prepping a gas tank for welding ....

[3imo]

...is a bi*ch.

I need to get the dents outta the tank for my 01' rebuild project. LINKY

My solution is to use a slide hammer to pull the dents out and try to smooth them out.  I have experience in dent removale for cages but not MC gas tanks. I will have to weld the holes created by the slide hammer.

Anyone done this before?  any insight on how much of a pain in the ass this will be?

BIG Question -----  how do I get all the gas out? welding and gas don't mix.  KAboom, big bada BOOM.

[Chuck]

Dan's Motorcycle says to fill it with an inert gas.

http://www.dansmc.com/gastank.htm

[3imo]

Thanks.  I've read his site through and through, but theres gotta be another way.

I'm gonna try soap and water, but I know I'm treading on thin ice.

[werase643]

take it to a radiator shop
they will boil it out in whatever solution they use
and they will braze it up also for very little

[LimaXray]

Do you have a mig welder? why not fill it with argon?

[Dwn4whadever]

...is a bi*ch.

I need to get the dents outta the tank for my 01' rebuild project. LINKY

My solution is to use a slide hammer to pull the dents out and try to smooth them out.  I have experience in dent removale for cages but not MC gas tanks. I will have to weld the holes created by the slide hammer.

Anyone done this before?  any insight on how much of a pain in the ass this will be?

BIG Question -----  how do I get all the gas out? welding and gas don't mix.  KAboom, big bada BOOM.

A good idea to get the dents out the gas tank might be putting water in the tank and freezing it. Letting the water expand and knock the dents out. Might work im not sure.

[Cal Amari]

The metal around the dents will be work-hardened; freezing water in the tank will only stress any weaker spots first, and I DON'T recommend it at all. I understand the thought behind the suggestion, but it won't work as a practical solution.

I've often wondered if a different approach might work; filling a tank with clean sand (NOT sawdust, which would be flammable), or something similar (colored aquarium gravel? does that stuff melt?), might do the trick if the gas tank was clean inside. The sand should displace most of the air/oxygen in the tank, and won't support combustion. I think you could avoid making holes for the dent puller completely if you spot-welded a LOT of nails to the dented area, then rigged the slide-hammer to pull on the nail shafts; the welded-on nail heads would pull the metal out a few millimeters, bringing the metal (somewhat) back to the original shape. This would require some trial-and-error, but if you heated the damaged area with the torch, the sand behind the metal might hold enough heat to keep the area fairly hot while you work the metal. You might have to reheat the area every few minutes, but that should still give you plenty of time to pull the metal closer to where you want it, using the slide-hammer (or whatever) to pull the nail shanks. Once you're satisfied with the results, remove the nails and grind down the welds; no hole-filling required.

Don't really know if this will work for you, but if you want to try it, keep a fire-extinguisher handy, and think it through before you begin. You might be aware of a hazard I'm overlooking...

Either way, I'd appreciate some feedback on this, from one and all...

[3imo]

Thanks CAL.   I like that idea about the nails.  I'll have to rigg the dent puller but it'll work

Werase-- I am gonna check with the local radiator shops and see what they say.

LX-- I'm using a flux core welder. the gas is produced by the wire itself.


any more Ideas?

[CRXDrew]

welding nails on will work. In the body repair industry they use a "stud welder" which is essentially the same thing... its just made to tack on a lil stud that is made to be pulled by a slide hammer. Depending on dent size (for smaller dents) I would try to use a paintless dent removal tool... "Ding King" comes to mind. Otherwise... if the dents are mostly small u can hit it with a "ding King" and then just bondo over the minor imperfections.

[LimaXray]

Sorry to thread jack, but... How well does the flux core welder work?  I'm thinking about getting one cause I don't want to deal with the gas but have heard mixed reviews

[TragicImage]

I really really really liked the sand idea.  Many potential benifits... and relatively good idea for removing oxygen from the mixture.


However, depending on how course of sand you use, it might be a pain in the ass to get it out of corners when you're finished.

[CRXDrew]

Sorry to thread jack, but... How well does the flux core welder work?  I'm thinking about getting one cause I don't want to deal with the gas but have heard mixed reviews

FluxCore welding is ok... but you will not get the prettiest welds. With practice, good prep, and anti-spatter spray I can lay a very nice bead that is acceptable for any exhaust work. I have had experience making turbo manifolds for honda's using fluxcore welding and they are fine. Just not the all the bling that people see when using a several thousand dollar TIG welder. Basically... ur probably better off buying a decent welder that has gas capabilities and start out with fluxcore wire... then down the road when you are ready to step up you can go out and buy the gas/solid wire... and then kick yourself for not doing it sooner.


I personally don't like the sand idea at all. Think about going to the beach.... sand in weird places for days. I say just strip the tank down and let it air out. If you have a compressor that would help... have it blow air through the tank for a while... all the gas will evap and u'll be good to go.

