair: Clear the blockage or clog. Replace the return oil pipe if necessary.
Result: Internal oil leakage exists in the turbocharger.
Repair: Replace the turbocharger. Check the front surface of the diesel particulate filter (DPF) for oil contamination.
If oil is found on the DPF inlet surface, refer to Troubleshooting and Repair, "Oil in the Exhaust System".
The problem has been resolved by the inspection and repair.
Result: Turbocharger is normal.
Proceed to test step 8.
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7. Turbocharger
Note: This step applies only to engines equipped with twin turbochargers.
Note: The turbocharger installed on this engine is a non-maintainable item. If any mechanical fault is present, the faulty turbocharger must be replaced.
A. Check and confirm that the turbocharger's oil drain is not obstructed or restricted.
B. Remove the turbocharger compressor outlet pipe and check for internal oil leakage from the turbocharger.
Repair: Replace the faulty turbocharger. Check the front surface of the diesel particulate filter (DPF) for oil contamination.
If oil is found on the DPF inlet, please refer to Troubleshooting and Repair, "Exhaust System Oil".
The problem has been resolved by inspection and repair.
Result: Turbocharger is normal.
Proceed to test step 8.
8. Low Compression (Cylinder Pressure)
A. Perform a compression test. Please refer to System Operation, Testing and Adjustment, "Compression - Test".
Result: Compression test results are outside technical specifications.
Repair: Investigate the cause and eliminate any faults.
