Mallard M185: Location of black water check valve

tedxas

Member
Hi fellow travelers!

I have fresh water leaking into the cabin when I run the black water flush. Does anyone know where the check valve is located in an M185?

Thank you,

Ted
 

tedxas

Member
Re: Mallard M185: Location of black water check valve / VACUUM BREAKER

Found it! In a Mallard M185, the valve is underneath the queen bed just on the other side of the wall from the city hookups for water and black water flush.

With apologies for the "action" being off-center (this was a one-person operation), you can see what was happening in the upper, lefthand corner of this image. Water is shooting out of the vacuum breaker/check valve.

Screen Shot 2019-05-03 at 2.22.02 PM.jpg

So, I took out the component. No surprise, it's the infamous B&B 571 that has received numerous complaints dating back many years. When removed, it looks like this:

IMG_0609.jpgIMG_0610.jpg

There are several options for replacing this component.

https://www.etrailer.com/question-267729.html
https://www.amazon.com/s?k=b&b+571

These are also plastic and will run you about $40. I opted for an "industrial" replacement at a cost of around $50:


Cash Acme Brass 1/2-in FNPT Anti-Siphon Vacuum Breaker

https://www.lowes.com/pd/Cash-Acme-Brass-1-2-in-FNPT-Anti-Siphon-Vacuum-Breaker/1000385647

AMERICAN VALVE Check Valve Brass 1/2-in Fnpt Swing Check Valve

https://www.lowes.com/pd/AMERICAN-VALVE-Check-Valve-Brass-1-2-in-Fnpt-Swing-Check-Valve/1000248917

B&K 1/2-in Threaded Male Adapter Nipple Fitting (3 of these)

https://www.lowes.com/pd/B-K-1-2-in-Threaded-Male-Adapter-Nipple-Fitting/1000505657

I used plumber's tape to connect the components. Then, I installed and hand-tightened the completed assembly. Finally, I added a couple of plastic clamps to hold the assembly in place. I chose plastic over metal because I didn't want the metal to eat into the PEX over time as the RV travels.

When fully assembled and installed, it looks like this:

IMG_0608.jpg

I hope this will help others get more enjoyment out of their RV.

Safe travels, everyone!
 
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