Cummins ISX11.9 CM2250 – Service Manual Fuel in the Lubricating Oil

Bulk oil supply is contaminated

Check the bulk oil supply. Drain the oil and replace with non-contaminated oil. Replace the oil filters. Refer to Procedure 007-013 and
Procedure 007-037 in Section 7.

Electronic fault codes active or high counts of inactive fault codes

Refer to Section TF in the Fault Code Troubleshooting Manual, Bulletin
4022225, for fault code troubleshooting information.

Fuel pump seal is leaking

Perform the fluorescent dye tracer test to confirm the fuel leak. Replace the fuel pump if necessary. Refer to Procedure 005-016 in Section 5.

Engine idle time is excessive

Low oil and coolant temperatures can be caused by long idle times (greater than 10 minutes). Shut off the engine rather than idle for long periods. If idle time is necessary, raise the idle speed. Refer to Section TF in the Fault Code Troubleshooting Manual, Bulletin
4022225, for fault code troubleshooting information.

Fuel drain line restriction

Check or replace the fuel lines, check valves, or tank vents as needed. Refer to
Procedure 006-012 in Section 6
.

Injector hold-down clamps are loose

Tighten the hold-down clamps. Refer to
Procedure 006-026 in Section 6
..

Injector o-rings are damaged or missing

Remove and check the injectors. Replace the injector o-rings. Refer to
Procedure 006-026 in Section 6 ..

Injector is malfunctioning

Perform the automated cylinder performance test. Replace injectors as necessary. Refer to
Procedure 006-026 in Section 6
.

Injector sealing washer is not correct

Remove the injectors and verify the injector sealing washer thickness. Refer to
Procedure 006-026 in Section 6
..

Cylinder head is cracked or porous

Pressure test the cylinder head. Refer to Procedure 006-013 in Section 6 to disconnect the fuel drain line connection at the rear of the cylinder head. Pressure test the fuel drain drilling in the cylinder head. Refer to
Procedure 002-004 in Section 2.

Gear pump is malfunctioning

Check the gear pump output pressure. Replace the gear pump if necessary. Refer to
Procedure 005-016 in Section 5
.

Internal engine damage

Analyze the oil and inspect the filters to locate an area of probable damage. Refer to
Procedure 007-083 in Section 7
.