Fuel Tank Leak Repair!

[AresROC]

The night before Sunday ride, noticed gas smell and green fluid under the bike. It came from the fuel tank... Apparently this is another common issue.

I was partial to blame, since the rear bolt was loose I put a lock washer on it and tightened it. That was the mistake I should have left it loose to absorb the shock better. The seat would have kept it in place.

Current plan is to get fuel tank epoxy from AutoZone to fill the internal seams if I can reach inside the tank, and sweat solder fill the external rear seams.

[Megadan]

Two hawks and almost 6000 miles between them and I have never had this issue. Hopefully you can get it sealed back up.

Tip for tightening that bolt - This is a bolt I use loctite on, and tighten it until the rubber deforms just a little bit, a lot like a sway bar link bushing (if you have experience with that). It shouldn't need any more, and as you said, even if it does come loose the seat will hold it on. Plus, the resistance from the rubber actually acts a bit like a lock washer already by apply force to the threads.

[Red Hawk]

I cut a piece of 1/2” sheet rubber about business card size to spread the contact area out back under and away from the seam. If my tank ever leaks it’s getting cleaned out and brazed along that seam. Not a fan of any epoxy plug. Once and be done with it forever.

Bad timing on a fuel leak here or a fail on the patch and your birdie is cooked. Braze it.

[AresROC]

It appears the leak is coming from a weld line in the back of the tank. A friend of a friend is a good welder and applied a new weld for me. Can't wait to put it back on the bike!

[Red Hawk]

Nice repair.

I’d fill it partially and let it sit overnight. Not questioning the repairman just easier to spot a slow seeping drip unmounted.

[pete]

fill it with kerosene... it will find cracks/leaks that fuel won't..
kerosene has very small molecules and low surface tension
unlike petrol or water...

or soapy water and air...


..

[AresROC]

Seems leak free so far! Problem is water was filled and now there are some rust inside the tank. Any way to get that rust out?

[Landsvw]

I wouldn’t even worry about the tiny amount of rust a few days of water in the tank created. Empty it, maybe blow it out with an air hose, maybe fill it with gas and put a tiny bit of Heet (alcohol used to absorb water) in it, and you’re golden.

[Red Hawk]

It’s basically Vinegar at industrial strength. Strait White vinegar works but slower too. Wash it out with gas and refill immediately after and it will pull off rust you swore was permanent. You can find it at Harbor freight.

[AresROC]

Originally Posted by Red Hawk

It’s basically Vinegar at industrial strength.

I actually have a bottle of that at home and was thinking about using it. I also have the acid/bluing rust preventer Krud Kutter I have been using on the frame.
Used some gas to rinse the water out and air drying overnight with a fan. Will apply rust remover and get some heet today. Thanks for all your help!

[culcune]

I remember having a leaking tank on my TMEC and going to the local ACE hardware store and buying something that specifically was made to fix leaks and was not affected by oil and gasoline. Worked like a charm.

[alex_in_az]

I made a fuel tank for an old Lotus 7 I had and used POR-15 tank sealer to take care of a couple of leaks in the welds that I couldn't fix

[AresROC]

Evapo-Rust, this stuff works amazing. About 15min each side and work all 6 sides. Dump the whole bottle in, let it work; dump it out in a pan, filter out the rust with shop-towel and save the stuff for next time.