On my 85 turbo the small line coming from the valve cover breather goes to a fitting that Tee's off of the rear AIC hose fitting on top of the manifold. It has a check valve in it that everyone says is supposed to allow flow from the valve cover to the intake manifold but not the other way because of boost pressurizing the valve cover can blow seals etc...

Are we sure about that?

I don't understand how it would be possible, with a vent line ten times the size of this small line going directly to the pre turbo, vacuum only, intake pipe that you could pressurize the valve cover area, at least not with this check valved vent line.

However, I could see how, at high boost, with the turbo creating high vacuum, how you could create a vacuum condition inside the valve cover in which case you would want that check valve to let air into the valve cover to help keep things even in there.

More evidence is my car idles high if I have the check valve letting air into the maifold, but drops 150-200 rpm when I turn it around. I went over the car this summer I turned it to point flow towards the manifold because I figured thats how it should be and some previous owner messed it up, but now I'm thinking it was right to begin with.

I know this goes against what's accepted but you may want to consider it. I will test my theory by hooking a vacuum guage up between the pvc fitting and the hose just to be sure, but its almost 3:00 AM so it will have to wait.

posted by 216.23.59...

• PVC check valve. You guys sure about that one?, John Roberts, Tue, 11 Oct 2005 23:48:37 <-- Viewing This Message
  • question of the day - is a PCV valve made from PVC?, speegee, Wed, 12 Oct 2005 21:35:25
  • Simple answer:, Fred, Wed, 12 Oct 2005 19:00:40
  • Re: PVC check valve. You guys sure about that one?, MS, Wed, 12 Oct 2005 10:09:42
    • One more point that hasn't been discussed., Jeff Cunningham, Wed, 12 Oct 2005 13:12:42
    • Re: PVC check valve. You guys sure about that one?, JohnB, Wed, 12 Oct 2005 10:40:15
      • Re: what then, MS, Wed, 12 Oct 2005 14:06:31
        • I dunno....one on mine is capped off from factory,, JOhnB, Wed, 12 Oct 2005 15:13:47
          • Re: I dunno....one on mine is capped off from factory,, Bill S., Wed, 12 Oct 2005 20:41:30
            • Not true either, my N/A has both lines n/m, couch tour , Thu, 13 Oct 2005 13:07:46
              • My apologies, you're right...., Bill S., Fri, 14 Oct 2005 02:19:49
  • From my experiences..., Joe98, Wed, 12 Oct 2005 06:59:49
  • PCV check valve, Bill S., Wed, 12 Oct 2005 01:33:14
    • If you look at the inside of the plastic turbo duct, >>, RS , Wed, 12 Oct 2005 06:11:28
      • Re: If you look at the inside of the plastic turbo duct, >>, Dan , Wed, 12 Oct 2005 16:50:25
      • Re: If you look at the inside of the plastic turbo duct, >>, Bill S., Wed, 12 Oct 2005 08:23:38
        • Re: If you look at the inside of the plastic turbo duct, RS , Wed, 12 Oct 2005 09:50:16
        • Re: If you look at the inside of the plastic turbo duct, >>, John Roberts, Wed, 12 Oct 2005 09:05:57
          • Think about it this way..., Bill S., Wed, 12 Oct 2005 10:25:26
          • Re: If you look at the inside of the plastic turbo duct, RS , Wed, 12 Oct 2005 10:00:52
            • Re: If you look at the inside of the plastic turbo duct, John Roberts, Wed, 12 Oct 2005 11:37:55
              • Re: If you look at the inside of the plastic turbo duct, John Roberts, Wed, 12 Oct 2005 13:25:18
                • So you're saying that..., Bill S., Wed, 12 Oct 2005 13:42:29
                  • Re: So you're saying that..., John Roberts, Wed, 12 Oct 2005 15:02:44

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