Cummins ISX11.9 CM2250 – Service Manual Fuel in Coolant

Broken valve seat insert

Check the bulk coolant supply. Drain the coolant and replace with non-contaminated coolant. Replace the coolant filters. Refer to
Procedure 018-004 in Section V in the Operation and Maintenance Manual, ISX11.9 CM2250, Bulletin 2883444 .

Fuel heater is malfunctioning (if equipped)

Check the fuel heater and replace, if necessary. Refer to the OEM service manual.

Injector o-rings and sleeves are damaged. Injector o-rings are missing

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

Cylinder head is cracked or porous

Remove the intake and the exhaust manifolds. Check for evidence of coolant leaks. If necessary, operate the engine at low idle. Pressure test the cylinder head. Refer to Procedure 002-004 in Section 2
.