Another Failed Tank Lining/Brazing question.

[Guest]

Hello Everyone, KBS Tank Coating has failed now, lasted about a week in both the tin and my tank, I am too skint to shell out for Caswells or POR 15, plus whatever you need to strip the old stuff out, although petrol does seem to do a good job, it is very expensive.
I now plan to cut out the bottom side 'fillets'? of the tank, pick out all remnants of the old coatings, braze the pinholes behind the tank badges and then braze on new metal where I cut the holes out. As far as I know it's only the holes behind the badges that are the problem, it sat with fuel in it for 12 years, though it had evaporated down to a thick coating!
Does anyone have any tips on brazing? I've done quite a few bits of ugly welding on thick metal chassis etc. and figured I might be a bit more capable with the slower process and lower heat of brazing rather than welding, plus I've only got thick wire for my mig and loads of brass brazing rods and a torch.
Thanks in advance.

[spyug]

Well the obvious , of course, is safety. You have to make sure there is absolutely no residue of gas or fumes or as soon as the torch hits it.....kaboom! You can air the tank out for weeks and there still might be enough to cause a problem so the best approach is to displace the air in the tank. You can do this by filling the tank with water but then you will require more heat to get the job done. an easier method is to use CO2. If you can run a hose from the exhaust of your car into the tank. That will do the job. You don't want to be sucking in gas fumes,however, so you need to do it in a well ventilated area and it would be prudent to wear a good gas rated filter mask.

In lieu of brazing ( which is really the best method) you can use plumber's epoxy putty to fill the pin holes. It is impervious to gas and is easy to work/shape with files and sand paper. I've sorted two tanks with this method and 5 years on they are both fine.

Good luck with the project.
Spyug

[gs850cafe]

i filled my tank with water twice...took a torch to it..in the middle of brazing..that tank shot of the bench..lost some facial hair...

just a warning

next time ill set a hose in it an let it run over for a while...then put my vaccum(which blows an much as it sucks) an sit that for a while

[razor02097]

Water alone won't get rid of the fuel. You need an emulsifier like dish soap to be able to wash gasoline out.

[rustybronco]

If it were me and it's available to you, strip the liner using M.E.K. and use phosphoric acid to remove the rust.

There's no need to cut the tank apart. Braze up the pinholes from the outside of the tank.

[Larry D]

To me, it seems easier, if not cheaper, to find another tank.

[razor02097]

Maybe in the states it would be cheaper

[EvilEnfield]

To me, it seems easier, if not cheaper, to find another tank.

Easier maybe, but I already have what I need to braze it, I would love another tank, but I'm moving house at the end of the month so I am really low on cash, and I really want to get the bike roadworthy before I go as I've got no shed at the new place until I build one.

[MisterCinders]

Well the obvious , of course, is safety. You have to make sure there is absolutely no residue of gas or fumes or as soon as the torch hits it.....kaboom! You can air the tank out for weeks and there still might be enough to cause a problem so the best approach is to displace the air in the tank. You can do this by filling the tank with water but then you will require more heat to get the job done. an easier method is to use CO2. If you can run a hose from the exhaust of your car into the tank. That will do the job. You don't want to be sucking in gas fumes,however, so you need to do it in a well ventilated area and it would be prudent to wear a good gas rated filter mask.

In lieu of brazing ( which is really the best method) you can use plumber's epoxy putty to fill the pin holes. It is impervious to gas and is easy to work/shape with files and sand paper. I've sorted two tanks with this method and 5 years on they are both fine.

Good luck with the project.
Spyug

What kind of Canadian engine puts out CO2 for exhaust? Fuel cell?

[Nessism]

My suggestion is to first strip out the failed liner. Some plumbers putty as suggested will make the tank liquid tight. Removing the old liner can be ticklish business. You might want to talk to this KBS company and ask them what they recommend for that process. MEK or paint stripper seems to work well to remove the old tank liner material, but again, KBS should be able to direct you as appropriate.

