Lil4X

If you have a cracked coolant recovery tank, windshield washer reservoir, or even a brake or power steering fluid tank, there may be a cheap solution rather than paying big bucks for a replacement online or at the auto parts store. You can try "welding up" the crack using polyethylene scraps as "solder".

About six months ago our old beatervan started leaking coolant, slowly at first, but this spring, more rapidly. I finally found the leak was coming from a crack out of sight in the bottom of the coolant recovery tank. Looking for replacements online, I discovered a new tank was worth about 20% of the value of the entire vehicle, and a used one would be only about $30 cheaper. Nuh-uh.

Probably 30 years ago the filler neck on the polypropylene water tank in our motorhome cracked as the result of a poorly-engineered installation that left 40 gallons of water (~ 280#) of sloshing content suspended on one end by the filler neck. Insert shim on after end of the tank, problem solved . . . not so the fix. The weight of all that moving water finally cracked the filler neck and the carpet was getting wet if we had more than 20 gallons of water in the 40 gallon tank.

First we had to drain and pull the tank, which was a relatively simple task, but the repair of the heavy gauge polypropylene tank was a question. OK, today a quick look at the internet would have yielded an answer, but in the mid '70's such help was not available.

Epoxy or almost any glue won't stick to poly, nor will any ordinary adhesive . . . as we found through experimentation, and we were searching for an alternative to a $400 tank to fix a botched factory installation. There had to be a way of joining polyethylene without the big induction heaters used at the factory to modify blank tanks into a custom installation.

Browsing an issue of "Trailer Life" magazine (for RV'ers), I found an ad for a tank "repair kit" for $20. Sounded like a bargain until it arrived in the mail. Two 2½" discs of polypropylene were in the package, obviously cut out by a hole saw during installation of a a filler neck in a new tank . . . that were otherwise scrap. I thought I'd been had. Fortunately a Xerox of instructions came in the package: cut the disc into ¼" strips and heat with a soldering iron (one of the big ones that plumbers use), heat the area carefully and flow he stick of poly into the crack using melted poly as "solder". Allow to cool to the touch and voilį, a strong repair! It isn't pretty, but it works great - as strong as the original material itself. If you're in a jam, you can cut up a milk jug into strips it's the same stuff, but that poly is so thin that it will want to burn and turn a dark brown as it is heated to its melting point. Still, it makes a strong joint however the repair leaves a gnarly brown scar.

We used the same technique to divide the water tank in the boat's galley into separate water and holding tanks when the EPA made overboard drains illegal. Complete success! Again, not exactly pretty, but completely functional - and complied with new EPA regs to boot. Appearance didn't really matter in either application, because they were hidden in cabinets where they survived years of service without leaking a drop before the boat and motorhome were sold on to new owners.

I'll report back on the success or failure of this project later in the week, but I have my marching orders now - and as soon as the weather warms a bit, I'll try it out. Molded poly tanks for coolant recovery, windshield washer reservoirs, even brake fluid reservoirs are not cheap, but a few strips of polyethylene and a big soldering iron are. Don't pay the big bucks for a 50¢ repair.

BDSL

Duct tape?

tghw

Can it be done? I'm sure that it can, but I wouldn't waste my time trying to repair one when you can pick up cheap used ones on EBay. There are salvagers parting out wrecked Lexus all the time.

Lil4X

Current price new: $90 - $160 plus shipping to fit a 99 Dodge Caravan. That's full retail at any auto parts store - No way! Van's only worth maybe $500. Cheap solution first.

Maybe Flex Tape?

fastnoypi

TAP Poly-Weld Adhesive