2017 Mallard IDM 245 - black tank flush hasn't worked since day 1

[ScottyP5947]

Hi there -
I bought a Mallard IDM245 and have had great luck with it overall. I have tried to use the black tank flush a few times and each time, it doesn't do anything. It has make a quiet squeaking sound but not what I would expect with a black tank flush. It doesn't seem to have any flow - it doesn't change the rate of flow coming from the black tank either.

Where would I begin troubleshooting this issue?

I have just resorted to filling and emptying as a means of flushing. I can get the water crystal clear with this method but I am sure there is some residue.

Thanks for your suggestions!

Scott

 

[danemayer]

Hi Scott,

There are 2 possible causes that I'm aware of based on a few posts over the past year.

The pex tubing could be kinked somewhere cutting the water flow. You may have to drop the coroplast underbelly to investigate this possibility.

The factory might have connected the black tank flush anti-siphon valve backwards. The valve is usually located behind a bathroom wall - you may or may not have an access panel. If you can see the pex tubing on the back side of the fitting where you connect your hose, you may be able to look up with a good flashlight to see where the valve is mounted. Maybe. The pex connections can be removed to check this, and corrected.

If you're under warranty, this might be something you leave to your dealer.

 

[NP_Chief]

Just a thought... but are you removing your water pressure regulator before you flush?

 

[ScottyP5947]

Thank you both for the input! I will take a look in the underbelly to see what is going on in there.
As for the pressure reg - I have tried all sorts of pressure from mild to what I consider pretty high and all it does is change the pitch of the sound that comes out from the flush area, but with no real water flow.

I'll let you know what I find!

Scott

 

[Gary521]

It is very common to have the anti-siphon valve not functioning. Mine never worked either. A lot of us have bypassed this valve altogether and placed a check valve in the flush line.

 

[JohnDar]

It’s also fairly common for that PoS ASV to break up in a wall cavity and spray water all over the area below it.


Sent from my iPhone using Tapatalk

 

[ScottyP5947]

I think my anti siphon valve and plumbing is inside my bathroom, under the sink. Pretty easy access. I'll try to look soon.
As for adding a check valve myself - I'm sure it's covered online - is it with off the shelf plumbing parts?

Thanks!
Scott

 

[cemill]

I had the same problem on our 2015 Big Country.
The anti syphon valve is located behind the shower wall . There is a round access panel that can be removed.

Turned out the valve was installed backwards from the factory. Must have been late Friday afternoon for the guy that installed it.
I cut the lines, reversed the valve and installed new pex clamps and now works as it should.