leaking black water tank

omphoto · August 2020

I have a 2014 T@B 320 and after a week long state park visit, came home cleaned and sanitized the black water tank. A couple of days later a plate sized water leak was discovered coming from the exit pipe of the tank. I communicated with nuCamp about a schematic to help with the repair but apparently one does not exist. I did hear back quickly so I appreciate that part. There was some uncertainty from the tech people about how the pipe was fitted to the tank. If it was a spin on (their words) just the pipe could be replaced but if it was glued onto the tank, it would require a tank replacement along with the pipe. This would make it much more expensive to repair. Does anyone know how this pipe is attached to the tank for this model year? I would have thought nuCamp would have known but they did not regarding this particular model, the 320 S. Please see the attached photo and I hoping that someone has the answer.

Image: https://us.v-cdn.net/5021717/uploads/editor/wj/4z5q9x30tdn8.jpg

Marceline · August 2020

@AldebaranJill do you know?

eeeckman · September 2020

I have the same problem. Another thread said the elbow is glued to an abs nipple on the bottom of the tank. I pried all the caulking away and am trying to remove the elbow but no luck so far. Local dealer wants 16 hours of labor to pull the tank from the inside and then determine how to fix.

4ncar · September 2020

Looks like a glued fitting to me.

ChanW · September 2020

Unless you're sure it's the black tank (ie: smell or some other telltale), you might want to look in the compartment that has your freshwater pump (behind the toilet).

Wedge your head in there, or a camera, with a light, and look down on the floor to make sure you haven't had a fresh water leak constantly dripping in there . There are a number of places where leaks are known to pop up in that area. (Keep a phone handy with you, so you can call someone if your head gets stuck in the hole)

Check your water pump connections, and check the fresh water intake connections on the outer wall for signs of leakage. Also, some people have had problems with pipe connections down in the bottom area of that compartment.

omphoto · September 2020

Here is my update on the problem and the repair.
After removing the strap that secured the elbow, I could see that it was loose and rotated with a little bit of twisting. I eventually worked it out with gentle twist and pulling. The other photo shows the white plastic (nylon or polyethelene) sleeve that comes out of the black tank. That was very securely attached to the tank, probably glued, and with a spongy neoprene like filler that was put in to stabilize and minimize movement of the components and keep out bugs and critters. As best as I could determine, the leak happened because that white looking substance on the elbow no longer had any properties to seal/adhere the elbow in the white sleeve, hence since I could easily twist and remove it as it wasn't doing it's job any more. My T@B is 6 years old(I'm the third owner) and we have been using it hard in the 2 years we've had it. The issue than became what to use to reattach everything. 3M Marine Sealant and Adhesive is a very aggressive product along with Loctite Marine Sealer/Adhesive( half the price of the 3M). Once these products set there is no way to undo it. I wanted something that would allow for a test of the leak but could with some effort allow removal to redo the repair. Finding something that was compatible with two very different plastics was a bit of a challenge but my local hardware recommended a neoprene sealant used on commercial/residential windows, so I bought the Master Seal NP1. It is a high end industrial grade sealant that is not considered an adhesive. It has a very high flexible quality when dry and is a superior grade product. I applied a decent sized bead around part of the elbow that has a ridge that stops the elbow from sliding to far into the sleeve. You can see where the original white stuff kind really didn't make it to that point. After sliding it into the sleeve whatever oozed out I used my gloved finger to smear it around the seam. I waited 24 hrs for it to skin over than tested it and saw no leaking. Next was what to use to fill the void space around the sleeve. Again it had to be flexible and water resistant. I settled on Total Pond "Water Fall Foam Sealant". It comes in a spray can like the yellow stuff people use around electric outlets and plumbing to keep air from entering your house. This was another neoprene based product. The only issue is that it has to held upside down when using which made it difficult to apply to the void space around the sleeve. Eventually I got enough in to finish the job. I reattached the metal strap and made sure it was snug against the elbow to minimize any movement from traveling and dumping the tank. So far the repair appears to be good, I'll update if necessary but I feel confident this will work. The bonus is that I saved a lot of money doing it myself. If the leak would have been around the sleeve where it is attached to the tank, it would have required pulling the toilet and either pulling the tank out or using an epoxy sealer to eliminate the leak, again another costly repair if you can't do it yourself.

Image: https://us.v-cdn.net/5021717/uploads/editor/rp/ey03bbmv0x77.jpg

Image: https://us.v-cdn.net/5021717/uploads/editor/uu/6d1y80ndpk9b.jpg

Sharon_is_SAM · September 2020

Wow, well done @omphoto! We don’t see too many black tank plumbing repair jobs here. Thanks for documenting your repair.

ChanW · September 2020

Thanks for this. If ours is installed the same way, I imagine I'll need to deal with it sometime in the future. And I'm sure I wouldn't have thought I could 'simply pull it out'! What a strange way to connect that fitting (unless easy removal and replacement was the intent - which Nucamp has clearly 'forgotten'!)
And thanks for writing it up so fully.

4ncar · September 2020

Ya, brave task. I am not one to shy away from certain tasks, but laying under the black tank drain as you must have would be one thing I would really have to think twice about!!

I cant see where the fitting would be intentionally unglued; it would have leaked from the start. I think the glue failed over time and you were fortunate that the joint broke free cleanly. Good work, none the less!

eeeckman · October 2020

Thank you for this onfo!!! I had the same leak; but in my case, the sleeve was secure to the elbow but loose in the tank. I could swivel the elbow/sleeve but could not get it to come out. Maybe a matter of leverage. Pulled the toilet, marked the exit pipe/sleeve edges in the tank with a paint pen and could see the inner sleeve attached to the elbow move. Resecured the elbow to the T@B and coated the exit pipe and sleeve ends inside the tank with several layers of rubber sealant. Initial leak check is good, need to see how it holds up in the long run.

Jetman · September 2021

Omphoto,

I had same problem on my 2015 TAB 320S, followed your instructions explicitly and worked like a charm ( unusual install of a pipe drain into a pipe, no to the outside of the coupling). No more leaks an two trips under my belt.

Thanks a lot
jetman

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