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Grey tank leak at abs/pvc connection

March 13, 2022, 10:08:31 am

I've been replacing my seals and Valterra valves..  Got them all replaced and went to test for leaks. Figured out we had a leak at the connection at the abs/pvc. Probably due to disturbing it during the install of the valves.

So, took it all apart (again). I need to remove the abs from the tank.  It has plumbers putty (or whatever) plus the clamp. Question is, how do I get this connection apart.  Heat maybe? 

See pictures of where the leak is. https://www.foreforums.com/index.php?action=dlattach;sa=tmpattach;attach=post_tmp_8100_d962c599a0db3df3dd8f298167f415cb;topic=0

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Re: Grey tank leak at abs/pvc connection

Reply #1 – March 13, 2022, 10:24:05 am

The only way I've ever been able to completely fix something like that is to cut it off as close to the fitting as possible then redo with new fittings. You can try getting it really dry and going around fitting with epoxy. Would be worth a try but don't get any back to far on the tank pipe as you will still need enough to glue a new fitting on if this repair doesn't hold. Probably the incorrect glue was use when putting a pvc fitting on abs. The pvc is much harder than abs so a primer is needed to break down the hard shell on the pvc. If you can stick with abs throughout, less problems. It's not as easy to find but dedicated plumbing stores have it, big box not so much.
Larry

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Re: Grey tank leak at abs/pvc connection

Reply #2 – March 13, 2022, 10:36:43 am

To separate those two pieces and keep them intact is unlikely.  If the primary objective is to preserve the ABS, I would cut through the PVC piece horizontally on the exposed side.  It cuts pretty easy with a hand saw.  You might get lucky and shake the piece loose.  If not, cut gently through the flange of the PVC where it is attached to the ABS, leaving the abs pipe intact.  Then insert a screwdriver blade into the slot and twist.  I have been able to separate a lot of pipes this way.  The cement has very little strength when pulled away from (rather than across) the other surface.

Good luck!

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Re: Grey tank leak at abs/pvc connection

Reply #3 – March 13, 2022, 11:05:34 am

Thanks for the reply Larry. I agree going back with new fittings. My thoughts were to remove fitting from tank. Then rebuild with new fittings. Was having a problem removing the fitting that is stuck into the tank and sealed with plumbers putty and a hose clamp. The putty or whatever the goo is, is a worthy adversary. Also not sure where to get a new fitting to go into the tank, if I need one.  Have a trip planned leaving this Saturday.  This photo was borrowed from someone else. https://www.foreforums.com/index.php?action=dlattach;sa=tmpattach;attach=post_tmp_8100_c7866571c1bd952cafcd7e7ed69ee46f;topic=44188

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Re: Grey tank leak at abs/pvc connection

Reply #4 – March 13, 2022, 11:23:17 am

If that's just plumbers putty and a clamp on the pipe in tank then should come out easy. If it's not and doesn't move easily be careful you sure don't want to damage the tank flange or you will have opened that can of worms that I seem to stock a lot of. Slow and easy is the rule don't force anything.
Larry

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Re: Grey tank leak at abs/pvc connection

Reply #5 – March 13, 2022, 11:52:51 am

I got the fitting off the tank. Pointed an electric heater at it for about an hour. It softened what appears to be plumbers putty enough to coerce it off. https://www.foreforums.com/index.php?action=dlattach;sa=tmpattach;attach=post_tmp_8100_b66bde72d4efee502037449e8c35ffef;topic=44188. Now to figure out what to do from here.

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Re: Grey tank leak at abs/pvc connection

Reply #6 – March 13, 2022, 12:09:32 pm

ABS and PVC are not compatible to glue so stick with ABS and if you have to use both
then clamp them together. They make clamps for that. Some of the parts you may be need
to be gotten through and RV shop.

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Re: Grey tank leak at abs/pvc connection

Reply #7 – March 13, 2022, 01:45:35 pm

Agree, just start over with everything new and do not mix plastics. Glad you got it off now the rest should be straight forward.
Larry

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Re: Grey tank leak at abs/pvc connection

Reply #8 – March 13, 2022, 02:44:14 pm

Tom,

You will find that the parts you need to make up the spot for the level transmitter in ABS isn't available which is why they (FT) used the PVC fittings.  The problem is they didn't use green transition glue that is made for ABS to PVC.  This glue is generally on the bottom shelf in the PVC area of most home improvement stores. The Oatey brand has worked best for me but that is just a suggestion.

Mike

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Reply #9 – March 13, 2022, 03:16:16 pm

Thanks I was suspect of the pvc to abs bond. I am going to make a " temporary repair " with epoxy and a rubber boot. When I do a more permenant repair. I will do away with the pvc fittings and those tank sensors. I will install a sea level system. I do not have time to procure all the necessary parts right now, to do what I want.  Tom

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Re: Grey tank leak at abs/pvc connection

Reply #10 – March 13, 2022, 07:39:08 pm

I have it all put back together. I sanded and cleaned area, then I put JB weld marine weld on (cures in 1 hour).  Next I put 3M 4200 on and covered with a rubber boot while still wet. I told Michelle I would crap 10 tons of bricks if this leaks from this spot again. I really hope it doesn't leak.    Tom

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Re: Grey tank leak at abs/pvc connection

Reply #11 – March 14, 2022, 09:50:21 am

I'm late to this party but I have used Fernco connectors a lot for server line repairs. The seal easily and can be removed later. Some big box stores carry them but you can order pretty much anything you need. Here is just one example:

Search: 10 results found for "fernco" | Max Warehouse

Have fun! LOL!

TOM

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Re: Grey tank leak at abs/pvc connection

Reply #12 – March 14, 2022, 10:57:00 am

So I keep thinking why did it started to leak assuming it was assembled correct. The puddy on the outside doesn't make sense to me. I would guess the leak was caused by freeze damage, not disturbing it, but dont know. There is some pressure with a full tank and bumps during travel. Guess what I'm trying to say is make sure it's empty if subject to freezing. I always attempt to keep my boat from freezing for the same reason. They do make toilet flange cutting tools that would work to remove the PVC from the ABS  but I would just replace them all.
Scott

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Reply #13 – March 14, 2022, 11:25:11 am

I make a point of pouring about a half gallon of RV antifreeze into each of the holding tanks and then draining the anti freeze out and leaving the valves open during traverse to storage and the winter.
Seems every spring after I drive the coach out of storage and stop on the inclined road the DW says to me:"Look at something running out on to the road under the coach." And I always explain that the coach is now sitting facing uphill on the side road so there was probably some liquid that had been still in the tank.
Never had any problems with our valves.

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Re: Grey tank leak at abs/pvc connection

Reply #14 – March 14, 2022, 11:54:56 am

When I said use clamps I meant the Fernco connectors, which I have used a lot but I
never knew what they were called.

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Re: Grey tank leak at abs/pvc connection

Reply #15 – March 14, 2022, 02:40:00 pm

Yes I have questioned why it would start leaking at that joint after all these many years.  It has been stored in a heated shop at my house and monitored. I know it hasn't been subject to freezing this winter.  After I removed the plumbing  from the tank, I could really get a good look at it. It was glued on a little crooked but seemed well bonded. I could not see why it would leak. I also did not handle it rough when replacing the waste valves. I was completely shocked that it started leaking where it did because in my mind it hasn't leaked since 2004 and 100,000 miles. I am not particularly happy that I did a patch job repair, but I am confident that it is highly unlikely to leak from that spot.

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