PCV valve question

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j - 29 Jan 2007 23:38 GMT

I replace my PCV valve once a year whether it needs it or not. The last
changeout was around 6 months ago. Today I pulled the PCV valve out of the
hole that it plugs into in the valve cover and the engine did not rev up
like usual when the PCV valve is pulled out. I put my finger over the hole
on the bottom of the PCV valve and it was sucking air into the PCV valve.
However, when I pulled the PCV valve off of the rubber angle-shaped boot
that connects it to the hose that goes to the engine, the engine revved up
very much. I then wiped the PCV valve off, placed it into my mouth, and blew
into both ends. I was able to blow air through the PCV valve in both
directions, but I always thought that the PCV valve would not pass air both
directions. Am I correct about this? I shook the valve back and forth and I
could hear the plunger inside the PCV valve going back and forth as I was
shaking it. Although this is a fairly new valve, is it likely that it is
bad? This is on a 94 Corsica with a 6 cylinder engine.

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corning_d3 - 30 Jan 2007 01:09 GMT

That should be normal operation. You don't want the valve pulling full
vacuum. The shake test is one way of telling the condition of the
valve. A rattle is good.

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corning_d3

http://www.automotiveforums.com

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Dan_Thomas_nospam@yahoo.com - 30 Jan 2007 16:00 GMT

> I replace my PCV valve once a year whether it needs it or not. The last
> changeout was around 6 months ago. Today I pulled the PCV valve out of the
[quoted text clipped - 10 lines]
> shaking it. Although this is a fairly new valve, is it likely that it is
> bad? This is on a 94 Corsica with a 6 cylinder engine.

The valve is designed to pass a small amount of air at idle;
the manifold vacuum will pull it mostly shut, and the valve will open
as the throttle opens and vacuum falls off. It should slam shut if
there's a backfire in the manifold; that's its purpose, to keep flame
from reaching the flammable gases in the crankcase. If it didn't bang
shut you might have to pick up a lot of pieces off the road.

Dan

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Ashton Crusher - 02 Feb 2007 06:34 GMT

>I replace my PCV valve once a year whether it needs it or not. The last
>changeout was around 6 months ago. Today I pulled the PCV valve out of the
[quoted text clipped - 10 lines]
>shaking it. Although this is a fairly new valve, is it likely that it is
>bad? This is on a 94 Corsica with a 6 cylinder engine.

The valve should last at least 60,000 miles, it doesn't need yearly
replacement. I'm still running the original on my 127,000 mile 92
explorer.

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