Holding Tank Crack

It seems every trip has a new problem and our latest was no exception. I have a 10" crack in the bottom center of the ridge detent in our holding tank. There was no apparent leak or problem on our first two trips this summer so I don't suspect it is a freeze problem. However, it is at the greatest flex point of the tank and I suspect with no external support the flexing of the tank caused the crack. Any thoughts or others who have had a problem?

In any case, preliminary estimate is $700 for a new tank (installed). I haven't found out yet how much is labor and how much for the tank and will be looking at doing it myself - I haven't been impressed with the workmanship I have seen on a couple previous repairs at the dealership that I had to then redo. Anybody changed out the tank? I have tried calling TM service but got voice mail and last time it took 3 days for a return call so this forum has proved far more useful.

My initial plan is to drill a tiny hole at each end of the crack to hopefully stop the spread and then fill the entire area/crack with a plastic weld epoxy. I have serious doubts that it will be a long term fix but may get me by until I get a new tank (apparently at least a couple weeks). Another concern is the epoxy I have found will not work on polyethylene or polypropylene plastic and I don't don't know what the tank is made of (another unanswered question for TM).

Just repaired some exploding tire damage to my holding tank again! The tank takes the glue for the black pvc pipe. You can also make filler with same pipe and acetone by letting some pieces of pipe in a can soak together. Epoxy and fibre glass will stick if surface is clean.

[Bill]

You can also look for posts by BobRederick in the plumbing forum about a year ago. He managed to do an ultrasonic (?) weld on a broken tank using a cheap tool from Harbor Freight, as I recall. But the thread, which was quite long, had a lot of good info in it.

Bill

[Wavery]

Pics would be helpful.

They sell ABS plastic in sheets. If the tank is ABS (black PVC pipe), you may be able to repair that tank to be stronger than a new one.

The "Glue" that you get for ABS pipes is really not a glue at all. It actually melts the surface of the 2 pieces being joined and when the melted plastic hardens, it becomes one piece. It is actually better than a weld because you can overlap and have a much larger contact surface than a weld.

If it were me, I would clean the surface thoroughly with TSP. Then I'd rough it up with 100G sand paper (be sure to clean it first so that you don't sand oil into the surface). Cut a piece of ABS sheeting to fit over the crack and overlap about 1" on either side. Check to see that it fits nicely, then put a coat of the ABS glue on both pieces, (a 2 person job, one on each piece). Immediately apply the repair patch to the tank and hold it in place for about 30 seconds.

If the crack is on a bend, you can heat and bend the repair patch to match.

It would be best if you removed the tank but I understand that's not an easy task. It can be done with the tank in place.

Thanks for the info... I'll give it another look. The crack is in the "valley" of the longest reinforcement ridge on the bottom of the tank so abs fabric might work as reinforcement after I get the crack glued. There is no gap associated with the crack until I push up on the bottom of the tank so I may be able to force the crack open, fill it with abs cement and then reinforce it later. Again, thanks for the info.

[Wavery]

Originally Posted by Fdxflyer

Thanks for the info... I'll give it another look. The crack is in the "valley" of the longest reinforcement ridge on the bottom of the tank so abs fabric might work as reinforcement after I get the crack glued. There is no gap associated with the crack until I push up on the bottom of the tank so I may be able to force the crack open, fill it with abs cement and then reinforce it later. Again, thanks for the info.

I wouldn't bother "Gluing" ABS. It won't hold over time. That stuff must be chemically (or heat) welded. If you put glue on it, you may find yourself having to scrape it off and using the ABS patch before very long. ABS glue will not adhere to glue, it will ONLY work on ABS.

That tank has a lot of flex in it when you're driving down the road.

exactly wayne. abs and pvc glue are not inter-compatible either.