Cummins ISX11.9 CM2250 – Service Manual Lubricating or Transmission Oil in the 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 008-006 and
Procedure 008-018 in Section 8.

Lubricating oil cooler transfer housing or lubricating oil cooler support is cracked or porous

Check the oil cooler transfer housing and the support. Refer to
Procedure 007-003 in Section 7
.

Lubricating oil cooler is malfunctioning

Check the oil cooler. Refer to
Procedure 007-003 in Section 7
.

Torque converter cooler or hydraulic oil cooler is malfunctioning

Remove and inspect the cooler cores and o-rings. Refer to the OEM service manual.

Cylinder head gasket is leaking

Check the cylinder head gasket. Refer to
Procedure 002-004 in Section 2
.

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
.

Cylinder liner is corroded or cracked

Check the cylinder liners for corrosion or cracks. Contact a Cummins® Authorized Repair Location

Cylinder block is cracked or porous

Inspect the cylinder block. Refer to
Procedure 001-026 in Section 1
.