What glue should I use to fix a small crack in my freshwater tank?

[JimGolden]

Hi everyone,

I have discovered the source of the small leak in my fresh water tank. My tank is L-shaped and at the top of the tank in the inside of the L-angle, I found a very fine crack in the tank.

I discovered this very scientifically; I took my shop vac, hooked the hose to the blower side, made a funnel out of a 2L pop bottle, then lightly pressurized the tank. Had my wife hold the funnel and hose assembly to the fresh water inlet door and I went inside and reached through an access door to find where the air was coming from. The low pressure air worked like a charm

So my tank is the standard white plastic material. I would guess it is polyethylene or polypropylene. What glue should I use to fix this hairline crack? 2-part epoxy? PVC cement? Model airplane glue? I don't have easy access to a plastic welder either. Would prefer to just glue it shut if possible.

There's really not much room to glue another piece of patch over it. I don't think that I really need a patch; the crack isn't even visible to the eye. But you can feel air coming through it. The leak was about a drop every 15 seconds, but I lost probably 10 gallons over a weekend and it's not good for the floor/belly pan. I want to fuse the plastic shut.

I am fortunate in where the leak is located. It is relatively easy to get at. I just need to find out what the right glue is for this. Any help would be appreciated.

thanks!

[Inland RV Center, In]

Originally Posted by JimGolden

Hi everyone,

I have discovered the source of the small leak in my fresh water tank. My tank is L-shaped and at the top of the tank in the inside of the L-angle, I found a very fine crack in the tank.

I discovered this very scientifically; I took my shop vac, hooked the hose to the blower side, made a funnel out of a 2L pop bottle, then lightly pressurized the tank. Had my wife hold the funnel and hose assembly to the fresh water inlet door and I went inside and reached through an access door to find where the air was coming from. The low pressure air worked like a charm

So my tank is the standard white plastic material. I would guess it is polyethylene or polypropylene. What glue should I use to fix this hairline crack? 2-part epoxy? PVC cement? Model airplane glue? I don't have easy access to a plastic welder either. Would prefer to just glue it shut if possible.

There's really not much room to glue another piece of patch over it. I don't think that I really need a patch; the crack isn't even visible to the eye. But you can feel air coming through it. The leak was about a drop every 15 seconds, but I lost probably 10 gallons over a weekend and it's not good for the floor/belly pan. I want to fuse the plastic shut.

I am fortunate in where the leak is located. It is relatively easy to get at. I just need to find out what the right glue is for this. Any help would be appreciated.

thanks!

Glue is a no-no.

For a quick repair, for a "small" crack, fuse it back together with a small "soldering iron." Or, melt some of the same material, scuff the surface, and pour it on.

That tank is a crazy design and it's been obsolete for 30 plus years, so be careful.

I have the drawing for it and no one wants to get involved making it again, unless you order 25 or more.

Andy

[somefun]

I'm getting ready to repair some cracks in my black water tank (low density polyethylene), and I'll be using Scotchweld 8005. I should know how it worked by this time next week. Copy and paste the following into the search box on Google for some good info on this product:
site:www.airforums.com scotchweld

[SteveH]

I've had good luck with Household Goop for such uses. It's a very thick silicone that hardens well, and is waterproof.

[JimGolden]

Hey Gang,

Just a final report on my tank repair. I looked into that 3M Scotch Weld DP-8005 and it looks to be the only glue in the world made for polyethylene. I couldn't even find it locally. So....I looked online and saw that it was $30 for a tube of it and about another $40 for the applicator tube. So.....I called up a guy I know who is a 3M rep and said "How 'bout a sample?" Dude hooked me up

I cut a thin piece of polyethylene about 1" by 2" by 1/4". Cleaned both the tank and the new piece with alcohol, let it dry, then glued her up. 24 hours later I did my air pressure test and it held just fine. Filled her up and no leaks. It's been holding for days now.

So anyway, if you don't have a hot air plastic welder or other similar tools or access to the place is tight, I think this product from 3M will work just fine. It seems to be a great product. Even if you had to pay the full fare, I think it'd be worth it.

See ya on the road,