[3imo]

FluxCore welding is ok... but you will not get the prettiest welds. With practice, good prep, and anti-spatter spray I can lay a very nice bead that is acceptable for any exhaust work.
Basically... ur probably better off buying a decent welder that has gas capabilities and start out with fluxcore wire... then down the road when you are ready to step up you can go out and buy the gas/solid wire... and then kick yourself for not doing it sooner.

+1  not pretty but it does the job.  Plus It make me a better grinder 

[LimaXray]

Sorry to thread jack, but... How well does the flux core welder work?  I'm thinking about getting one cause I don't want to deal with the gas but have heard mixed reviews

FluxCore welding is ok... but you will not get the prettiest welds. With practice, good prep, and anti-spatter spray I can lay a very nice bead that is acceptable for any exhaust work. I have had experience making turbo manifolds for honda's using fluxcore welding and they are fine. Just not the all the bling that people see when using a several thousand dollar TIG welder. Basically... ur probably better off buying a decent welder that has gas capabilities and start out with fluxcore wire... then down the road when you are ready to step up you can go out and buy the gas/solid wire... and then kick yourself for not doing it sooner.

Thats what I was thinking about doing: get a welder that can do either gas or gasless minus the regulator and what not, and start off gasless.  All I see myself using it for now is to fabricate my own downpipes, which is probably a lot more forgiving then welding manifolds.  Bling doesn't matter to me, the downpipe I have now was stick welded and looks like shaZam! but works great.  As long as it doesn't leak I'm happy

[Cal Amari]

"Airing out" a tank before welding DOESN'T work; just ask anyone who has tried it (which includes me, more than once). Filling it with water won't work either; again, I know this from first-hand experience. A friend bought welding equipment from a small shop which was closing (the owner was retiring), and we wanted to test it out by repairing some gas tanks (one from a Yamaha XS650, one from an old Jeep). We tried a few different methods, none of which worked well at all. The friend has long since moved, so I no longer have access to his oxy-acetylene or MIG welding equipment.

The sand SHOULDN'T present a serious problem, though after giving it a little more thought, I would recommend pouring the sand through a mesh screen first, to eliminate as much sediment and small particles as possible; pea-sized gravel (available at any store that sells landscaping products) would also be an option. Obviously, the gravel would be much larger than sand particles, and there may be other products I haven't considered yet. After heating / welding the fuel tank, just flush the tank thoroughly multiple times, and use a fuel filter in each of the gas lines (main and reserve) coming from the fuel tank; I have fuel filters installed and check them frequently for signs of rust or other crud. Since they don't fit well side-by-side, I have them staggered, with one closer to the fuel tank, and the other closer to the frame-mounted petcock. The fuel filters should prevent any serious problems; if they clog quickly, it would indicate that the tank needs to be flushed again.

I made those suggestions because it seems obvious to me that 3imo has the skills and experience to overcome any problems he encounters; the photos he's posted so far show that he is both intelligent and resourceful, and I believe he can find a suitable way to make this method work, unless he chooses to have the repairs made professionally.

CRXDrew: Thanks for the information about the "stud welder"; nice to know that such a device actually exists. Now, I'll have to stop in at a local body shop, so I can see one in action. I wonder how much they cost...

[facio57]

well as someone who had a whole in their gas tank and got it fixed, i can tell you, no one will weld it, and for good reason.  that thing is a bomb! what they will do, is solder a piece of metal over the crack or hole for example. soldering: no open flame=no explosion. i had this done and am very satisfied with the results. i wouldn't go through the trouble of putting sand or whatever in, can u imagine what a pain in the ass it will be to get it all out? call around radiator shops and ask if they will solder it.  good luck!

~facio

[3imo]

I would weld it.......

I am sure I could find a place that would too.  lots of things are dangerous..if done wrong..  even motorcycle riding.

If I go Kaboom...tell my freinds I died as I wanted to go.....with a bang   

[werase643]

welder...MILLER XP135 . . .   best most expensive cheap wire feed welder
it's about 700 for the set up
much better than the 400 ones

stud gun....Harbor Freight...bout 100 bucks and ya don't destroy the integrity of the tank....no welding up the holes

[CRXDrew]

stud gun....Harbor Freight...bout 100 bucks and ya don't destroy the integrity of the tank....no welding up the holes

Beat me to it :-p. I've heard of mixed results using these HF ones... but then again there are mixed results for everything they sell.


Solder is a good idea for a nick/crack. I would go with brazing if need be aswell. You can get brazing stuff @ Home Depot and the like. I can't see how bad a tank could possible be to repair. I was just thinking you could rinse out the gas and go to town.

<-- motorcycle noob.. for now.

[budget speed demon]

apparantly its almost imposible to weld oem gas tanks because they are made from such thin metal. I'm not sure how true this is on the GS, but I know its true on older bikes.