# Oil Foam in Oil Filler Cap



## GLS-S4 (Jun 6, 2005)

A friend has an A6 3.0 and we are trying to figure out why oil foam continually appears inside the oil filler cap area, especially in winter.
There are no ECU codes, car runs fine, regular oil changes with factory filter, engine reaches operating temp regularly (no short drives in cold weather, etc).
The foam looks like light beige colored whipping cream and is cleaned out of oil filler every week.
Anyone experienced this... any suggestions ?










_Modified by GLS-S4 at 2:31 PM 2/15/2007_


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## Uberhare (Jul 30, 2003)

It appears to be water in your oil. Does the foamy oil smell funny like coolant? Could also be caused by condensation inside the engine somewhere, although unlikely.


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## GLS-S4 (Jun 6, 2005)

*Re: (Uberhare)*

That's what I was thinking... moisture in the oil can cause this symptom.
Good point, I'll check for coolant smell in foam, although coolant level is not decreasing (been watching for that).
It's like the crankcase is not breathing properly or there is a source of moisture entering the engine or both.
Any suggestions of things to check ?


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## Uberhare (Jul 30, 2003)

This same thing happened to my 1989 90Q. It was caused by a collapsed breather hose which allowed moisture to build up inside the crank.
I'm not that familiar with these newer engines, so I would suggest talking to your local dealer or trusted shop. I would suspect a problem with your crankcase breather system. Maybe go thru and check to see if all hoses and fittings are in good shape and attached correctly.


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## GLS-S4 (Jun 6, 2005)

*Re: (Uberhare)*


_Quote, originally posted by *Uberhare* »_...so I would suggest talking to your local dealer...

Interestingly enough, dealer Service Manager said "It's normal, don't worry about it." Umm... yea, the default answer that creates more $ervice work!
Also interesting to note, in recent cold weather this motor just blew out the passenger side cylinder head front oil seal(s), oil now leaking onto hot exhaust when driving (30K miles on car).
I'm suspicious that the cyl head seal leak and the foam in filler cap are related, and that fixing the seal leak will only fix a symptom and not the cause.
While searching for 3.0 engine breather issues, I noted this 2.7T / 2.8 issue that many people suffered thru until better understood, sounds similar...
http://forums.audiworld.com/a6/msgs/486032.phtml
All hoses appear intact and there is alot of plumbing that we do not want to disturb unnecessarily. Does anyone know of some checks that we can do for common crankcase vent problems on the 3.0 engine?


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## CorradoG602 (Jan 22, 2007)

*Re: Oil Foam in Oil Filler Cap (GLS-S4)*

the condition is normal. there is nothing to worry about. I see tons of 2.0s, 1.8Ts and V6s like this. Its just moisture build up on the cap.


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