Crack in holding tank

[Dennis and Carol]

Has anyone had any success with fixing a crack in a holding tank? Our gray tank has a small crack about half way up next to the discharge from the tank. No idea why it cracked as it is not in a location which would be stressed. I have a can of "Flex Seal" but have hesitated using it. Also, are the inlet connections to the tank glued. I would get a small amount of leakage if I would allow the water back up in the shower. All suggestions will be greatly appreciated.

[Ozz]

Yepper! The 'why' of the crack, is the rigid discharge pipe, you must install two rubber repair couplings in it so it can flex between the position of the empty tank and the full tank.
I will find my repair slideshow. There is a very good repair kit I found that works super. You have to follow the easy directions when you apply it. Black tank repair kit: Amazon
Kit:
http://www.amazon.com/Plasti-Mend-Plastic-Repair-Holding-Tank/dp/B003JC3UB2

Slide-show:
https://picasaweb.google.com/Jimsue13/20120113HoldingTankRepairs?authuser=0&feat=directl ink

[DQDick]

If you use the search function you'll find this thread: http://www.montanaowners.com/forums/...ms=tank,repair There are several answers for you there.

Ozz beat me. He's got a great answer or use some of the ideas on the thread.

[Exnavydiver]

After having all my tanks replaced over the last 5 yrs I understand why they kept cracking. All the discharge and fill fittings are plastic welded in place. As Oz said they need the repair flex couplings to absorb the flexing of the tanks and the vibrations of road time. I am on my 3rd black tank, the first was from a stupid, the second one was because the tank vibrated and broke the plastic weld around black tank fill pipe from the toilet. when they replaced the first tank they had to use a flex coupling on the pipe between the tank and dump valve but the still welded the top pipe to the tank and that is where it broke last time. The rubber repair flex couplings are not pretty but they and way better than the solid installations.

[GaryM]

I just had all three of my tanks replaced. My extended warranty covered the cost. The gray and black tanks were not installed properly and would slide about 2 to 3 inches to the front and back as we traveled with some liquid in them. This caused stress on the outlet fitting. I repaired the cracks with the tank repair kits but they are only temporary. Check to see if your tanks slide and get that problem fixed.

Gary

[1retired06]

I have successfully repaired holding tank cracks by applying a fiberglass patch followed by the eternabond tank tape, over the fiberglass, the kind with the metalic wrap on one side

[oldelmer1]

I blew out the seam in my black tank. I used the repair kit that OZZ recommended and it worked just fine.

[Pugtracker]

quote:Originally posted by Ozz

Yepper! The 'why' of the crack, is the rigid discharge pipe, you must install two rubber repair couplings in it so it can flex between the position of the empty tank and the full tank.
I will find my repair slideshow. There is a very good repair kit I found that works super. You have to follow the easy directions when you apply it. Black tank repair kit: Amazon
Kit:
http://www.amazon.com/Plasti-Mend-Plastic-Repair-Holding-Tank/dp/B003JC3UB2

Slide-show:
https://picasaweb.google.com/Jimsue13/20120113HoldingTankRepairs?authuser=0&feat=directl ink

do you have a pic of the two rubber repair couplings mod

[Ozz]

No, I didn;t take pictures, just put one close to the tank, under the black bottom cover, and downstream a couple of feet.

[Pugtracker]

quote:Originally posted by Ozz

No, I didn;t take pictures, just put one close to the tank, under the black bottom cover, and downstream a couple of feet.

Thanks,