OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines FUEL TANKS: Best Method to Repair Plastic Tanks

I have had a number of Briggs and Stratton quantum mowers that have had split seams in their plastic fuel tanks. It is always around the seam on the engine side. I have tried "plastic welding" with a soldering iron and some scrap plastic. This was unsuccessful or just temporarily successful and may have failed because the two plastics have to be exactly the same. However, I had a friend who said he had his son try and do this and it also failed and he was a professional plastic welder.

I have tried hot melt glue, also a temporary success, I've tried an epoxy mixture that is very strong and works under water etc-too I think it was too rigid and the seam opened up again. I have also tried one of the permatex gasket products and it was totally useless. So I was wondering if any body has had a successful repair on a plastic fuel tank seam and, if so, can they share it with me.

i have never tried really , almost always have a spare laying around somewhere here as they get beat to death in my neck of the woods , sorry i did try once but same thing lasted maybe a couple of months in season and cracked again but different place .
when i fit them just make it as easy and loose as possible so nothing is stressed then tighten bolts seem to last the life then , often its because the spacer under the 10mm at the rear is dropped when removed then refitted with it missing (stressed) so sure somethings gotta give .

good luck with them though , if you work out a way let us know as it never really works for long

, Dave

Yep, the filler rod used has to be the same type of plastic, for welding to work.

So it's necessary to look for a type marking, or recycling symbol, on the tank.
The most likely culprits would be PP [polypropylene], HDPE [high density polyethylene], or ABS [acrylonitrile/butadiene/styrene copolymer]. HDPE can't be glued, but the others can, with the right glue and techniques.

That said, the seam design on these doesn't lend itself to being patched up. I'd say they are ultrasonic welded at the factory, but that isn't really available as a repair technique. Any welding/glue just on the outer edge of the seam isn't going to have the strength to last.

It would be necessary to either split the entire seam to get a good glued joint, or cut a vee on the outside with a burr cutter, to get a decent weld, I'd say. Even then, you'd really need a pro-style hot air welding setup to get a good joint - soldering irons just ain't going to work.

For the most common Quantum tank, the #699374, the ODK Shop has them for $46.50, or they are usually on FleaBay Oz for about $57 posted

Good stuff. Neither of the purchase options are viable unless you were working on a keeper. I sell most of my mowers for $65 but as you know you can pick up a junk mower for $20 and that's how most of us get our spares of course. You'd think fixing a leaky plastic seam on a tank would be simple. I never considered splitting the whole seam for a better join and I might give it a go next time. I've also got a heat station and also a heat gun. I'll see how much damage I can do with those as well.

There is an industrial glue for HDPE plastics available though it is very expensive in small quantities plus you must have the application gun and tips.

Here is a link the product's literature.
ClicK Here

As welding you must keep the temperature within very close tolerances, too little result in poor bonding and too much result the plastic structure being burnt. Also as said before it needs to be a full penetration weld on clean materials. I have weld these tanks for my own use but I prefer to just replace the whenever possible on customers equipment; just not worth the liability.

I think the message here is to NOT try and repair them. Sad thing is I bought one last week from the recycle centre for a mower I that did not have a tank (also from the same place. That's the one with the leak and I bet it came off the same damn mower too. Sometimes you can't win.

That also makes the case for them pressure test tank before you buy and leave with it. Here before let the customer have an used I pressure test it so I know it leaves in good condition.

Absolutely!