Mysterious leak from plastic fuel tank.

[Burnerman]

What would the MOT testers say about a fuel tank with patches?
I've used many sealants / repair kits on motocross bikes with plastic tanks - none lasted very long.
John

 

[Mottie]

What would the MOT testers say about a fuel tank with patches?

I wouldn’t think they could say anything if it wasn’t leaking.

 

[Old Salt]

I would try some fibre glass to make an overlapping patch. Really clean and score the area then whack some resin and fibre glass on it in several layers (at least 3) then leave it to cure. Fixed my merc undertray.

 

[Avocet]

What would the MOT testers say about a fuel tank with patches?
I've used many sealants / repair kits on motocross bikes with plastic tanks - none lasted very long.
John

I'm not going to try any sort of patch. If it was a repair, it would be a weld. However, I've only had one quote back for welding and it was £200 + VAT with no warranty. I know I can get a second hand tank for £280 all-in, so I'll just go with that, I think.

 

[Avocet]

I would try some fibre glass to make an overlapping patch. Really clean and score the area then whack some resin and fibre glass on it in several layers (at least 3) then leave it to cure. Fixed my merc undertray.

Sadly, it won't work. It's a high density polyethylene tank and I know polyester resin won't bond to it. You can (sort-of) get it to "stick" by mechanically roughening the surface, it's at the bottom of the tank, so long term, I don't think it would ever seal.