repairing tank

[bryan88]

My GS500 tank has a pinhole leak and is leaking at the bottom seam. I have welding facilities and skills but have heard too many horror stories so that will be my last resort. Does anybody have any other ideas or methods? Thanks.

[Big T]

Rust removal and POR 15 liner

[bryan88]

I assume that is the commercial epoxy lining? Thanks

[pete]

http://www.por15.com/CYCLE-TANK-REPAIR-KIT/productinfo/CTRK/

That's what you want.

I didn't have any holes in mine but I had some rust issues and it seems to have worked well, although I haven't had fuel back in there yet.

There are instructions on what to do about pin holes also.

[haztoys]

Never weld on formed metal ...At some point it will crack do to the welding ... The way to fix a gas tank right is to solder up the holes ...

[Nessism]

The Caswell's Epoxy tank liner material is much thicker than Por-15, and therefore is more appropriate for sealing leaks in my view.

Fixing the leak though brazing or welding sounds like the proper process first though, although I'm not sure about the exact technical details.

[Hammered]

Use a silicon bronze filler rod with a tig. Its requires lower heat so you get less warpage and you dont have to worry about weakening the formed metal.

[hampshirehog]

Brazing or soldering is the way to go. You need to wash the tank to get rid of the traces of petrol - DON'T use washing up liquid - it foams and fuel vapour will get trapped in the bubbles (I know of several tales of woe as a result of this but never been tempted to test it myself). Washing powder -the stuff your wife puts in the clothes washing machine - is the stuff to use. It doesn't foam and cause bubbles. Melt some flux into the inside of the tank in the area that needs sealing and it will help prevent flash rusting.

[tatu]

Brazing or soldering is the way to go. You need to wash the tank to get rid of the traces of petrol - DON'T use washing up liquid - it foams and fuel vapour will get trapped in the bubbles (I know of several tales of woe as a result of this but never been tempted to test it myself). Washing powder -the stuff your wife puts in the clothes washing machine - is the stuff to use. It doesn't foam and cause bubbles. Melt some flux into the inside of the tank in the area that needs sealing and it will help prevent flash rusting.

That is the way I've done it and then just to make sure I run a pipe from the exhaust of the car into the filler of the tank for fifteen miniuts to purge the tank of any flamable gas.
I have only ever brazed up tanks it is a permenant repair and often doesn't damage the paint beyond local point.
The tank on my special developed a leak a few months back on the spot weld that holds the rubbers at the front, that was drained and left open for a week and purged with exhaust fumes then the leak was silver soldered up with an airline through the filler to cool the metal so's not to spoil a bigger area of paint, then a small area needed to be repaired at the paint shop a week later it was back on the bike. perfect.

[bryan88]

Thanks for the advice guys. Going to go the solder route (call me a wimp but still not convinced about putting sparks or a naked flame to that thing) And then probably have it de-rusted and lined commercially. Hopefully that will sort it.

[mike_of_bbg]

Pinhole leak?

Tape over and use Caswell Epoxy. Done. More than a liner it really makes a plastic shell on the inside of the tank.

[bryan88]

Thanks. Don't know about the availability of the Caswell epoxy in SA, will hunt around though.

[spyug]

Another easy fix is plumber's epoxy putty, available from your hardware store or plumbers supply store. Its a two part putty that has to be kneeded together. Once mixed you have about 10 minutes to use it before it starts to harden.

It is impervious to gas but I would also use the liner as suggested. I too favour the Caswell product over anything else. Just a word of caution with that. There is enough product to line two tanks so don't be tempted to use the whole thing. Too much and you can inadvertantly fill up parts of the tank ( like I did around the area of the sender unit...now sender won't fit in).

I did my 750 tank this way 4 years ago and its fine.

Good luck with it.
Spyug

[Normk]

A close friend repairs classic motorcycle tanks as part of his business. Doing a proper repair so that the tank looks original is not for the beginner.

I have repaired litterally dozens of fuel tanks over the decades as this was a very common shop practice in past times. I agree with the preference to solder rather than to weld because have also seem many problems following a weld in tanks. The material is often hardened/embrittled by the welding and it can be more than challenging to weld thin, corroded material. My friend TIG's his tank repairs, also for better control and weld quality.

My personal observation is that the advantage to having TIG welding done on a critical area is that, usually, the guy who owns a TIG also has the knowledge, experience and judgment. Those units are pricey so the pretenders who own them are fewer.

As for Kreem, Caswell and such, I've used both but hear from associates that they prefer Caswell these days. Professionals scoff at the use of coatings and I can see why. Stop by my friend Iron John's and look at the tanks he gets in which have these pour-in liner materials coming loose!

A big problem with them, in addition to getting the material to adhere properly over time (big problem!), is that it is very difficult to coat into the openings so that the liner is completely sealed. Often what happens is that the fuel channels back under the liner where it has not stuck to the tank in the outlet or filler area. Now you have the problem of getting that plastic out to do it again.

Soldering, another lost art, makes a very robust and tenatious coating which can be flowed over small problem areas.

Having said that, I fixed many tanks in past times using one of the coatings so you may be lucky. Cleaning the inside of the tank with a tumbler and roofing nails combined with a mix of acid is the trick whether you intend to coat or weld. Soldering allows the luxury of doing spot areas. Now, I run them up to John although you may blanch at the pricing.....

Don't worry too much about the tank blowing up. It's likely to happen only one or two times out of ten...or is that out of five... can't recall but why are my ears still ringing decades later.

[bryan88]

Thanks for the tips.