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Old 08-04-2017, 01:01 PM   #1
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Newmar MADP air brake inversion valve releasing air


This maybe a simple question. I have been working on parking brake problem and resolved it or perhaps part of it with a bad hose.

My parking brake button kept popping out and not setting the parking break. I found a brake line in the rear was bad and replaced that and now it appears to be working.

During the troubleshooting, I noticed that while the parking break is released I hear a significant amount of air being released from the inversion valve at a brass covered exhaust port. I put pictures below.

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Old 08-04-2017, 01:05 PM   #2
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Newmar MADP air brake inversion valve releasing air

Sounds like you may have a blown diaphragm on brake canister. More specifically the diaphragm for the releasing the spring brake.
I had same symptoms and found this to be the problem last spring.

Edit. I see you are able to release parking brake. Might be the other diaphragm.
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Old 08-04-2017, 01:21 PM   #3
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That valve has a guick release valve made into it. ....
When you apply the parking brake that's where the air exhaust that you hear. If air is leaking there the valve will need replacement.

Generally when a brake chamber diaphragm fails you'll also have a air leak at the back side of the chamber.

It doesn't look to terrible to replace.
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Old 08-04-2017, 01:24 PM   #4
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Thanks for your reply. I am able to release the parking brakes which would mean the emergency side is good. Is there a way to test if the primary brake side is ok?

Also, this inversion valve is located above the two large tanks under the drives and passengers seats.
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Old 08-04-2017, 01:46 PM   #5
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@mackwrech Thanks for your help.

On mine, the quick release valve which releases the large burst of air when you set the parking brake is above the rear axle. As mentioned above this what I was told was an inversion valve is located toward the front above what the 3rd smaller tank. That might be called a wet tank. I am not real solid on the air system parts.

I have been watching some video to get a basic understanding
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