View Full Version : PCV valve ?

11-04-2010, 08:26 PM
Well to start off, I hope I'm not asking a question that's been asked a million times. As with question I post, I try to research as much as I can. I have an 01 audi a4 with an AMW motor. Now with any other b5 a4 the PCV valve seems to be a tiny plastic check valve. I've searched my entire engine and can not find anything close. Through my internet research, I found that the pressure regulator valve (pancake valve) is the PCV valve. Does this sound correct? I can't seem to find enough info on this. Any help, diagrams, pictures.

11-04-2010, 10:24 PM
There are really 2 items that generally referred to as the "PCV valve". One is the PRV (pressure regulating valve) and the other is the breather valve. The PRV is located in the Turbo inlet pipe and is not a common failure item, although cleaning it out once in a while isn't a bad idea. The breather valve is located under the intake manifold, inside the rubber "T" joint that comes off the block breather pipe. The breather valve isn't a hugely common failure either, but it can sometimes get clogged with deposits. Generally it never really breaks, just gets clogged and needs to be cleaned out. Getting to it is very difficult.

A more common PCV system failure is a clogged suction jet pump. That is what provides the breather valve with vacuum (and boost). The small passage gets clogged and the crankcase no longer gets manifold vacuum. This greatly disables the PCV system from doing it's job. Another very common failure is the busted breather pipe. That is black plastic pipe that comes out of the block under the intake manifold. It is also one of the items that makes cleaning/replacing the breather valve tricky. If it isn't broken already, touching it will normally cause it to break into a thousand pieces.

EDIT: Here is a post I did that explains how this system works and the various parts involved:

11-07-2010, 10:11 AM
Thanks for the very detailed info. For some reason I couldn't find anything on this topic. I will be taking on the PCV system within the next couple of weeks. I'll post if I have any issues.