N14 Base Engine Troubleshooting and Repair Manual – Lubricating or Transmission Oil in the Coolant

Symptom Tree  t108

This is symptom tree t108
Cause Correction

Bulk coolant supply is contaminated

Check the bulk coolant supply. Drain the coolant and replace with noncontaminated coolant. Replace the coolant filters. Refer to Procedure 008-018.


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 Procedures 007-047 and 007-003.


Lubricating oil cooler is leaking

Check the lubricating oil cooler for coolant leaks and cracks. Refer to Procedure 007-003.


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.


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.


Cylinder block is cracked or porous

Inspect the cylinder block. Refer to Procedure 001-027.

Last Modified:  20-Jan-2004