Dustin Musselman

I've done lots of reading of articles, forums, etc. I have a 2004 Audi A4 1.8T and my valve cover gasket is leaking. I have a feeling this is due to the PCV issue people have had. I'd like to replace it along with the gasket but every time I think I've come to a definitive conclusion on which part it is, I'm confused by another article and/or post. Is the PCV the disc shaped plastic part at the back of the engine? Or is it a T shaped connection under the intake manifold? For example, ECS sells two:

(a) https://www.ecstuning.com/b-genuine-...mm/06a129101f/

(b) https://www.ecstuning.com/b-genuine-...cv/06a103245f/

Are these both essentially doing the same thing? And which one are people talking about when they say "Replacing the PCV fixed the valve cover leak"?

Just looking for something definitive so I don't replace the wrong one and blow out another gasket. Thanks in advance!

old guy2

The valve on the back of the valve cover is technically the PRV (Pressure Regulating Valve). It allows and controls the air flow in both directions.

The valve underneath the intake manifold is the PCV valve. It only allows flow in one direction. When the intake manifold is under vacuum the PCV pulls air through the block. The air enters the block through the PRV.

When under boost the PCV closes and any block pressure build up is drawn through the PRV into the TIP.

dorothian

Correct!

Dustin Musselman

Thanks! I got parts delivered and replaced my thermostat (per other thread) and also got PCV and regulator. Noticed that ALL of my breather hoses are full of a yellowish foam. See pictures. I'm cleaning them out as best I can. Old PCV appears to work fine. The regulator is full of gunk. I'm replacing jusythe regulator for now and think I'm going to order the 034 motorsports PCV kit because a few of my hoses look like they could be replaced anyways.

Question. Is this normal and to be expected if valves aren't working or do I have another problem elsewhere I need to diagnose? Looks like liquid moisture almost.

old guy2

That build up is normal when the block breathers aren't working properly. Moisture builds up in the block and mixes with the oil vapor. After you get the air circulating through the block properly the moisture will get purged once the block is up to operating temperature.