What would cause your black tank valve to work open when traveling?

**jh2pizza** · 08-09-2019, 07:47 AM

Twice now, I have had the surprise waiting for me when I removed the cap to drain the tanks at a dump station. THe black tank does not leak when sitting, but when traveling home, we stop at the truck stop dump station to empty and the valve has worked open. I took it to the dealer and $120 later they said there is nothing wrong with the valve.

**JCZhome** · 08-09-2019, 08:00 AM

Not sure what's causing it but if it's still happening you should go get your $120 back.

**ncitro** · 08-09-2019, 08:10 AM

Originally Posted by jh2pizza

Twice now, I have had the surprise waiting for me when I removed the cap to drain the tanks at a dump station. THe black tank does not leak when sitting, but when traveling home, we stop at the truck stop dump station to empty and the valve has worked open. I took it to the dealer and $120 later they said there is nothing wrong with the valve.

The pipe from the black tank valve to the outlet is fairly long, and not pitched super well in some units. When you are "done" and close the valve there can still be stuff in the pipe between the valve and the cap that isn't flowing. Once you continue down the road it migrates down the pipe to the cap and leaves you with a surprise when you open the cap. I recommend an additional safety valve just before the cap, then no surprises when you remove the cap

https://www.amazon.com/dp/B000BGHYJS..._i6xtDb28MK6MQ

For a further improvement on mine I glued it on in addition to the bayonet fitting, once I had the whole thing come off when I tried to just unscrew the valve.

**boyscout** · 08-09-2019, 09:25 AM

Originally Posted by jh2pizza

Twice now, I have had the surprise waiting for me when I removed the cap to drain the tanks at a dump station. THe black tank does not leak when sitting, but when traveling home, we stop at the truck stop dump station to empty and the valve has worked open. I took it to the dealer and $120 later they said there is nothing wrong with the valve.

@ncitro has likely nailed the answer to your question.

We have the issue on our Solitude 310GK. The valves don't leak - we've proved that. However after patient and careful draining - black first, then gray tanks - including tipping the trailer up and down using its hydraulics we travel down the road and end up with as much as a half-gallon or more of stuff at the outlet cap, sometimes with chunks in it. Not nice. The dealer claims to have looked at the problem and found nothing wrong.

It seems clearly to be a problem with the dump plumbing AFTER each of the respective tank valves. On our trailer the three tanks empty into a common manifold from where they exit through a single pipe to the outlet cap. Somewhere in there stuff is getting trapped, moved out only when the trailer is subjected to start/stop forces and rolling side-to-side down the road.

I've now installed one of these valves at the outlet cap so at least I can more easily control when the latest surprise is going to exit the outlet.

https://www.amazon.com/Valterra-T58-...s%2C172&sr=8-1

**JCZhome** · 08-09-2019, 10:00 AM

In our Momentum I've learned to leave the sewer hose hooked up until I raise the rear levelers and then raise and lower the front levelers slowly to excise anything that's still in the pipes after the gate is closed.

**Fsalmy** · 08-09-2019, 10:36 AM

Originally Posted by ncitro

The pipe from the black tank valve to the outlet is fairly long, and not pitched super well in some units. When you are "done" and close the valve there can still be stuff in the pipe between the valve and the cap that isn't flowing. Once you continue down the road it migrates down the pipe to the cap and leaves you with a surprise when you open the cap. I recommend an additional safety valve just before the cap, then no surprises when you remove the cap

https://www.amazon.com/dp/B000BGHYJS..._i6xtDb28MK6MQ

For a further improvement on mine I glued it on in addition to the bayonet fitting, once I had the whole thing come off when I tried to just unscrew the valve.

What did you use for glue?

I have the same issue, when removing the sewer hose bayonet fitting, the whole Valtera valve wants to twist off. And has.

**ncitro** · 08-09-2019, 10:40 AM

Originally Posted by Fsalmy

What did you use for glue?

I have the same issue, when removing the sewer hose bayonet fitting, the whole Valtera valve wants to twist off. And has.

Just ABS plastic pipe glue. I actually put a screw through mine the first time it came off because it was all I had and was frustrated at the mess. Later when I got it home i took the screw out and glued it proper.

**D2Reid** · 08-09-2019, 10:55 AM

Originally Posted by Fsalmy

What did you use for glue?

I have the same issue, when removing the sewer hose bayonet fitting, the whole Valtera valve wants to twist off. And has.

Glue is rather a permanent solution and those valves will fail eventually, takes several years of full time use. I put a set screw in the top of the pipe to hold the Valtera valve on. I put it on the top so that it would not tend to leak nor collect things as the tanks are flushed.

I do this because I remove the Valtera valve when we travel in winter. That little bit of water freezes the valve closed.

**ncitro** · 08-09-2019, 11:00 AM

Originally Posted by D2Reid

Glue is rather a permanent solution and those valves will fail eventually, takes several years of full time use. I put a set screw in the top of the pipe to hold the Valtera valve on. I put it on the top so that it would not tend to leak nor collect things as the tanks are flushed.

I do this because I remove the Valtera valve when we travel in winter. That little bit of water freezes the valve closed.

I had considered that, but found that even with my screw at the top it leaked a little. I figured down the road I would have to cut the valve off and I could just glue a coupling and more pipe on if needed. For winter camping I suppose you could just leave it open rather than remove it.

The screw probably would have worked long term, but I felt better with the glue after it all came apart when trying to just unscrew my hose. I think part of it too is the Rhino hose goes on pretty tight, and I need to turn it pretty good to get it off.

**boyscout** · 08-09-2019, 11:57 AM

Originally Posted by JCZhome

In our Momentum I've learned to leave the sewer hose hooked up until I raise the rear levelers and then raise and lower the front levelers slowly to excise anything that's still in the pipes after the gate is closed.

I do this too as mentioned in my note above. It doesn't do the trick. What I haven't tried is tipping the trailer side-to-side with the levelers, but I'd guess that's a pretty hairy thing to do and it would only prove what I already know: that the drain plumbing was badly-designed and/or badly installed by Grand Design.