Leaky black tank flush line

[FLtravelers]

Last time we were out, I wanted to flush the black tank because I knew the Monty would be parked for a couple months without use. After about 30 seconds with the water on, (drain valve open) water started coming out from the ceiling of the basement, and all kinds of other places where water shouldn't come out of. Shut it off to resolve when I got home.

Today I figured it was time to look at it. Did the same thing. I took the panel off from behind the hose connections. Flush line goes up through the floor and disappears. Looks like under the tub. With a flashlight, I looked into the pocket door opening. Couldn't see the line, but could tell that the wall at the back of the tub was open. Pocket door was wet six feet up from spray from the leak.

Has anyone had this issue and resolved it without pulling the tub?

[dustinc02]

In your pantry you should have a plastic access cover. Pull that off (It has double sided tape holding it on.) Behind that is the black tank anti siphon valve. I would bet that is where your problem lies. Mine went early on as well.

[FLtravelers]

Thanks Dustin. That would have made sense, except mine doesn't have an access panel - YET.

Steve

[tim43]

Mine blew early on, had it replaced and even bought a spare valve. But, haven't used it since. Too much flooding when it broke the first time. I just use a lot of water in the black tank and when leaving, dump, refill and dump again. Takes time, but avoids a potential flood again.

[FLtravelers]

Tim - that was my other thought. Just don't use it. Then I don't have to fix it.

[FLtravelers]

Another stupid installation by Keystone.



You can see the pressure being exerted on the backflow by the piping. That's what cracked it.



In their desire to hold the piping in place, they created a stress point on the valve.

I know how to fix it with the proper spacer to hold the piping apart, but I can't get at it without cutting more holes in the back of our pantry.