PCV valve question

[daught]

A friend's 1.8 has a lot of pressure in the valve cover. I took his PCV out. I tried blowing in the direction air should be flowing (valve cover towards intake manifold) air flows but when I blow harder the valve locks and prevents further air flow. Is this normal operation?


To clarify further.

Blowing lightly from bottom to top allows air to pass
Blowing harder blocks air flow

Blowing from top to bottom does not allow air flow

[old guy]

Looking at your picture, air should always flow freely from the bottom to the top (towards the intake manifold. No air should flow from the top through the bottom (valve body).

[daught]

Thought so. For some reason air flows initially then with more air flow the valve closes. This happens in the direction it should allow air flow. So there is no upper limit for air flow? Kinda wierd that it has an upper limit.

[old guy]

No upper limit to the flow toward the intake manifold. It sounds like the flapper disc has become dislodged. You also need to take a close look at the PRV on the back of the valve cover. When the engine is under boost the PCV closes to prevent boost pressure from entering the block and the PRV (pressure regulating valve) on the back of the valve cover allows any built up block pressure to exit into the TIP.

Here's a little detail on how it all works: Clicky click®

[daught]

What's the best way to test the PRV? I'm guessing it needs a certain pressure to open.

Also where does all the air come from in the valve cover? Is all that blow-by? He has quite a bit of air blowing out from the oil cap.

I picked up an extra oil cap. I plan to drill it and insert a test port for a vacuum gauge. It should be a great for testing the PCV system.

[daught]

I got the new PCV but it has the same upper limit. If I blow hard in it it it locks up.

I also got a PRV.

I still don't get why there is so much air coming out of the valve cover. Where is it coming from at idle?

[old guy]

I got the new PCV but it has the same upper limit. If I blow hard in it it it locks up.

I also got a PRV.

I still don't get why there is so much air coming out of the valve cover. Where is it coming from at idle?

Clicky click®

[daught]

Makes a lot of sense. Thanks.