Roldie78

2013 A8 4.0T 90k - As many others have experienced, I noticed strong suction when removing my oil cap with the car running. This was accompanied by a loud whistling sound. Having read the thread on this, it was clear the PCV/Oil Separator needed to be replaced.

I just had this done for $1,500 yesterday. While this took care of the sound, I still have the exact same negative pressure in the motor with the oil cap being difficult to remove. With this, the car also idles at around 600rpm.

What else could be causing the pressure if not the PCV? Has anyone replaced their PCV but it didn’t fix the problem? This is very frustrating. Any help is greatly appreciated.

2010A8Lsport

My 2010 A8L is exhibiting the same symptoms and I just removed my oil separator today to see if it could be cleaned. I think I'll just have to buy a new one as the original doesn't look serviceable at all. I was hoping that replacing the oil separator would cure my high crankcase vacuum....

I will update this post if I figure anything out.

the_duke

Are these serious posts? Crankcase vacuum is normal.

2010A8Lsport

I have owned in excess of 160+ cars from all walks of life including high end european, and personally wrenched every one of them and I have never experienced an excessively high vacuum situation that I have with this Audi 4.2.

So to answer your question, this is a serious post and question.

the_duke

There is no such thing as excessive vacuum. But if it helps high vacuum increases the pressure differential across the ring package, producing an improved ring seal. The improved ring seal allows the use of a low-tension (reduced friction) piston rings. This helps with both fuel efficiency and horsepower.

2010A8Lsport

If it was designed to have extremely high vacuum as you say they would all exhibit this trait, and they do not?

Raymond Coletta

when i take the oil fill cap off of my sons car it sounds the suction hose of my shop vac , this doesn’t sound normal for any engine but it’s a audi 2013 s7 4.0

A8L_New_England

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Is that a question?
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Seriously, what do you mean by "extremely high vacuum"? If you can pull the cap off, I wouldn't consider it that.
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Maybe just stop taking the cap off, and resign yourself to whatever is happening inside your engine.
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OberklasseA8

New 4.0 V8 SSP - AudiWorld Forums

check out the PDF. It goes into detail on PCV and recirculation. I haven't studied in detail so I cannot speak from experience, but the motor has some serious design around engine pressure and cooling.

Curtis Mueller

Roldie78, Did you ever get an answer to this? I can barely pull the oil cap off with car running and PCV just replaced under Audi bulletin.