ISM, ISMe, and QSM11 – Lubricating or Transmission Oil in the Coolant

Bulk coolant supply is contaminated

Check the bulk coolant supply. Drain the coolant and replace with non-contaminated coolant. Replace the coolant filters. Refer to Procedure
008-018 in Section 8.

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 block is cracked or porous

Remove the oil pan. Pressure-test the cooling system to check for leaks. Refer to
Procedure 001-027 in Section 1.