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Thread: Effects of bad PCV valve?

  1. #1
    Registered Newbie Constrictor's Avatar

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    Effects of bad PCV valve?

    I've never changed the PCV valve on my car. I recently hit 70k miles, and have no reason to suspect theres anything wrong with it, but since theyre only $2.99 at AutoZone, I bought one.

    What possible problems would indicate that I should do this? Will I notice any changes once I put the new one on?

  2. #2
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    If the old one still rattles when shaken, it is still good. If that's the case, you wont notice any difference by swapping it out.

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    Top down, cutout open ! Bad30th's Avatar

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    It's just a check valve to keep vacuum pressure on your crankcase. If the pressure flow reverses (pressure from intake directed back into the valve) the valve will close and prevent pressure from being pushed into the crank case. The idea is to keep a vacuum down there to eliminate blowby gases and crankcase pressure.

    No performance increase to be had by replacing it. If it goes bad it will either not close like it should or will stay closed and not vent pressure from your crankcase - like stated above it should probably be replaced every couple of years, it's cheap.

    Rattling when shaken isn't really a good test though, it may have a problem with staying open or closed. Just replace it if you have any doubt, can't go wrong for under $3.

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    Registered Member LS1 2001 Z28's Avatar

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    Mine was stuck open a hair so i had oil in my throttle body. Now 2k miles after replacement and cleaning my throttle body no oil back there.

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    Well I am new here but let me tell you about a bad PCV valve. I bought a 2000 silverado. Ran okay but I knew what I was getting into. It would not cold start/ run smooth/ and the TPS was all screwed up. Well I changed all that and the fuel pump. Still ran the same. Well to put it short the PCV was plugged solid. So now with out N2O I can run mid 11s.

  6. #6
    gettin' screwed...
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    Not to hijack your thread Constrictor... but wildchild.. You run mid 11's in a silvy without a poweradder? Go over to the truck section and post you setup if you would.
    2000 Silverado, RCSB, 2wd
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    i replaced mine @ 95k miles while doing a head swap, figured why not. the old one was still in good working order though.
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  8. #8
    line em up, load em tight texasthrottle's Avatar

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    Originally posted by Bad30th
    It's just a check valve to keep vacuum pressure on your crankcase. If the pressure flow reverses (pressure from intake directed back into the valve) the valve will close and prevent pressure from being pushed into the crank case. The idea is to keep a vacuum down there to eliminate blowby gases and crankcase pressure.

    No performance increase to be had by replacing it. If it goes bad it will either not close like it should or will stay closed and not vent pressure from your crankcase - like stated above it should probably be replaced every couple of years, it's cheap.

    Rattling when shaken isn't really a good test though, it may have a problem with staying open or closed. Just replace it if you have any doubt, can't go wrong for under $3.

    JMHO,
    Bad30th
    yep yep and yep. A bad one can leak through oil into the TB. And yeah at like 3 bucks just one of those things you do just cause.

  9. #9
    I Love Corvettes!!
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    I'm at 102k on my LT1 and I'm pretty sure it's still the original PCV too. I was going to change it until I noticed I need to remove the traction control unit in order to get at the valve. I don't think my car is suffering any ill effects from it. I honestly think that as long as you use a good oil and your engine is in good working order, you won't have a gummed up PCV.

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  10. #10
    Typing away b3av3r's Avatar

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    I just changed mine on my LS1 with 111,000 miles on it. It was still on the original and I figured at a couple bucks I should put the new one in and see if it helps with any oil consumption.

    The old one seemed fine, but I'm not real sure how to check if it was still good or not.


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