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I bought my 1980 FLH 80 in a non-running state this September. Spent quite a bit of time and a little bit of money getting it work like it ought but I'm in North Dakota where the riding season isn't too long. Frustratingly, we had a nice day a couple weeks ago and I decided to go for a ride. For the first time, then, I filled the tank to the top. And it leaked. These tanks looked spotless on the inside, but when I took the leaky one off, I saw that it looked like it must have been dropped or something because in an odd spot, it was obviously fixed at some point and that fix leaked. So, I took it to a local body shop and he didn't want to weld it and used an epoxy or something to fix it. It was more money than I wanted to spend, but when I put the tank back on the bike, it still leaked. This time by the rear mount hole. I don't intend to go back there.
It's a bit frustrating because the tanks look nice. But, now I'm contemplating taking it to a different body shop or just buying a new tank. The problem with buying a new tank, of course, is that it's not going to look like it ought and the original tanks look nice. If I were to go this route, are there any suggestions in terms of where I would get a new tank? I do see Dennis Kirk has a few options but terms they use are unclear to me... should this be the 3.5 gallon bobbed tank like this: V-Twin Manufacturing 3.5 Gallon Bobbed Gas Tank - 38-0112 Harley-Davidson Motorcycle - Dennis Kirk ... or?
If the cracks aren't too visible, you can try soldering them. I did my 79 FXE and it worked great. I had to remove some paint naturally, but you don't need as much heat as welding so the area was smaller.
I use Seal All... lasts couple 3 years...sometimes more...depending on vibration...
Edit; I like...and will try, the solder idea!!! But...being lazy, I smear seal all right over paint and all...don't even empty gas tank...Magic ****!!!
Last edited by Racepres; Dec 26, 2023 at 06:48 PM.
DONT BUY V-TWIN TANKS !!!.... they are NOT the same shape or fitting as factory tanks at all, just cheap Chiwanese copys not worth trying, if anything your better off buying used genuine on ebay and get them painted to match the bike after pressure testing to make sure they are good to run, also NEVER use a tank sealent, they are a cheap (but expensive fix) that always goes wrong eventually with modern fuels eating them, they also prevent you properly fixing them at a later date by welding if another crack or leak happens somewhere down the line.
personally, I would find a GOOD TIG welder, strip the area around the leak and get it welded properly, that way its done and never need to worry, but depending where the leak is it may need repainting after,....
where is the leak exactly ?... post a picture please...
DONT BUY V-TWIN TANKS !!!.... they are NOT the same shape or fitting as factory tanks at all, just cheap Chiwanese copys not worth trying, if anything your better off buying used genuine on ebay and get them painted to match the bike after pressure testing to make sure they are good to run, also NEVER use a tank sealent, they are a cheap (but expensive fix) that always goes wrong eventually with modern fuels eating them, they also prevent you properly fixing them at a later date by welding if another crack or leak happens somewhere down the line.
personally, I would find a GOOD TIG welder, strip the area around the leak and get it welded properly, that way its done and never need to worry, but depending where the leak is it may need repainting after,....
where is the leak exactly ?... post a picture please...
I tried one of those bargain tanks once ... That was enough :<(
My paint really isn't a concern as this is on the frame side and it's already fairly unpretty. I'm just not sure I would be able to use seal-all or solder because it's hard for me to see even where the issue might be. It is, most certainly, leaking around this rear mounting hole. You can see that it was fixed once upon a time -- and -- of course -- it gets wet when you put gas int the tank. I also have a fear that the location of this might be very difficult to ever rectify with a 'quick-fix' as obviously vibrations will have an impact here.
Looks like it's had a previous weld (solder) repair attempt, but the rust has left the metal too thin to have any strength or metal to weld to. Or the rust wasn't removed and sealed so it just rusted out again.
Not sure a selant is going to help considering the gap size. And to properly seal a tank you must remove all rust and any previous sealant. And the last thing you want to happen is the tank start leaking on a hot engine while riding down the road. So if it were mine, I'd be looking for a good used replacement tank. There are usually several swap meets this time of year and in the spring that may have what you want.
Even with a used replacement tank, it would be advised to clean it properly and seal it. I've had the best results from Caswell tank sealant kit. It's not cheap, but I've never seen one fail if the tank was prepped correctly.
Seal all the openings, fill her with compressed air and soap her down looking for bubbles. Will not take much air to find the leak, then you know for sure what you are dealing with, good luck.
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Tank Woes
