Sealing Wombat tank with minor leak

[Brian4236]

Howdy, everyone. The tank on my '72 wombat has a very minor leak in the seam. This is a tank that has been chromed and is in otherwise good condition. For those of you who have sealed a Hodaka fuel tank, what product do you recommend and what helpful hints do you have for doing this work? Thanks. --Brian

[viclioce]

If it's a seam you may be able to fill it with solder. But you need to make sure you wash the tank out with soap & water and then fill the tank with water, put the cap on and flip it over. Use a small butane pencil torch. Heat the area, clean it with a small wire brush and then heat it again and solder in the seam. You should be able to do it without seeing any heat damage! ; D Victor

[Zyx]

I agree with Victor except for the "filling" part. If the part to be soldered is in close contact with water you will never get it hot enough to melt solder. Wash with soap, yes. Even leave a bit of dish soap in the water in the tank when you go to solder it because the surfactant keeps gas from being an issue. But water should be a ways away from the work area or it won't get hot any time today. Actually, if you thoroughly wash with dish soap, it won't go boom anyway, and you can just solder with the cap off the tank. Spooky the first time, but wash until you can't smell gas or see oiliness in the rinse water, and there is not enough fuel left to be an issue.

[Brian4236]

So, neither of you is a fan of a sealant? I guess I'm a bit nervous about things going "boom."

[Zyx]

Gas tanks can be safely welded. They just have to be clean. If you cant smell gas, and if rinse water shows no oil slick, there is no fuel, just don't put on the cap, more due to warpage than danger. Here, we have a nicely chromed tank, and welding would certainly damage the look. Internal sealants can also work, but most are tedious.

My only concern is that the leak is at a seam. It is likely to keep leaking if the seam is opening up, as opposed to rusted through. Solder will hold up to a point. Brazing is better but needs far more heat and could also damage the chrome. I guess it would be a judgement call how to fix it. If you use a sealant product and it doesn't work, how do you get it out of the tank? I have never tried sealants so can't attest to or warn against. Just don't know. At least with solder, if it doesn't work, nothing is lost and you can still try something else. Haven't tried soldering chrome, but the steel underneath should hold a solder joint.

If it were mine, I would use braze because it makes a more certain repair especially if you can get it to chase flux into the seam crack.

[Brian4236]

OK, will give it a go. Thanks to each of you for responding.

[bobwhitman]

Few here are fans of sealant, especially "Kreem." Other sealants draw some supporters, but Kreem is not much loved by folks here. I've actually used JB Weld on certain tank holes (not especially seams) and Darrell Ohs wrote in the Resonator Revisited (R2) about using fiberglass and "Downey" fabric softener sheets to seal a tank.

See what you're missing if you aren't a Hodaka Club member and reading the R2?

Bob