Is this normal??..

[4WheelDrifter]

I think that diagram is a bit wrong.

The PCV system can always be drawn through to the turbo intake hose, as it will always see vacuum, unless maybe you have no air filter. But at idle and part throttle with no boost it can also be drawn directly into the inlet manifold.
The non-return valve is there because under boost the inlet manifold is under pressure, obviously. So therefore the PCV gasses can only pass in through the turbo intake. There should be plenty of vacuum there at that point.

Also if the non-return valve fails, it's like having a boost leak in a similar way to a leaking diverter valve.

[UrS4boy]

Surely if its plumbed in before the turbo its always under vacuum?

I think that diagram is a bit wrong. The PCV system can always be drawn through to the turbo intake hose, as it will always see vacuum, unless maybe you have no air filter. But at idle and part throttle with no boost it can also be drawn directly into the inlet manifold.
The non-return valve is there because under boost the inlet manifold is under pressure, obviously. So therefore the PCV gasses can only pass in through the turbo intake. There should be plenty of vacuum there at that point. Also if the non-return valve fails, it's like having a boost leak in a similar way to a leaking diverter valve.

This is what a VAG manual says (different than the diagram):

[4WheelDrifter]

Unfortunately, the diagram and the text in the VAG143 document are in conflict.

I see you spotted that. VAG always like to throw a bit of confusion in here and there.

[S2central.net]

This is what a VAG manual says (different than the diagram):

Out of interest - what Audi resource is that info from ?
I have a LOT of books and training material here but don't recognise that one... Just in case there any other hidden gems.

Confusion over the PCV system comes up all the time here - despite sticky threads and such... It looks quite complex I suppose if its a new thing, but the underlying principles are very simple.

[UrS4boy]

Out of interest - what Audi resource is that info from ?

VAG111 Motronic in 5 cyl 20vt engine (3B)
VAG143 AAN Motronic

Check your S2central email for a quick note

Dave F.

[europeanme]

my concern about the system being under pressure was in case I undo the pipework and get covered in all manor of "un-pleasantness!"....

another query....the 2nd picture....breather hose...are they not supposed to be clamped??... as mine appears to be one with just a push fit......and is it ok to use silicone hose to replace this, in case it is split?....they are £13+vat for a straight forward piece of hose.......

thanks for everyone's help....I should hopefully get this sorted when the wife picks my PCV up....

Mike

[S2central.net]

my concern about the system being under pressure was in case I undo the pipework and get covered in all manor of "un-pleasantness!"....

another query....the 2nd picture....breather hose...are they not supposed to be clamped??... as mine appears to be one with just a push fit......and is it ok to use silicone hose to replace this, in case it is split?....they are £13+vat for a straight forward piece of hose.......

thanks for everyone's help....I should hopefully get this sorted when the wife picks my PCV up....

Mike

Mike - you absolutely cannot use ordinary silicon hose for PCV pipes... The oil rots it. You need a flourosilicone liner - its a grey/black internal layer that provides protection from oil. Its used on all Samco boost hoses for example cos of the oil vapour whizzing about.

[europeanme]

sorry my 'bad'....
I should of stipulated it was samco type of hoses...I just want to improve my "plumbing"....

cheers for the heads up though....

[europeanme]

can anyone tell me what size the hose is for the breather??...I am having to gather info while I am 100 miles away from my local TPS/hose supplier...and my tool kit!!!...so have to ask these questions....

so I can order and get the stuff sent to my house.....