Black Tank Issues

[NomadMen]

We’re only a few months into full-timing and we cannot seem to get an issue with our black tank fixed. We’ve had mobile repair people out.

Symptoms and steps we’ve taken are as follows:

• The tank backs up into the toilet.
• Emptying the tank appears to go fine although a lot of solids do not seem to come out.
• We can run the black tank flush until the water coming out is practically clear. But the toilet continues to back up.
• We have used the flexible wand into the toilet. There does not seem to be a pyramid.
• We’ve treated it with the standard stuff, Commando, and Unique. These have worked so well that the sensors indicate the tank is nearly empty.
• Occasionally the water in the toilet will go down like it’s been fixed. But the problem returns even if we avoid using any toilet paper.
• Once it recedes, every flush is accompanied by an air bubble like the vent may be blocked.
• At least two mobile repair people have examined the issue and done some or all of the above and the water receded. The tech declares it fixed, takes our money, and goes their merry way. But the clog returns. (The last tech used a plunger — which I thought was a big no-no. I don’t know if I want to call him back.)

We wonder if there's an issue with the vent and that's where the clog might be since we get the bubble or burp when we can flush. On the roof of our 2022 Solitude 378MBS-R, there are two black vents and one white. Would I be correct to assume the WHITE vent pipe is the black tank and the two BLACK vent pipes are to the two gray tanks?

Some owners have suggested it has to do with a floating plastic disk from when a hole was punched into the black tank causing the problem. Is this a possibility?

We’re now in an area (just north of Atlanta) where it takes weeks to get a tech to come out. Most dealerships are backed up months and, since we full-time, that’s not the best option.

Any ideas what to do?

I’m thinking of calling different plumbers in the area and seeing if any have experience with RVs.

[TedS]

I would suspect that the black tank vent pipe has slipped into the black tank and gets blocked by the water level after several flushes and then the toilet begins its burping. That condition may also cause slow emptying until the water drops below the end of the pipe.

Someone with a 378MBS will have to answer the roof cap question.

[Country Campers]

NomadMen

There could definitely be a "pyramid", this is common if not enough water is used. The vent pipe may also be an issue where it may be inserted too far into the black tank. The white vent on the roof is not a tank vent, this is an attic vent for the area between the roof and the ceiling. The 2 black vents would be for the tanks, the one closest to the drivers side or street side should be for the black tank. You could check the vent connection at the tank by removing the false wall in the pass thru which could give you access to the vent piping. You probably will not be able to see much but you may be able to see much but might find something as all of the plumbing pipes should be visible in that area. The hole cut out has been an issue for some time, if it drops in the tank they generally do not try to retrieve it. An inspection camera would be ideal to see what is going on in the tank. This will have to be inserted from the outside hose drain connection and go up thru to get a good view, from the toilet down may help as well. You could get your own camera from online. Sorry for your troubles and hope we can help you get it fixed.

Brian

[howson]

Some owners have suggested it has to do with a floating plastic disk from when a hole was punched into the black tank causing the problem. Is this a possibility?

Yes...but I think TedS ' and Brian's comment about the vent line being inserted into the tank too far (or "slipping down" into the tank) is the most likely cause.

We’re now in an area (just north of Atlanta) where it takes weeks to get a tech to come out. Most dealerships are backed up months and, since we full-time, that’s not the best option. Any ideas what to do?

I'll be sending you a PM with an option.

Howard

[d2reid]

This may or may not help, but in reading what you have done my next step would be to get a garden hose and put a fixed nozzle on the end that creates kind of a pressure washer effect. I would shove the hose in until it hits something solid, hopefully the bottom of the tank, keep in mind the pipes make a few twists. Then turn the hose on full blast and wiggle it around some. You'll need a helper to watch what comes out and to turn the water off should there be a blockage and/or backup.

I am pretty sure the real diagnosis and fix is going to require removing the tank and inspecting it, full timers worst nightmare. I would also be looking at repair facilities outside of my immediate area. When I couldn't get my furnace fixed at my ski resort winter home I packed it up and took it to Las Vegas, bypassing many repair facilities that "couldn't get to it until...". Many small town dealers are in their slow period and would welcome a major repair.

Our first big repair we tried staying in a Motel 6 with the animals, pretty miserable. The next one we did an air-bnb, much more comfortable.

[GoodH20]

We had the same issue with our black tank bubbling back up into the toilet when flushing which finally plugged up. I ran a small camera down the black pipe and discovered a 11” x 2” piece of wood lodged in the lowest of the two 45 degree elbows. In order to remove it I pulled the toilet, unbolted the toilet flange and cut the black pipe just above the lowest 45 degree elbow to remove the wood.