Black tank leaking

Topic: Black tank leaking (Read 1287 times) previous topic - next topic

Black tank leaking

December 21, 2020, 01:59:03 pm

Whenever we put on one of our fantastic fans, we get a black tank odor. Can't smell it otherwise.

Then, I've noticed that if we travel with a full black tank, there's BT liquid in the wet-bay, and the coach smells for days.

So obviously, some sort of hole in the black tank. Is this something a regular RV place can fix, or is it something that will require going back to the Foretravel factory?

Any recommendations for a place in Quartzsite to have work done? We're going to be there anyway in a few weeks to have our air-bags and shocks replaced.

The coach is a 03' 38ft U320 with the bedroom slide.

Re: Black tank leaking

Reply #1 – December 21, 2020, 02:21:35 pm

I had a black tank with a leak in a corner. Nothing would fix it including black tank repair kits, etc. I cleaned off around the leak, sanded the area and then used my commercial epoxy resin with fiberglass cloth to cover the area of the crack as well as about 6 or 8 inches around it. Repeated with several more layers of cloth keeping the excess epoxy low. Painted the epoxy on, put cloth in place, brushed on a little more epoxy, more cloth, etc. Never leaked a drop after that.

If you can't see the crack or leak, you will have to pull the tank. Make sure the bad stuff is not coming from a connection first.

Pierce

Re: Black tank leaking

Reply #2 – December 21, 2020, 03:19:23 pm

Maybe you have an issue with the rubber grommet on top of the tank since you only notice it when the tank is full or your fan on.

Re: Black tank leaking

Reply #3 – December 21, 2020, 03:41:41 pm

Might also want to check the Studor vents. A bad one would not cause a tank leak, but would allow tank gases to escape into the coach.
I have not checked, but I presume there is one under the kitchen cabinet, bath cabinet and possible the washing machine area.

Re: Black tank leaking

Reply #4 – December 21, 2020, 05:03:23 pm

Another possible source of the odor is the wax ring under the toilet.

On my Microphor toilet (which is no longer installed) the wax ring was rolled up under the toilet. When it was reinstalled by previous owner they slid it back in place rather than connect the water after the toilet was installed. That caused the wax ring to slide and distort.

Check the AAV's first and the black tank if it is leaking, but keep this in mind.

Re: Black tank leaking

Reply #5 – December 21, 2020, 05:16:38 pm

Most 0of those will smell all of the time and not leak fluid.
The tank top must have a failure of some sort. Either the filler grommet or a crack.
You can weld the plastic , if it is plastic. You can weld the alluminum , if it is alloy. U Tube will show the details . I welded my plastic water tank a few years ago . Seems to hold . HTH, MM

Re: Black tank leaking

Reply #6 – December 21, 2020, 05:26:15 pm

Quote

there's BT liquid in the wet-bay, and the coach smells for days.

It doesn't sound like a crack in the tank. Hopefully, it's the pipe gasket or toilet seal as mentioned. If it does turn out to be the tank itself, I would follow Pierce's advice. My black tank got cracked and I was advised by the manufacturer in Elkhart that the tanks are cross linked polyethylene and cannot be repaired. I tried anyhow by taking it to a joint with a plastic welder (no dice) and on my own by trying to melt and join. Anyhow, I ended up buying a new tank from Foretravel. Probably could have saved some money if I had gone Pierce's route. Good luck.
jor

Re: Black tank leaking

Reply #7 – December 21, 2020, 05:37:08 pm

Quote from: jor – December 21, 2020, 05:26:15 pm

It doesn't sound like a crack in the tank. Hopefully, it's the pipe gasket or toilet seal as mentioned. If it does turn out to be the tank itself, I would follow Pierce's advice. My black tank got cracked and I was advised by the manufacturer in Elkhart that the tanks are cross linked polyethylene and cannot be repaired. I tried anyhow by taking it to a joint with a plastic welder (no dice) and on my own by trying to melt and join. Anyhow, I ended up buying a new tank from Foretravel. Probably could have saved some money if I had gone Pierce's route. Good luck.
jor

John..which coach had the leak the U300 ? and where was the leak exactly. I see some scuffing on the retainer bar on the balck and gray tanks.
Thx
Hans

Re: Black tank leaking

Reply #8 – December 21, 2020, 05:50:05 pm

Quote

which coach had the leak the U300 ? and where was the leak exactly.

It was on my 300. Here's a couple of photos. It was a very small crack right where the arrow is pointing. Those tanks are thick so I wouldn't worry about scuffing although you could always shim it if it's moving around.
jor

Re: Black tank leaking

Reply #9 – December 21, 2020, 05:58:50 pm

I had missed the part about liquid in the bay, so deleted my air admittance valve post. Sorry for the incomplete reading of the problem.

Is there any chance the black tank is more full than indicated? If the tank levels are read by a Javalina system, the sensors (particularly black tank) can go bad.

Re: Black tank leaking

Reply #10 – December 21, 2020, 07:38:35 pm

Quote from: jor – December 21, 2020, 05:50:05 pm

It was on my 300. Here's a couple of photos. It was a very small crack right where the arrow is pointing. Those tanks are thick so I wouldn't worry about scuffing although you could always shim it if it's moving around.
jor

Wonder what caused it to crack in that spot? Is it possible the tank froze, the &*^%$ expanded and cracked the tank. Some plastics get brittle in sub freezing-temps.

Pierce

Re: Black tank leaking

Reply #11 – December 21, 2020, 09:34:42 pm

Quote

Wonder what caused it to crack in that spot?

