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PCV valve rattling?

Discussion in 'Stock 1991 - 1994 Explorers' started by Corik, July 24, 2011.

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    1. Corik

      Corik Member

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      I installed a new PCV value yesterday, and when I turned on the car it was making this loud rattling noise.
      I knew it was the little thing inside making the noise but my old one didn't do this. so I popped it off and put the old one back on. (It could still rattle so I probably didn't really need a new one...ehhh $2.)

      Anyway, no noise with engine on, I went to show my dad and when I put the new one on...it sounded fine! so I thought I guess it just wasn't on good.

      BUT then today its doing it again, I took it off and put it back on but its still doing it I don't know if this is bad for the engine or not so I wanted to ask.

      Should I just get a new one? ie. its bad Or does it matter at all?
       
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    3. Roadrunner777

      Roadrunner777 Well-Known Member

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      A PCV valve, I guess most of us know, regulates the ventilation of the crankcase. An an engine runs, a small amount of air/fuel mixture gets by the cylinder rings, and left to it's own devices, the crankcase would start to develop pressure. If you take the oil filler cap off a running engine, you will probably hear and feel the pressure coming out.

      We don't want pressure in the crankcase for several reasons. It can cause leaks at gaskets, and the fuel in the mixture dilutes the oil. Up through the 50's, I guess, they simply ran a vent pipe from a valve cover to the ground and called it a day.

      Then came the PCV valve, which is little more than a slug of metal and a spring inside a plastic or sheet-metal case.

      [​IMG]

      We now draw those crankcase vapors through this valve, as the diagram shows, into the intake manifold, and back through the engine again.

      You note that the old one still rattles, so it is still good. That means the slug of metal is still free to move around inside the case. Sometimes the flow of oily crankcase vapors can cause this valve to stick. You can imagine the inside filling with crud and varnish and eventually it's just a sticky glob inside.

      The new one rattles more freely. Well, maybe there is a little bit of varnish and crud that is making the old one stick a little bit.

      Should you get a new one? No, I think either your old one or first new one will do fine. I'd probably run the new one, since the old one does not move as freely.

      Belated apologies to practically everyone that already knows how a PCV valve works, I just felt long-winded today.
       
    4. Corik

      Corik Member

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      Thanks for your reply, I understood the basic concept before. I guess I'll just deal with the annoying noise of it. It was rattling loud enough to hear it with the hood down, so I thought something was wrong. And when I touched it, there was a lot of vibration. Oh well thanks.
       
    5. Corik

      Corik Member

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      I finally got so fed up with the damn irritating noise, I decided to get a new PCV valve. This time a motorcraft and boy it was a huge difference. The noise was gone and the idle was about 150 rpm lower than usual. It just sounded better too, probably the lower rpm. Normally I idled around 1k now its about 850ish. I "think" I noticed a little more pick up and go, idk if this was just my imagination or not though.
       

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