Fresh water leaking thru coroplast - power fill with frozen overflow pipe?

[steve&renee]

That "hole" is in the center of the tank to add a little rigidity to the top and bottom of the tank.

Brian

My story has taken now left unusual and perplexing and entered the land of wacko.

I bought Flex Seal Tape (actually a Gorilla Tape knockoff) this morning and pealed the freshwater tank heating pad off. To my surprise, the heating pad was covering a second rigidity "hole" manufactured into the tank from bottom to top. Surprised to say the least. I doubt if the heating pad would do much good warming up a hole.

Anyway, I examined the tank surface where the pad had been attached and all around it. No cracks, no holes. This got me pretty flustered, because I started thinking the leak was coming from the area between the tank and one of the beams that support the tank -- an area totally inaccessible to seal-tape. If there was a leak between the tank and the beam, it might have flowed across the bottom surface of the tank to the heating pad and merely appeared to be coming from under the pad. If that was the case and the leak was on the bottom of the tank and inaccessible to patching, I'd probably have to abandon living in the RV.

I wasn't able to refill the freshwater tank with water (and attempt to identify the source of the leak) until this afternoon -- because the builder was borrowing my water hose.

Finally got access to the water hose and started filling the tank. We'd used some water since I last saw the leak, so it took several minutes of filling the tank back up before the leak started up again.

Believe it or not, the leak originated from the near the top of the rigidity-hole that was covered by the heating pad. Near the top of the hole! And that's good news (in a twisted sort of way) -- because it means I can fill the freshwater tank more than 3/4 full before leaking. I'll have to refill the tank more often to stay hydrated, but I'm not out of bullets. Oh, lucky me.

I haven't isolated the actual leaking-breach yet. It was getting dark and I didn't have a flashlight. Reaching into the hole, it feels like the top of the hole is covered with felt or tar-paper. It's loose, not sealed. Just guessing, but I'm think the hole is directly under the RV floor positioned between the island and the cook-top counter. In other words, completely inaccessible.

As for addressing the leak, the only thing I can think to do at this point is get a mirror-on-a-stick and try to examine the top of the hole from the bottom side in hopes of locating the breach. Doesn't sound very promising.

Suggestions? Cate&Rob ??

-Steve

[Country Campers]

steve&renee

You are this far into it so you might just be further off to just replace the tank. The only connections are at the end where the drain is. Maybe a call to GD to see if they could send you a tank for replacement. I am not sure if you could by one from a RV supply store that would be an exact match. You could cover the bottom of your tank with some blue board insulation, 1" thick rigid foam and just use the 3/4 tank as you need and then work on this in the warmer weather next year. If you could measure your tank, length width and height , i could try to help you find one. I also would wonder if the flex seal spray would seal the leak up in the hole.

Brian

[Cate&Rob]

steve&renee amp;
Hi Steve,

Trying to patch this tank while it is in place is going to be a frustrating exercise and you will always be wondering when the leak is going to open up again and dump water into the underbelly. I would follow Brian's advice and remove the tank for repair or replacement. From the Grand Design parts look-up and your description, I think your tank is probably Grand Design PN 320044 which ties to the supplier drawing attached (from the GD parts list so OK to post here). Check the dimensions of your tank before ordering one of these . . . yours could be different.

In the interim (since you are not travelling) could you rig up another source of water? Something like a rain barrel with an immersion heater (available from farm supply places) and a heated supply hose. Connect this water supply with water panel settings for antifreeze/sanitize and your pump should be able to draw from this source.

Rob

[Yoda]

I did discover that the horizontal overflow pipe and valve I added to the vertical OEM overflow pipe was frozen solid. I cut the horizontal section off. The vertical section of the pipe was pretty free of ice. I'll heat it up with a hair dryer before re-filling the freshwater tank. (I added a horizontal pipe section and valve to the overflow to prevent losing freshwater while driving. The horizontal section was to be able to reach the valve without crawling under the trailer.)

So for now, I'm at a loss in understanding the source of the leak. My plan is to re-fill the tank while watching for leaking later this afternoon. I'll report the results when they're available.

There was a mysterious manufactured hole in the tank that I didn't understand. The inside of the hole was dry to the touch. Here are some pics:



If anybody has an idea about this hole, I'd like to hear it.
n
-Steve

Steve - sorry for your troubles here. I am going to guess by looking at the above photo that with the vent pipe frozen, the tank became pressurized and a seam split around the top of one of the baffle holes. Also it may be the camera angle, but the support beams look bowed.. Are the beams in the picture the L channels the tank sit son, or just flat strapping? I am no expert, but the only way to really know is drop the tank to find the split. I believe the supporting structure is just bolted to the frame too, so should be easy to undo,

Hope this helps

Keith

[steve&renee]

Steve - sorry for your troubles here. I am going to guess by looking at the above photo that with the vent pipe frozen, the tank became pressurized and a seam split around the top of one of the baffle holes. Also it may be the camera angle, but the support beams look bowed.. Are the beams in the picture the L channels the tank sit son, or just flat strapping? I am no expert, but the only way to really know is drop the tank to find the split. I believe the supporting structure is just bolted to the frame too, so should be easy to undo,

Hope this helps

Keith

Yes, the beams looked bowed to me, too. They are steel enclosed box-beams,, maybe 1/4 - 3/8" thick and 2 1/2 - 3" wide. Not enough support for an 81 gallon tank in my opinion.

