Cracked Water Tank

[campdaddy]

Just pulled the PU out from winter storage and while flushing the water tank found that the fresh water tank has a leak in it.  It wasn't caused by freezing as the tank was stored dry. Actually, we camped late last season and ran out of water kind of too soon so it may have been something that happen last year. It's not a line type of crack that needs to be stop drilled. It's more like it was hit by something that didn't brake all the way through but just kind of crazed it in one spot, that now leaks. Anyway, does anybody have any suggestions as to what might patch it.  I think the tank is polypropelene? I don't know if RTV or some kind of Epoxy would be better. Any suggestions? Thanks in advance

[wavery]

Just pulled the PU out from winter storage and while flushing the water tank found that the fresh water tank has a leak in it.  It wasn't caused by freezing as the tank was stored dry. Actually, we camped late last season and ran out of water kind of too soon so it may have been something that happen last year. It's not a line type of crack that needs to be stop drilled. It's more like it was hit by something that didn't brake all the way through but just kind of crazed it in one spot, that now leaks. Anyway, does anybody have any suggestions as to what might patch it.  I think the tank is polypropelene? I don't know if RTV or some kind of Epoxy would be better. Any suggestions? Thanks in advance

Most of those tanks are made of Polyethylene. Polyethylene cannot be glued. It must be welded. If it is Polyethylene you may want to get yourself a piece of Polyethylene. Cut the piece round, about 1/2" larger than the crack.  Take the tank and Polyethylene piece to a local body shop and ask them to weld it over the broken area.

Polyethylene is the material that they make car body parts out of. Almost all body shops have those welders. However, if they want a lot of $ to do it, you can buy your own welder here:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=41592
They are fairly easy to use. You just have to make sure that you get Polyethylene welding rod. I'm not sure that it comes with that welder.

There are some glues on the market that claim to work on Polyethylene. I have tried them all and I have had no success. I assume that your crack is on the bottom of the tank. There is a lot of pressure there when the tank is full.

[oldmoose]

I had a crack in mine and I got some of the rubber roof patches. They are self adheive and mine is holding well. They are fairly inexpensive and easier than patching with fiberglass.Moose

[campdaddy]

Thanks for the info guys. I'll go back under it this weekend and see if I can fix it without pulling it out.

[wavery]

I had a crack in mine and I got some of the rubber roof patches. They are self adheive and mine is holding well. They are fairly inexpensive and easier than patching with fiberglass.Moose

It's funny that you should say that.

We are roofing our apartment building right now. They are using this peel & stick roofing paper. It's the stickiest stuff I've ever seen. I have a polyethylene tank with a crack in it. I'll see if this stuff will stick to it.

[oldmoose]

I got my patches at Camping World.Moose

[TXpopper]

I've used this stuff to fix a 550 gallon plastic water tank.
Marine-Tex Putty

[campdaddy]

Well, just crawled out from under the camper. It seems that the crack is a stress crack located at a junction of  90deg angles of three planes ( See Pictures ). So, I

[tknick]

main reason not to tow with tank full is the weight.  8lbs/gal x 40gal = extra 320lbs of weight behind the axle.  that's also a recipe for a sway disaster.  Unless your systems is supersensitive, all CG water is potable and safe to drink.  you can also add a filter between the CG water supply and your PUP to further purify the water.

travis

[tlhdoc]

It the tank is full of water it will not increase sway.  A tank that is partially full will increase the chance of sway.  The water in a partially full tank will get sloshing around.  A full tank there isn't room for the sloshing back and forth.

[campdaddy]

I understand and agree that for some, perhaps most, weight would be an issue but in our case it wasn't. It's only a 15 gal tank (15 X 8 =120lbs) and it was just in front of the axle so it added very little to the tongue weight and honestly, I never noticed a bit of difference in handling. I can see though that if you had a larger tank located behind the axle it could be an issue. The biggest reason for me now, not to tow with water in the tank is the PIA it is to fix whatever cracks develop. DD

[ScoobyDoo]

A tank that is partially full will increase the chance of sway. The water in a partially full tank will get sloshing around. A full tank there isn't room

  Where the truck is your tank? Mine is 20 gal below the floor, right at the axle. If it was 10 ft in the air I might worry about 80lbs (1/2tank) moving side to side, but low and centered....

[wavery]

It the tank is full of water it will not increase sway.  A tank that is partially full will increase the chance of sway.  The water in a partially full tank will get sloshing around.  A full tank there isn't room for the sloshing back and forth.

That's right and also a half full tank of water makes one heck of a battering ram and may well damage the tank.

Think about it........10G of water weighs about 80 lbs (=8 - 10# bowling balls). You're sitting in stop and go traffic on the freeway. You start from a stop and that 80# of water is thrown to the back, the guy in front of you suddenly stops.....you hit the brakes quickly and that 80# comes flying to the forward part of the tank only to slam into a solid wall. I'd say that's a lot of stress.

[campdaddy]

This is just an info you follow up. I fixed my tank and put it back in this week-end. It leak checked good.I believe the original carck was the result of a desisn flaw coupled with the fact I was towing with it full of water. The stresses that were put on that part of the tank by the bouncing and weight were just too much and it cracked. I repaired the tank by both "welding" it and I put a roofing patch over the area for added strength. I also  put an extra brace in that area under the tank so that, even though I will not be towing with water in it in the future, it will help to control the flex involve with just putting water in it. Yes, there was aprox a 1/2in of flex in the tank at this corner just between empty and full. I can only imagine how much flex there was in this area as it's being bounced up and down from towing. If you ever have need to "weld" a tank, the polyethylene from a beer or pop 6 pack holder works well. Looking forward -still- to getting it out. The brakes have been checked and the bearings have been greased. All I need now is free week-end. :-()

[wavery]

This is just an info you follow up. I fixed my tank and put it back in this week-end. It leak checked good.I believe the original carck was the result of a desisn flaw coupled with the fact I was towing with it full of water. The stresses that were put on that part of the tank by the bouncing and weight were just too much and it cracked. I repaired the tank by both "welding" it and I put a roofing patch over the area for added strength. I also  put an extra brace in that area under the tank so that, even though I will not be towing with water in it in the future, it will help to control the flex involve with just putting water in it. Yes, there was aprox a 1/2in of flex in the tank at this corner just between empty and full. I can only imagine how much flex there was in this area as it's being bounced up and down from towing. If you ever have need to "weld" a tank, the polyethylene from a beer or pop 6 pack holder works well. Looking forward -still- to getting it out. The brakes have been checked and the bearings have been greased. All I need now is free week-end. :-()

Did you get the plastic welder or did you have it done?