My black tank ruptured today.

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Rene T

Rene T

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Joined
May 20, 2011
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22,430
Location
Farmington NH
Yes you read it correctly. I was flushing it with the black tank drain closed. I've been doing it this way for years. I don't know what happened here but after about 10 minutes which is 10 minutes sooner than I normally flush for, I heard a bang and water started pouring out from under the rig. I just can't believe the tank broke because it was somehow pressurized. It should have vented through the roof vent. The vent was checked for obstructions last year with a garden hose.  I dropped some of the belly and I was able to see most of the bottom, sides, back wall and front wall.
I didn't see any indication of where the water came from. I'm letting it dry out a little tonight. Tomorrow I plan on dropping a little bit more of the belly and try to get a peek at the top using a mirror. I'm hoping the crack is on top. If it is, I'm hoping I can go a couple of days and then flush.
If this works out for the rest of my winter in FL, (6 more weeks or so) I'm hoping it will last till we get home and that the crack doesn't get bigger. Then when I get home,  I plan on dropping the tank and make the necessary repairs if it's salvageable. 
I've got two questions:

1)  Will fiberglass stick to ABS?

2)  I'm told, I may be able to get it welded. What type of business would do that type of work and how would I find them?
 
Wow, yeah I'm sorry to hear about this too Rene. Odd indeed. A lot of RV holding tanks, including ours, are made of Polyethylene (PE) not ABS. There are some newer epoxies that will adhere to PE surfaces, but they aren't suitable for all PE repairs. They can be used to glue small cracks that aren't exposed to flexing stresses, and you can use them to adhere small things to a PE surface, but welding is the best method of repairing PE surfaces that have to flex a lot, carry a significant load, or the damaged area is relatively large.

Kev
 
Interesting. I've never heard of that happening before. Was the tank actually full of liquid, or maybe the "bang" you heard was the sudden release of air and liquid? Still points to a venting problem. But my thinking is maybe the seal of the vent stack or toilet connection into the tank ruptured if the tank was completely full of liquid? Meaning the tank itself might be OK.

Just a thought. Keep us informed.
 
West Systems "G-Flex" epoxy will adhere to both plastic and fiberglass and metals and almost every thing else.
Get on the phone with them, and they will walk you through the process.

It used to be very hard to repair plastic, and the only good way was plastic welding, but now it is simple with G-Flex epoxy.  I have used it to fix leaks between PVC and brass fittings

jack L
 
JB Underwater Weld does magic!

I just used it to repair my leaky hot water tank last month. Not a drip since then!

My friend was so intrigued that when he discovered his fresh water tank was leaking under his rig, he used up the rest of my JB Underwater weld for his fresh tank. Not a drip since then.

All this for about $5 from Amazon.
 
I only call the tank ABS because it's black. It could very well be a PE tank as Kevin mentioned. The funny thing is that the same thing happened last year but that one was covered by a extended warrantee we had purchased when we bought the rig used. Last year, I was flushing it and was inadvertently sidetracked and walk away and it also ruptured or something let go . I never saw the old tank to see the crack. The dealer had already thrown it away. I can see the inlet pipe joint, the outlet pipe joint and the vent pipe joint. They all are OK.
The area where it' leaking is in the same general area as last years tank leak.  On top and on the FWD end of the tank. I'm starting to wonder if maybe the manufacturer of the tank, when designing it, put in a weak point which would let go in case of the tank being pressurized. If that's NOT the case, now I'm wondering why the water just didn't go up the vent stack UNLESS the RV manufacturer installed a air admittance valve or some type of check valve which will allow air to come down the vent stack when dumping but will close to stop water or gases from going up the pipe.
I know the tank manufactures name so I may call them tomorrow and also Keystone to see if they have a piping schematic they could give me.

The ground under the belly is still pretty wet for me to lay under there. When it dries out a little more, I'm going to see if I can see anything on top using a mirror. The top is almost up against the bottom side of the floor so that may be fruitless. I'll let you know if I see anything. 
Thanks for all the suggestions so far.
 
