Coolant in oil, no oil in coolant.

I just bought a V50 T5, with the expectation I would have to work on it. PO had bought it from a dealer, but it had started to overheat on the way home. Dealer would not take it back, since it was an As-Is purchase, and it passed emissions (CO rule - must pass emissions). A mechanic had diagnosed a bad head gasket, which made sense - overheating, missing coolant, contaminated oil, and a misfire.

It ran OK, with a misfire (passed emissions, as I said) and contaminated oil , so I bought it cheap and had it towed home.

I tore into it, replaced the head gasket, timing belt, water pump, fluid change. Long job, but expected. I couldn't find a visible issue with the old head gasket, but these things can be subtle.

However, coolant is still making it's way into the oil!

I drained the oil after a short time running, and it had significant coolant.

However, coolant system is clean - no oil in it at all, which is what I'd expect, given relative pressures.

I pulled the oil cooler from the back of the engine, and tested it with air pressure. No leak there.

Where else can coolant get into the oil?!?!?

 

I have heard of issues with the oil cooler causing oil in the coolant.

 

AutoNaut:

Thanks!

I had done a test with compressed air on the oil cooler. Nothing seemed to leak between the water and oil sides. However, soon I will take the cooler out of the circuit (put a pipe between the inlet and outlet coolant hoses) and test again, with fresh oil.