With the old liner removed, you can then focus on derusting. It's best to fully derust the tank to the best of your ability before sealing. The sealer companies suggest that you don't need to fully derust the tank before hand but don't believe them. Rust is like cancer and best results will occur if you fully derust before sealing.

By the time the tank is derusted you won't have any gas residue left so braze away. I brazed my tank using 45% silver brazing alloy, which flows at lower temp than brass, so there is less metal distortion. As always, use lots of flux and soak the tank again after brazing to remove any residue flux (which is corrosive).

Good luck.

[EvilEnfield]

My suggestion is to first strip out the failed liner. Some plumbers putty as suggested will make the tank liquid tight. Removing the old liner can be ticklish business. You might want to talk to this KBS company and ask them what they recommend for that process. MEK or paint stripper seems to work well to remove the old tank liner material, but again, KBS should be able to direct you as appropriate.

With the old liner removed, you can then focus on derusting. It's best to fully derust the tank to the best of your ability before sealing. The sealer companies suggest that you don't need to fully derust the tank before hand but don't believe them. Rust is like cancer and best results will occur if you fully derust before sealing.

By the time the tank is derusted you won't have any gas residue left so braze away. I brazed my tank using 45% silver brazing alloy, which flows at lower temp than brass, so there is less metal distortion. As always, use lots of flux and soak the tank again after brazing to remove any residue flux (which is corrosive).

Good luck.

Cheers Nessism, I wont be asking KBS to advise me on anything as they obviously know nothing!

My thinking is that I already filled the pinholes with chemical metal, I only sealed the tank as a back up, but now I've blown so much cash on it, including my lovely new paint job, I want to try and peel off the lining as I can't afford any more chemicals. I'm pretty sure that the tank is in good condition inside, aside from where it's eaten outside in behind the badges, but there is only one way to find out, and if it is in good condition then I might apply some chemical metal to the inside behind the pinholes to make double sure, that way I can at least save my paint job.

How much distortion am I likely to get on the bottom of the tank with bronze brazing (silver is too expensive) and will the filler piece distort in the same way as the rest? Should I maybe tack it in first with the MIG?

Thanks for all the replies.

[hampshirehog]

Cellulose thinners is pretty good at stripping out failed tank treatments and all sorts of other crap. Don't get ripped off - you can get a gallon of cheap stuff (gun cleaner) for about a fiver.

Plus solder the tank with plumber's solder. Get the metal ultra clean and use plenty of flux. If you can do it with an old fashioned iron (the big things you heat with a gas torch) it's easier and safer.

[EvilEnfield]

Cellulose thinners is pretty good at stripping out failed tank treatments and all sorts of other crap. Don't get ripped off - you can get a gallon of cheap stuff (gun cleaner) for about a fiver.

Plus solder the tank with plumber's solder. Get the metal ultra clean and use plenty of flux. If you can do it with an old fashioned iron (the big things you heat with a gas torch) it's easier and safer.

That's alright then, I've got loads of celly thinners, isn't plumbers solder too soft? If not then this will be a real easy job! Lead or no Lead?

[hampshirehog]

That's alright then, I've got loads of celly thinners, isn't plumbers solder too soft? If not then this will be a real easy job! Lead or no Lead?

Plumber's solder will be fine. I've done quite a few tanks with it and as long as you can get the tank clean and well fluxed it's straightforward.

[EvilEnfield]

Cellulose thinners is pretty good at stripping out failed tank treatments and all sorts of other crap. Don't get ripped off - you can get a gallon of cheap stuff (gun cleaner) for about a fiver.

Plus solder the tank with plumber's solder. Get the metal ultra clean and use plenty of flux. If you can do it with an old fashioned iron (the big things you heat with a gas torch) it's easier and safer.

Cellulose Thinners isn't touching it. From what I read, ethanol is the cheapest thing for it, (why didn't I think of that before) Do you know where I can get pure ethanol from?