I had that rig at Foretravel getting some stuff done. While it was plugged in they tried to back it out of the bay. The plug ripped out. They fixed it. When I got home I noted the leak (olfactory). My theory: During the event the cable or something whacked the tank and cracked it. Had I noticed it at Foretravel, I believe they would have admitted their error. Anyhow, those tanks are robust and without some kind of event like mine they are unlikely to leak.
jor

Re: Black tank leaking

Reply #12 – December 22, 2020, 01:13:43 pm

Thank you for the suggestions guys. Looks like it could be a few different things, which is good news, I guess. I'd hate to have to pull or replace the tank, so hopefully it's just a grommet or gasket.

Edit: I don't think we're overfilling the black tank, but I will do a visual inspection next time the sensor say's "full". How high should the BT level be relative to the bottom of the toilet hole?

Re: Black tank leaking

Reply #13 – December 22, 2020, 07:31:35 pm

"SeeLevel" is your friend for accuracy

Re: Black tank leaking

Reply #14 – December 24, 2020, 04:30:10 pm

I have a sea level tank monitoring system and I don't always get accurate black tank readings.
Sometimes when I have the fan on and I flush the toilet I can smell waste tank smell. I think it's due to my tank vent on the roof and I have a replacement I just haven't gotten up there and done it yet. You might want to look at that as well. Also when I replace my toilet I did not have a gasket that I noticed in the black tank. The PVC pipe that went down I had to shave off on all sides in order to get it to fit.a gasket would have made sense Sarah and I'm going to have to look into that next time.

Re: Black tank leaking

Reply #15 – December 24, 2020, 05:03:56 pm

Turn the fan off or close the lid on the toilet before you flush. Fan off is best.

Re: Black tank leaking

Reply #16 – December 24, 2020, 05:13:38 pm

Quote

Sometimes when I have the fan on and I flush the toilet I can smell waste tank smell. I think it's due to my tank vent on the roof

Like Michelle said, it's almost always a faulty air admittance valve. The roof vent is nothing more than a straight piece of pipe that Ts on top. Nothing to go wrong. You might consider replacing all of your air admittance valves with Studors and see what happens. 20 bucks at HomeDepot. I had to do that in two different rigs. In both cases, no more odor. I sympathize with you; I hate that smell. Good luck.
studor valve
jor

Re: Black tank leaking

Reply #17 – December 24, 2020, 05:18:57 pm

Quote from: jor – December 24, 2020, 05:13:38 pm

It's almost always a faulty air admittance valve. The roof vent is nothing more than a straight piece of pipe that Ts on top. Nothing to go wrong. You might consider replacing all of your air admittance valves with Studors and see what happens. 20 bucks at HomeDepot. I had to do that in two different rigs. In both cases, no more odor. I sympathize with you; I hate that smell. Good luck.
studor valve
jor

Good advice, especially if they are original or many years old. It doesn't explain the "puddle of undesirable material" in the wet bay, though.

The air admittance valves are basically one for every fixture, and the OP may find the ones for the shower and Splendide (if they have one) behind the washer/dryer, so a bit of a pain to get to.

Re: Black tank leaking

Reply #18 – December 24, 2020, 06:35:31 pm

Quote from: jor – December 24, 2020, 05:13:38 pm

The roof vent is nothing more than a straight piece of pipe that Ts on top. Nothing to go wrong.

That straight piece of pipe that Ts on top is actually a venture and needs forward motion to work well. Newer versions work when static with breeze in any direction drawing a low pressure on the black tank to draw air into the toilet when the valve is open.

Amazon.com: Lippert Components 389381 360 Siphon Roof Vent Cap - White (Gen...

Also mud Dobbers and wasps will build nests in them destroying there efficiency. My old T venture was 90% plugged
Scott

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Re: Black tank leaking

Reply #19 – December 25, 2020, 08:05:01 pm

Don't forget the anti siphon value on the black tank flush line. It's located behind the kitchen cabinets. Stupid design. When one hooks a hose to the black tank flush port, water travels thru the inside of the coach through this valve on it's way to the black tank. In our case when the black tank got over half full odors tended to drift through the pipe and escape into the kitchen (yuck)

. Nothing like pulling open a kitchen drawer and getting a whiff of black tank. Fix was to remove the valve and put in a piece of straight pipe. Another problem with this design was one could be flushing the black tank and the valve malfunction resulting in a flood inside the coach.

Re: Black tank leaking

Reply #20 – December 26, 2020, 04:18:54 pm

J R EX.
If you have the fan running above the toilet and you flush the toilet the fan now is pulling air inside the coach out to exhaust it, so makes sense for a second it will also draw some smell from toilet while the flange is open. Flush toilet close lid then use fan.
Johnh

Re: Black tank leaking

Reply #21 – December 28, 2020, 01:16:17 pm

I've already replaced all the arid mittens valves with the scooter ones except for the one that was with the washer dryer that I sealed off. It's not those they're all new. For me I'm pretty sure it is the vent on the roof. I can tell that it's not venting properly when I dump the black and gray tanks it just doesn't sound quite right hard to explain but I'll know after I replace it. the RV park where I'm at just doesn't have enough room between coaches to get up there and do it from the side and I prefer to do it that way. Also I'm pretty lazy these days. It's not a big enough annoyance to make me want to go up on the roof right now.

Re: Black tank leaking

Reply #22 – December 28, 2020, 06:51:59 pm

We were having black tank smell and I thought it was venting issue, but when I changed out the commode I could tell that the old one was not sealing good around the wax ring. On new commode I went with foam rubber gasket. No issue since the change
Chris

Re: Black tank leaking

Reply #23 – December 28, 2020, 06:52:44 pm

Wax ring in an RV toilet installation???

Kind of guaranteed failure.

Re: Black tank leaking

Reply #24 – December 28, 2020, 07:08:11 pm

Brett, it was there when I got coach-- didn't know until I changed commodes
Chris

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