Just got back from the store with a lighted, telescoping inspection mirror. I discovered a lateral crack/fissure at the top the rigidity-cylinder with 3 or 4 holes in it. The other cylinder has no such crack/fissure.

Here's some bad pics (camera won't focus that close):




Pretty sure the tank is made of polyethylene. My plan to buy some time is to buy a tube of sealant/adhesive, patch the holes and fissure, then seal it over with Flex Tape. Any suggestions on a sealant would be appreciated.

I've scheduled a service appointment with my dealer March 10. Hope the dealer will be able to drop the tank and weld it back together -- or just replace the whole thing.

-Steve

[TedS]

The tank material is polyethylene. I watched a video in which epoxy and glass matte was used to patch a tank. Kind of a messy process working upside-down but it appeared to make a good patch. The tank surface must be roughened to help anything stick.

[Yoda]

Yes, the beams looked bowed to me, too. They are steel enclosed box-beams,, maybe 1/4 - 3/8" thick and 2 1/2 - 3" wide. Not enough support for an 81 gallon tank in my opinion.

Just got back from the store with a lighted, telescoping inspection mirror. I discovered a lateral crack/fissure at the top the rigidity-cylinder with 3 or 4 holes in it. The other cylinder has no such crack/fissure.

Here's some bad pics (camera won't focus that close):




Pretty sure the tank is made of polyethylene. My plan to buy some time is to buy a tube of sealant/adhesive, patch the holes and fissure, then seal it over with Flex Tape. Any suggestions on a sealant would be appreciated.

I've scheduled a service appointment with my dealer March 10. Hope the dealer will be able to drop the tank and weld it back together -- or just replace the whole thing.

-Steve

Yep withe vent plunged by ice it pressurized and blew the seam - probably bowed the beams too. When the dealer drops the tank have then install reversed - bow upwards. The tank being pressurized probably bowed them. The are strong enough to support the tank normally.

As for sealant, check with the dealer first - sealant could make it difficult to Weld if that is what they are going to do. Depending on thier labor rates it may be cheaper to drop and just replace with a new one. That's what I would do - there may be other seams compromised that have not cracked yet.

And while it is down you can fix the overflow to the twin down tube design to prevent siphoning (and your ice issue). Rob Cate&Rob designed it and GD is using it now on new production.

Good luck

BTW - You have the honor of being the first to burst a water tank here that I know of - then again not much of an honor?

Good luck and Happy Holidays
Keith

[TedS]

Reversed installation would put the drain depression in the tank upwards.

[howson]

Pretty sure the tank is made of polyethylene. My plan to buy some time is to buy a tube of sealant/adhesive, patch the holes and fissure, then seal it over with Flex Tape. Any suggestions on a sealant would be appreciated.

Steve,
We were taught at school that nothing permanently sticks to poly--a permanent repair requires plastic welding. The school didn't come down off a mountain with tablets of wisdom on all things RV...so perhaps there is a way other than plastic welding, just know that you could spend a lot of time (with equal parts frustration) and still end up changing the tank.

Howard

[steve&renee]

Steve,
We were taught at school that nothing permanently sticks to poly--a permanent repair requires plastic welding. The school didn't come down off a mountain with tablets of wisdom on all things RV...so perhaps there is a way other than plastic welding, just know that you could spend a lot of time (with equal parts frustration) and still end up changing the tank.

Howard

I get that nothing sticks permanently to polyethylene. I'm just hoping to mask (get it?) the problem until we move out of the RV in January.

The best sealant/adhesive is supposed to be Sikaflex 292i adhesive for marine applications, but I wasn't able to find a viable source. Ended up buying 3M 5200 sealant, which is stocked at the local marine supply house. Once the 5200 cures, I'll apply some Gorilla flex tape on top. Like I said, just hoping this provides me with a temporary fix that lets me fill the freshwater tank more than 3/4 full.

I agree with Yoda . The tank should be replaced, because there may be other seams that are compromised. I've got a service appointment at my dealer March 10, 2022. I'll be letting him know I need to order a new tank, drop the old one, and install the new one.

-Steve

[Yoda]

Reversed installation would put the drain depression in the tank upwards.

I was talking about the bowed beams, not the tank

[steve&renee]

I was talking about the bowed beams, not the tank

I knew that. Minds like ours think alike. Not great minds, just minds like ours 😁

[Cate&Rob]

steve&renee amp;

3M 5200 is a good choice. I have used it in marine applications and the bond is amazing but still retaining some flex which will be necessary as the weight of water in the tank changes it’s shape slightly. Replacing the tank should be the longer term plan.

Rob

[Yoda]

I knew that. Minds like ours think alike. Not great minds, just minds like ours 😁

I don't know Steve I think I have a GREAT mind. I model myself after Pinky and the Brain.....and it's the Brain, not Pinky

To bad that it's not on anymore.

What's great about this place is the mind melding that goes on - some excellent solutions have come out of folks thinking together.

Merry Christmas and the best for the New Year
Keith