Oiled expansion tank

[330dTso]

Hi! I just experienced some oil in the water reservoir,oil cap has no single water drop. How do I make sure if it's the gearbox or oil cooler? E46 330d

 

[Nikhil]

Drain the engine oil and check. I wouldn't suggest driving the car either until you know where the problem lies

 

[Kish2604]

Thread moved to correct sub forum...

 

[330dTso]

Ta Nikhil will try that

 

[zippy320]

Is your car an automatic or manual? whats your engine oil level like? is the car smoking etc? Is the car overheating?

Check if you notice a color to the oil , (reddish = transmission / brownish = engine) it might be a start.

I think if you open up the oil filler cap on the engine , you may be able to see some water / oil mix residue on the cap , that is if it is indeed coming from the engine, If that's the case then there may be other bigger problems.

Another cause may be the transmission oil cooler.

This was the problem on my car ,What happened on my car was that the transmission oil cooler leaked , leaking oil into the cooling system . I replaced it , drained and flushed the cooling system and all was fine , Though I would also suggest draining and flushing the transmission as well , in case oil and water mixed there as well .

I think (but im not sure ) there is also an oil cooler for the engine , you could check that out .