Black water gush with closed tank

[Grand Master IceMan]

Hello,

When the Black water tank is closed, and I open the outlet, a gush of black water comes out.
And obviously, there is no hose connected yet so it spills all over the ground -- yuk!

What is causing this problem? And how can I solve it?
Thanks!

[Sportsdad60]

Sounds like the black water slide valve is not closed all the way, perhaps some debris stuck, or it may need replacement/ repair.

Some minor leakage is normal. Thus the reason we empty black water first, close, then open grey water tanks last, then close.
A gush is not normal.

[Bookumdanno]

Hello,

When the Black water tank is closed, and I open the outlet, a gush of black water comes out.
And obviously, there is no hose connected yet so it spills all over the ground -- yuk!

What is causing this problem? And how can I solve it?
Thanks!

The Black Tank valve is leaking. Either the seal is bad or there something blocking it from sealing. Some people are attaching a valve between the line and cap just to prevent this surprise. https://www.campingworld.com/twist-o...1&gclsrc=3p.ds

[FT4NOW]

It isnt necessarily leaking. If you see how the tanks are plumbed, there is no pitch on the header where all the tanks connect (above the coroplast). After you've dumped your tanks and then move the RV, the residual fluid in the header is what comes out of the outlet. This is why many of us use the twist on gate valve. Sure, it's possible the black valve is leaking, but with the amount of people that have this issue, I doubt all of those valves are leaking. I even replaced my black valves and tested them to be leak free. I still had that extra fluid after I've moved the RV after dumping.

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[boyscout]

When the Black water tank is closed, and I open the outlet, a gush of black water comes out.
And obviously, there is no hose connected yet so it spills all over the ground -- yuk! What is causing this problem? And how can I solve it?
Thanks!

Depends what you mean by "gush". Others have jumped to the assumption that your tank valve has failed, but if your "gush" is up to about a half-gallon or so and then it stops you more likely have a problem that appears too frequently on Grand Design trailers, which is NOT a problem with the tank valve.

Many GD trailers have black and gray tanks dumping into a manifold, a pipe fixture with several inputs and one output to the dump outlet. Due to bad design and/or sloppy manufacturing, that manifold frequently does not drain completely when dumping. When the trailer is taken on the road the various movements cause trapped sewage to finally make its way to the dump outlet, where it waits to thrill you the next time you remove the cap.

Nobody has reported a "solution" to this problem - some have reported that the design makes it very difficult to cut and re-plumb the drain pipes to make them drain better. Therefore the most common remedy is to put a gate valve on the dump outlet, so you can remove the cap and connect a hose before releasing whatever is trapped in the dump pipe.

This is the valve most often used; it simply twists onto the dump outlet:

https://www.amazon.com/Valterra-T58-...1P1F8QFR106C6J

Unfortunately, as you'll probably see it's not in stock. It's been hard to get for months on Amazon, likely due to an explosion in RV sales. You might get lucky and find one in an RV parts store elsewhere.

Good luck.

[Grand Master IceMan]

Thanks to everyone for chiming in; it's awesome to have this Forum!
I'll get one of those Valve Gates -- when it's back in stock -- and see if that can control this flawed design.
If not, then perhaps there is a leak that needs to be checked out.
Thanks again!

[FT4NOW]

Unfortunately, as you'll probably see it's not in stock. It's been hard to get for months on Amazon, likely due to an explosion in RV sales. You might get lucky and find one in an RV parts store elsewhere.

Good luck.

They might be back in stock. I ordered 2 last week in preparation for taking delivery of our 311 for $35/each and they were delivered yesterday.

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[Ghdorn]

I did not have EXPERIENCE this problem, but saw the discussion and knew how much fun it would be. Installed the gate valve and have had no outflow experience. Better safe than sorry. It does stick out a tad past the side of our 3000qb but figure it is not a big issue.

[ckreef]

Thanks to everyone for chiming in; it's awesome to have this Forum!
I'll get one of those Valve Gates -- when it's back in stock -- and see if that can control this flawed design.
If not, then perhaps there is a leak that needs to be checked out.
Thanks again!

I had the same problem. That valve will solve the problem.

I did not have EXPERIENCE this problem, but saw the discussion and knew how much fun it would be. Installed the gate valve and have had no outflow experience. Better safe than sorry. It does stick out a tad past the side of our 3000qb but figure it is not a big issue.

Mine sticks out a little bit on my 2600rb. If another vehicle got close enough to take it off we'd probably have a much bigger issue then just the valve. In campgrounds I never get the trailer close enough to anything to worry about it.

[thunder550]

That Valterra valve was the first thing that got installed on our new 31MB. Read too many stories about the residual waste surprise when uncapping the dump pipe.

I couldn't find anything reasonably priced on Amazon or ebay, so I ordered from Walmart.

Etrailer has them in stock as well.