Holding tank leak

[PitMan51]

I have leak in my holding tank. There appears to be crack in the weld where the 3 pipe is attached to the tank. Luckily it’s at top, so if I empty the the tank every few days, it doesn’t leak. I noticed all the other fittings are silicone in. I could simply caulk it, but I’m afraid if it that fails, it could be real pain to re-weld. Does anyone have any experience in this repair? We’re currently on San Luis Island Texas (between Galveston and Freeport).



Bill and Sonia
09 40MDTS

[Old Scout]

….didn't realize WRV welded the top entry pipe [from the toilet?]... the 3" soil pipe on my 2003 is caulked, as are most of the early coaches I've seen. Accordingly, its not really "sealed" so caulking the top of the tank now is probably not a biggie....other posts on this issue, suggest welding is about the only way to repair these tanks due to their high petroleum-based composition....

[PitMan51]

It’s the 3” at the bottom that’s leaking.








Bill Sonia
09 40MDTS

[Barbaraok]

Originally Posted by PitMan51

It’s the 3” at the bottom that’s leaking.


Bill Sonia
09 40MDTS

In your original post you said

Luckily it’s at top, so if I empty the the tank every few days, it doesn’t leak.

So some confusion.

[Old Scout]

...I guess what you are saying its leaking at the top of the 3" pipe, that is connected at the bottom of the black tank?????? my original post remains true, welding is about the only sure way to fix a leak on these tanks....

[Barbaraok]

Or is the the bottom of the 3" pipe just before the tank?

[Quiltlady]

Had a similar problem. Cleaned cracked area with file and abrasive paper. Applied JB weld with carbon fiber imbedded in JB weld material. Make sure the material has a smooth concave shape and adheres to the tank and pipe. Critical item was to make sure the supports are in place between the 3” pipe and the floor. Should be two supports, one near each valve.

[PitMan51]

We met a couple on the beach yesterday that retired from the RV repair business. They said to use the same repair method you are suggested.







Bill and Sonia
09 40MDTS

[PitMan51]

Just a quick follow up on my solution. I went to the JB weld website and they said their product will not work on HDPP. Back to YouTube. There were several videos on repairing gas tanks (HDPP) using a soldering iron - easier to use than a hot air torch. I didn’t have one with me so I bought a iron designed to be used on plastic - lower temperature. The kit came with “welding” rods and SS mesh. I melted the crack together with the iron and then bedded the mesh in melted rod over the crack. It only took about 10 minutes - 5 of that waiting for the iron to heat up. Then I added better support for the plumbing.

The original problem was probably cause by very little support under the 3” pipe.

Thank for the help on solving my problem.

The kit can also be used to repair broken tabs on our head light assembly



Bill and Sonia
09 40MDTS

[Hayduke]

Originally Posted by PitMan51

Just a quick follow up on my solution. I went to the JB weld website and they said their product will not work on HDPP. Back to YouTube. There were several videos on repairing gas tanks (HDPP) using a soldering iron - easier to use than a hot air torch. I didn’t have one with me so I bought a iron designed to be used on plastic - lower temperature. The kit came with “welding” rods and SS mesh. I melted the crack together with the iron and then bedded the mesh in melted rod over the crack. It only took about 10 minutes - 5 of that waiting for the iron to heat up. Then I added better support for the plumbing.

The original problem was probably cause by very little support under the 3” pipe.

Thank for the help on solving my problem.

The kit can also be used to repair broken tabs on our head light assembly



Bill and Sonia
09 40MDTS

Grats on making the repair

thanks for reporting back too.

That sounds like a very effective repair. Stronger than before!
Where did you find the plastic repair kit with the low temp iron?

[PitMan51]

Where else - Amazon!