N14 Base Engine Troubleshooting and Repair Manual – Fuel in the Lubricating Oil

Symptom Tree  t092

This is symptom tree t092
Cause Correction

Bulk oil supply is contaminated

Check the bulk oil supply. Drain the oil and replace with noncontaminated oil. Replace the oil filters. Refer to Procedures 007-037 and 007-013.


Engine idle time is excessive

Low oil and coolant temperatures can be caused by long idle time (greater than 10 minutes). Shut off the engine rather than idle for long periods. If idle time is necessary, raise the idle speed. Procedures 007-037 and 007-013


Fuel drain line restriction

Check or replace the fuel lines, check valves, or tank vents as needed. Refer to Procedure 006-012.


Top injector o?ring is damaged or injector is damaged

Perform the fluorescent dye tracer test to find the bad injector. Replace the injector or o?ring. Refer to Procedure 007-044.


Injector is malfunctioning (PT/STC)

Remove and check the injectors. Replace injectors as necessary. Refer to Procedure 006-026.


Injector cup is damaged or is not correct

Check the injector cups for damage and for correct part numbers. Refer to Procedure 006-026.


Fuel pump gear pump main shaft seals are leaking

Check the gear pump main shaft and seals. Refer to Procedure 005-016.


Cylinder head is cracked or porous

Remove intake and exhaust manifolds. Check for evidence of coolant leak. If necessary, operate engine at low idle. Pressure-test the cylinder head. Refer to Procedure 002-004.


STC oil control valve is damaged

Remove and inspect the STC valve. Refer to Procedure 006-037.

Last Modified:  29-Mar-2005