Quick question...should I be able to blow air through both sides of the valve? I removed the valve during a thermostat replacement, and cleaned it by spraying MAF cleaner into the inlet and outlet, until oil residue was no longer apparent. Afterwards, I was able to blows though either end without any restriction. The car has 11.4k miles on it.

 

Anyone?

 

The PVC valve is a one way valve. If held horizontally you should only be able to blow through it one way.

 

I just put a new pcv valve on my 09 V8V and could easily blow through it in both directions.

 

Relieved to hear, thanks for the reply! That said, other PCVs I've come across behave like embdenb said...one way only. Wonder what it looks like inside?

 

Just curious, where you holding the valve horizontally ( the way it would be installed in the car) when you were able to blow through it both ways.?

 

I can’t recall 100%, but I don’t believe so. I cannot imagine that would make much difference though.

 

It might.

AKAIK In the original design there was a "Ball" or object built into the device that rests over the orifice’s opening of the tube that connects to the engine's valve cover.
The blow-by pressure from the engine had to be strong enough to "move" this ball off the orifice and allow the engine vacuum from the intake manifold to draw the blow-by into the engines combustion’s chamber to be re-burned.

This “ball” was built into the PCV design because the design was never to offer unrestricted vacuum to the engine’s crankcase, but rather to relieve the pressure in the crankcase after it reached a predetermined level.

Now if the PCV valve was not upside down when you attempted to blow through it from the side that connects to the intake manifold, then the “ball” would block the orifice and prevent air flow from that direction.

Later PCV valve designs changed where the “ball” was replaced by a spring; (see attached photo) however the design purpose remained the same, releasing pressure from the engine’s crankcase after a predetermined pressure level has been reached.

 

Yes, held it in installed position