We have an '01 A4 1.8T, and engine oil is finding its way into the coolant overflow tank. The mechanic is at a loss as to what is causing this. He has checked the turbo (no leaks), oil cooler (no leaks), compression tests (no leaks), and the spark plugs are clean. Can you think of another way oil is leaking into the coolant system?

Any help would be greatly appreciated.

Thanks,

Darrell

 

Has your tech done a smoke test? That might help figure out where it's coming from.

 

Sounds like the oil cooler seal is blown, allowing oil to flow into the coolant system. Chances are you'll have to replace that oil cooler, and get a system flush while you're at it.

https://www.audiforums.com/m_563033/tm.htm

 

I know this might sound absolutely bonkers but has anyone topped the oil up in the coolant expansion tank?? its been done before failing that ill go with Trey25

 

maybe someone just connected a hose to hte wrong place?

 

+1 for oil cooler. Head gaskets are rarely ever an issue with the 1.8t engine. Its a fairly inexpensive part, if went through the trouble of taking it off to check for internal leaks he might as well had just replaced it. I dont even see how he could check for leaks in it without cracking it open anyways. Hmmm. Replace the oil cooler.

 

I would guess it is an interior seal in the oil cooler. Have him check the compression in the cyls to rule out head gasket (unlikely). Are you sure it is oil. Did you top up the coolant with green stuff. It will turn your coolant brown.

 

mechanic is stumped...get a new mechanic. sorry i dont have much to add other then playing off of your title