- Dirt in the engine oil
- Air inlet leaks
- Fuel leakage into engine oil
- Incorrect engine oil
- Incorrect maintenance interval for the application
- Incorrect engine settings
- Incorrect engine operating temperature
- Incorrect engine oil temperature
- Incorrect turbocharger operation
Remove dirty engine oil. Install new filter elements. Put clean oil in the engine. Check the oil filter bypass valve for a weak spring or a broken spring. Look for the source of the contamination.
Inspect the air filter for leaks. Inspect all gaskets and connections. Make repairs if leaks are found.
Fuel Leakage into the Engine Oil
Fuel leakage into the engine oil will cause high fuel consumption and low engine oil pressure. This condition may also increase the oil level in the crankcase. Long term exposure can damage the pistons, the rings, the bearings, the crankshaft, and the valve train. Make repairs if leaks are found. Install new parts, as required.
Check oil recommendations for the proper oil specifications for the engine operating conditions. Refer to the Operation and Maintenance Manual.
Incorrect Maintenance Interval
Review the oil change intervals in relation to the nature and severity of the engine application. Review the records for the engine in order to verify that the recommended intervals are being followed. Refer to the Operation and Maintenance Manual.
Check the following items for proper adjustment:
- Fuel injection timing
- Automatic timing advance unit
- Fuel setting
- Fuel ratio control
- Governor adjustment
- Valve lash
Refer to System Operation, Testing and Adjusting for more information.
Incorrect Engine Operating Temperature
Check the engine operating temperature. If the engine operating temperature is not normal, refer to Troubleshooting, "3406C Diesel Truck Engine" for possible causes.
Incorrect Engine Oil Temperature
Incorrect engine oil temperature can cause premature wear to the internal engine components. The moisture in the engine oil will not evaporate if the engine oil temperature is below oil operating temperature. This will cause sludge deposits in the crankcase. If the engine oil temperature is above normal, this will cause the oil to oxidize prematurely. Either situation can cause improper oil flow through the engine lubrication system. Refer to Systems Operation, Testing and Adjusting, "3406C Diesel Truck Engine" for further details.
Incorrect Turbocharger Operation
The turbocharger can damage the engine by increasing the inlet manifold pressure beyond the designed limits of the engine. Check the turbocharger operation. Refer to Systems Operation, Testing and Adjusting, "3406C Diesel Truck Engine" for more information.