I had a similar incident. I overfilled my water tank and its expansion blew it out of its metal mounts. BOOM! The leak was found at the connecting pipe and was easier to fix than than bending the mounts back into shape to securely hold the tank again.
 
Rene T said:
Last year, I was flushing it and was inadvertently sidetracked and walk away and it also ruptured or something let go . I never saw the old tank to see the crack. The dealer had already thrown it away. I can see the inlet pipe joint, the outlet pipe joint and the vent pipe joint. They all are OK.
The area where it' leaking is in the same general area as last years tank leak.
Click to expand...

At some point I would be investigating the tank to see if the tank was replaced or repaired.
 
First time I hooked up the tank flush feature on my new coach I got water running out from under the black tank, not through the drain.  I suspect that the flush system piping has cracked due to inproper winterization.  I've had the black tank full all the way into the pipe below the toilet flush valve and no leakage, so I know it's not the tank.

Could the piping for your flush system have let go?
 
Update: I was able to get under the rig and tried to get a look. I found that the tank top is flat and it's right up against the bottom of the floor. What I did find was that the way the tank is built is like this. The sides go up and then they turn out 90 degrees to form a 1 1/2" flange. Then the top is merely a piece of flat material epoxied somehow to the side flange. I'm thinking the flanges came apart in one spot. It may be just a matter of dropping the tank, removing the top, and regluing it to the tank.  I won't do that till I get home in April.
 
And maybe support the sides?

If that design failed twice just from overfilling (no pressure in the tank), then it has to be the weight of the water causing the sides to bulge and pulling on the flanges, tearing the lid epoxy.  The water couldn't have pushed up on the lid to tear it apart because if that was the case, you should have had water shooting out the vent.

Just a thought...
 
FelineSpirits said:
And maybe support the sides?

If that design failed twice just from overfilling (no pressure in the tank), then it has to be the weight of the water causing the sides to bulge and pulling on the flanges, tearing the lid epoxy.  The water couldn't have pushed up on the lid to tear it apart because if that was the case, you should have had water shooting out the vent.

Just a thought...
Click to expand...

The tank is supported by the long sides. I have two other tanks the same model and haven't had issues with them. When I get the tank down, I'm going to rig up something on the end of the vent pipe and pressurize it and see if there isn't a restriction in the line like maybe a check valve.  I may also call the RV manufacturer tomorrow,.
 
denmarc said:
Sounds like you got your work cut out for ya. Hope you have good luck with the rest of your journey until you make it home.
Click to expand...

Thanks Mark. I'm going to try dumping tomorrow so see if I get any water leakage from the tank. If the flange is the culprit, I'm hoping I'll be OK.
 
Rene T said:
The funny thing is that the same thing happened last year but that one was covered by a extended warrantee we had purchased when we bought the rig used. Last year, I was flushing it and was inadvertently sidetracked and walk away and it also ruptured or something let go .
Click to expand...

If your arm hurts when you raise it over your head, don't raise your arm over your head.

Your tank flusher has now ruined two sewer tanks, I'd throw it away instead of wondering when the third will let go.
 
Just wondering why you are taking such seemingly extreme measures to flush your tank?

Isn't just adding a few gallons of water and using a jet nozzle on the end of a wand enough?

We have no odors and our tank has never been subjected to pressure flushing. You obviously have a reason for doing so, just curious what it is.
 
Tom Hoffman said:
Just wondering why you are taking such seemingly extreme measures to flush your tank?

Isn't just adding a few gallons of water and using a jet nozzle on the end of a wand enough?

We have no odors and our tank has never been subjected to pressure flushing. You obviously have a reason for doing so, just curious what it is.
Click to expand...

I just always felt I would get a better flush by partially filling the tank with fresh water. When I'm doing the dumping, I do this procedure 2 or 3 times and you'd be surprised how much crap still comes out of the tank.

I still don't see how the tank would get pressurized. The nozzle has about 8 small holes in it which are probably 1/16" in diameter. Not much water going into the tank and then there's the vent. It still should have gone up the vent.
 
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