Fuel tank repair (1983 GS850G)

[Wombat_Scat]

Hi guys, I have recently picked up a 1983 GS850G in awesome condition apart from one thing, the fuel tank has a small leak. I think there was some significant rust and the past owner had soldered most of the hole. you could visibly see a tiny pinhole amongst the solder job so first tried using JB tank weld putty for a quick fix which didnt work, I then sanded the putty off and tried soldering the hole myself with no success. I now think the leak is coming from the seam along the bottom of the tank where the two halfs are welded together. Has anyone had an issue like this? I'm thinking of stripping all the paint and then having someone weld over the seam. Is there a better way I could fix this? Should I try soldering over the seam instead?

[Wombat_Scat]

Here's another picture.

[Nessism]

Is the exterior paint critical to save? Assuming no, then I'd get some phosphoric acid from Home Depot, aka Kleenstrip etch and prep, and soak the tank inside and out, to eat out all the rust. When done, there is going to be some holes, so patch them on the outside using duct tape, then seal the inside using Caswell's tank sealer. That stuff is killer thick, so cut it to the extent recommended in the instructions. The rest is up to you, in terms of performing a proper coating. It's a little tricky, in that you need to flow the material all over the interior of the tank, until the stuff starts to harden and stop flowing. Only then can you put the tank down, and rest.

[Wombat_Scat]

Is the exterior paint critical to save? Assuming no, then I'd get some phosphoric acid from Home Depot, aka Kleenstrip etch and prep, and soak the tank inside and out, to eat out all the rust. When done, there is going to be some holes, so patch them on the outside using duct tape, then seal the inside using Caswell's tank sealer. That stuff is killer thick, so cut it to the extent recommended in the instructions. The rest is up to you, in terms of performing a proper coating. It's a little tricky, in that you need to flow the material all over the interior of the tank, until the stuff starts to harden and stop flowing. Only then can you put the tank down, and rest.

Because I'm looking for a quick fix right now so I can ride over the summer, do you think putting putty or soldering over the seam could work until winter when ill strip the tank down and do it properly?

[Nessism]

You can try. If you solder, heat may open up more holes. If so, switch to the sealer stuff.

[Wombat_Scat]

Is the exterior paint critical to save? Assuming no, then I'd get some phosphoric acid from Home Depot, aka Kleenstrip etch and prep, and soak the tank inside and out, to eat out all the rust. When done, there is going to be some holes, so patch them on the outside using duct tape, then seal the inside using Caswell's tank sealer. That stuff is killer thick, so cut it to the extent recommended in the instructions. The rest is up to you, in terms of performing a proper coating. It's a little tricky, in that you need to flow the material all over the interior of the tank, until the stuff starts to harden and stop flowing. Only then can you put the tank down, and rest.

will the kleenstrip take the exterior paint off or should I do that beforehand?

[Nessism]

will the kleenstrip take the exterior paint off or should I do that beforehand?

I'd strip it beforehand. Often times there is a lot of spider-web corrosion under the paint, and stripping the paint is the easiest way to see it, and thus remove it.

[Wombat_Scat]

I'd strip it beforehand. Often times there is a lot of spider-web corrosion under the paint, and stripping the paint is the easiest way to see it, and thus remove it.

I guess that's my plan for the weekend if 1 last putty attempt doesn't work to give me a quick fix.

[oldGSfan]

I have a Caswell kit never opened, plus some POR-15 etching solution. If you are going that way, shoot me a PM, I will send to you for less than half price to do the tank. The little clips on the cans have never been pried off, I can open up to check the status of the liquid. I need to shift some stuff that's just on the shelf. I remember i mistakenly ordered POR-15 and Caswell kt, and ended up getting the POR-15 first and used it. Then.. surprise!

[nvr2old]

You might consider stripping off all the paint to reveal what damage needs to be repaired and then take it to a reputable radiator repair shop. They deal with leaks all the time, and, they can strip the inside by boiling it out, and then coat the inside plus pressure check it once it's done.

[Nessism]

I have a Caswell kit never opened, plus some POR-15 etching solution. If you are going that way, shoot me a PM, I will send to you for less than half price to do the tank. The little clips on the cans have never been pried off, I can open up to check the status of the liquid. I need to shift some stuff that's just on the shelf. I remember i mistakenly ordered POR-15 and Caswell kt, and ended up getting the POR-15 first and used it. Then.. surprise!

The Caswell stuff is great for tanks with holes, because it's THICK! I used it on a tank with leaks, after taping over the holes on the outside, and that tank was solid when finished.

[alke46]

You might consider stripping off all the paint to reveal what damage needs to be repaired and then take it to a reputable radiator repair shop. They deal with leaks all the time, and, they can strip the inside by boiling it out, and then coat the inside plus pressure check it once it's done.

+1 on what ^^^ said. I did that a few years back and while it may not be the cheapest way to go, IMO, it's the best way to go.

The reason I say it's not the cheapest way is because you will have to paint it afterwards.