UrS4boy

<center><img src="http://pictureposter.audiworld.com/15624/aancrankcaseventilation.jpg"></center><p>
The crankcase ventilation system on the AAN is operated mechanically and is not controlled by the ECU. The only connection (so to speak) is the ECU controls boost (and vacuum) depending on the throtttle position and the crankcase ventilation system function changes with boost/vacuum it sees.

Under boost, the oil vapour-laden crankcase air goes one way; under vacuum it goes the other. Unfortunately, the diagram and the text in the VAG143 document are in conflict.

Suffice it to say, if there is a rip in one of those hoses or the PCV (non-return) check valves is stuck open, you can have problems.

Personnally, I replaced both valves last year when I did my first FMIC.

The Pressure Control Valve in the above diagram is called a "pressure regulating valve" in ETKA and has a 034 129 101A part no. (Note: 101A has been superceded to 101B and apparently its less expensive) (Ref: Item 3, Kate's photo album 103-89)

The non-return valve in the above diagram is a check valve, aka positive crankcase ventilation valve (PCV) or in ETKA, "bleeder valve". Its a one-way ball-type check valve so it needs to be installed in the correct orientation. PN is 035 103 245A. (Ref: Item 10, Kate's photo album 103-89)

There is also something called a "flame deflector plate" ((Ref: Item 5, Kate's photo album 103-89) (PN 035 103 477A) located just downstream (towards the engine) from the pressure regulating valve. This thing is supposed to stop flames travelling in these hoses - might just be a means of condensing oil vapours - no idea. Here is a photo:

<img src="http://i117.photobucket.com/albums/o59/vasp3690/29042008673.jpg?t=1209569572">

HTH

kday

The labels on that picture are the reverse of what I would expect...

a4kquattro

I think its labeled wrong, it just doesn't make sense.


Under boost, crankcase fumes aren't going to be going into the manifold on their own. The purpose of allowing the 2nd path into the turbo inlet is that under boost, there is vacuum at that location.....

UrS4boy

<center><img src="http://pictureposter.audiworld.com/15624/crankcaseventtext.jpg"></center><p>"says" the opposite (see above). And THIS is the training info they gave their Techies. No wonder things can get muffed up in the shop.

Hanz and Franz taught by Franz and Claus.

UrS4boy

Agree about the labling. The point is IF there are tears in the hoses, there can be "boost" leaks.

Sloooo4esT

thanks Dave, gother unda control

popdemonic

Thanks Dave.Anyway,have you got my ECU part.no yet?

UrS4boy

Yes. Thanks. Email issues at work though.

eric16v

anyone have part number for these 2 valves.

The one I have for the PCV is not coming up right.

034129101a and 035103245A is what I got from etka, but I am not sure if they are correct.