# Check valve orientation inline from vacuum reservoir to manifold



## salz2135 (Sep 18, 2006)

Can someone post a picture of the check valve that is located inline between the vacuum reservoir and the manifold?

I'm not sure how the reservoir functions, so I can't come up with a theoretical guess on the check valve's orientation.


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## snowfox (Apr 4, 2002)

*Re: Check valve orientation inline from vacuum reservoir to manifold (salz2135)*

The reservoir is a place that "stores" vacuum. The valve should be oriented so that gases can only flow from the reservoir toward the intake manifold (the vacuum source). You can check it by blowing or sucking (I can't believe I just typed that for a public forum!!!) If you try to force air/blow through the valve and it "doesn't work", put that end toward the manifold. Vice versa if you apply vacuum / suck air through the valve. If you can't suck air through it, put that end toward the reservoir. Whichever method you use, make sure to test the valve both directions. It should only allow air to pass in one direction. If it works both ways, you need to replace the check valve.


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## salz2135 (Sep 18, 2006)

Thanks for the help.
Under what conditions does the res accumulate vacuum and under what conditions does it release the vacuum?


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## 84_GLI_coupe (Apr 3, 2001)

*Re: (salz2135)*

With the throttle closed, the intake manifold will suck air through the check valve, from the vacuum reservoir and brake booster. When you step on the brakes, the diaphragm in the brake booster pushes what little air there is out through the lines, increasing pressure (or reducing vacuum) in the reservoir.
With the engine idling, you won't get _that_ much vacuum in the intake manifold. When you're driving along and go to step on the brakes, the throttle closes and you get a much greater vacuum in the intake manifold, which sucks even more air out of the vacuum reservoir and brake booster.
As far as orientation of the check valve, you have to be able to suck on it from the intake manifold side, and not from the brake/reservoir side.


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## Eric D (Feb 16, 1999)

*Re: Check valve orientation inline from vacuum reservoir to manifold (salz2135)*


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## salz2135 (Sep 18, 2006)

school is in session. this is just what I needed.


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