Test '79 aux air valve

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T.Hanson
Posts: 1693
Joined: Wed Jul 26, 2006 7:39 am

Test '79 aux air valve

Post by T.Hanson » Fri Jul 26, 2019 7:23 pm

As the engine starts and gets up to temp the piston valve opens,draws back, to allow normal air flow. Is there a way to bench test the piston is free to move,...working properly, without swapping in the entire contraption ?

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Mike W.
Posts: 2444
Joined: Wed Aug 30, 2006 12:12 am
Location: Sonoma County

Re: Test '79 aux air valve

Post by Mike W. » Fri Jul 26, 2019 7:32 pm

Which aux air valve, the A/C one or the warm up? The former is a simple solenoid valve, only accuated when the A/C compressor is on, the latter is thermal and closes as the coolant warms up. External test would be to disconnect the air side, block off both sides to prevent a vacuum leak and see if there's a change. It allows more air in when cold. Many seem to dislike them, I've had better luck with them than the later electric one on top of the V/C.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

T.Hanson
Posts: 1693
Joined: Wed Jul 26, 2006 7:39 am

Re: Test '79 aux air valve

Post by T.Hanson » Fri Jul 26, 2019 9:34 pm

Thank you for the quick reply. Who cares, the A/C in all my cars has never worked, been charged with the old freon, whatever. The windows and sunroof have worked fine.

The answer to my question seems to be,... there is no bench test. If I want to check the two extra parts units off the shelf it's going to be an exercise in swapping in the complete contraptions.

I think not until the one that's working fine, stops doing that.

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Mike W.
Posts: 2444
Joined: Wed Aug 30, 2006 12:12 am
Location: Sonoma County

Re: Test '79 aux air valve

Post by Mike W. » Sat Jul 27, 2019 2:40 pm

I misunderstood your question at first. I think you can bench test them, or at least stove top test them, just put them in a pan and heat it to boiling, you should see movement.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

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