Oil in antifreeze reservoir

[Phil Mesmer]

Wondering why there’s oil in the antifreeze reservoir on a marine Cummins 6B but no antifreeze in the crankcase. Are the heat exchangers shot?

Topic

[donald roth]

Has the engine been overheated?   If so, Head gasket failure orwarping/cracking of head is high on the list.                                                                                  Oil pressure is higher than coolant pressure, so when breached, intrusion is initially into the coolant side.                                                                                                                         The heat exchanger does not contain any engine oil, it’s interface is between raw water and coolant.  The oil cooler is a separate item, and seldom has reason to fail.

Pressure test the coolant loop.

 

[Author]

Replies