Topic: So...how do you braze or solder a tank?

[VTCBike750]

So after searching around the forum I was only able to find threads that suggested brazing a solution, but nothing on how to braze.

I know its a subject that's been beated to death, but I recently got a 73 750 tank with a pin hole leak. When purchased, it had minimal rust. It was run on a 12 hour 1 amp electrolysis cycle, cleaned with the works toilet bowl cleaner, and then ATF used to prevent flash rust. Everything was going great until I put gas in it.

I was hoping a few of you could push me in the right direction and help me braze this tank. I've never done it before. Ive been reading up on it, and need some suggestions on what to buy (what kind of torch and filler works best with our tanks) and some basic techniques.

Here's what I'm working with:







So, where do I go from here?

[vaughnsmith]

Are you good at soldering?  If you are good at soldering, you can braze.  Works the same way- heat the metal not the rod, let it flow to the heat.  But if you don't have the torches already, me not be a good investment.

I have all the stuff, and almost never use it.  Instead I got a cheap mig welder and use that for about everything.

On my dirt bikes I used the caswell sealer kit a number of times.  Had an old BSA (500 single) and I just put tape on the outside and pored in the sealer.  Never had a leak or rust after that.  Also used it on glass and plastic tanks that were damaged. 

[VTCBike750]

I might need to buy a torch to heat the cases if I ever get to swapping out the studs. But would a MAPP torch be too much heat on the cases?

Anyways, I think its something I can do. Id rather learn how to do it and have the stuff around too. I guess it comes down to whether I can find someone who can do it or whether its worth it for me to invest in the equipment.

[lucky]

Do not weld on gas tanks!!!

[trueblue]

I had a few holes in my tank, up to about 1/4",  I used lead solder to fix mine.  I used a large soldering iron, about 1" diameter, some bakers soldering flux and some plumbers solder, clean it up really well beforehand.  Paint with the flux, heat with the soldering iron and let the solder flow in.  I did mine about 2 years ago and it is holding up well.  I wouldn't braze it because it puts too much heat into the tank and could warp the tank and make it hard to get a good paint finish.  Lucky is scared of welding anything other than new steel, but I'm always very cautious about applying heat to a bike tank because all the nooks and crannies can hold fuel even if the tank has been thoroughly cleaned.

[VTCBike750]

Do not weld on gas tanks!!!

Oh yeah not gonna do that. Ive never done any of this, but read enough to know this one. I dont want it to disintigrate.

I had a few holes in my tank, up to about 1/4",  I used lead solder to fix mine.  I used a large soldering iron, about 1" diameter, some bakers soldering flux and some plumbers solder, clean it up really well beforehand.  Paint with the flux, heat with the soldering iron and let the solder flow in.  I did mine about 2 years ago and it is holding up well.  I wouldn't braze it because it puts too much heat into the tank and could warp the tank and make it hard to get a good paint finish. 

It sort of seems that since I dont have an oxy acetylene torch it seems soldering may be a better option. Theres just as much about brazing a tank as there is soldering them on this forum. Im gonna run by Lowes to see what they have.

[orange550]

I might need to buy a torch to heat the cases if I ever get to swapping out the studs. But would a MAPP torch be too much heat on the cases?

Anyways, I think its something I can do. Id rather learn how to do it and have the stuff around too. I guess it comes down to whether I can find someone who can do it or whether its worth it for me to invest in the equipment.

Do you have a local welding shop? Some small joint that does hitches and stuff? Go there, and I bet they'll braze it in about 30 seconds. Just wash the tank a bunch of times with hot soapy water. Rinse & repeat often. This is easy peasy.

[mono]

a MAPP cylinder torch would be able to handle brazing the tank, if that's the way you want to go.  however, i would vote for solder if you're set on filling the hole with metal.

the reason being that solder requires a lower temp to flow, and brazing will require the tank metal to get cherry hot, which upon cooling will leave you with a soft spot on the tank (you'd be pretty much annealing the steel).  soldering should not have that effect.  also, less chance of BOOM.

[VTCBike750]

Just talked to a welding shop in town, they recommended a tank patch kit first. He also said that soldering it might fail. Apparently solder doesnt like gas?
Also talked to a paint shop who says they might be able to do it.
One guy wanted to weld it and grind it down???

If I were to solder it myself, what should I buy? I have no clue about what gas or solder to buy. Butane, Propane, MAPP?

[VTCBike750]

I did find this old thread:
http://forums.sohc4.net/index.php?topic=51719.0

Recommendation was to use either silver solder or regular eutectic lead solder. But it was said that for a newbie regular eutectic lead solder was easier.
And then theres flux, Kester Acid Paste Flux from the sounds of it.

[jamesb]

when i worked at a auto electric repair shop we had to solder feild coils and sometimes a very hard to find armature what we used was a battery charger (has to be heavy duty) and the carbon tube from a d cell battery. take the ground clamp it to your what ever your going to solder then take the carbon piece put it in the positive clamp from the charger and wa lah you have a heavy duty soldering gun,tip whatever you want to call it. when you tuoch the grounded surface of what you are soldering the carbon tip get white hot and heats up the metal extremly fast. better than a torch in my opinion

[Don R]

A sheet metal shop will have a large soldering iron, the required flux and solder. fuel does not react with solder as far as I know. It can be done without flame or arc. i'm not a fan of pour in liners but my bike has one and so far no problems. I've run race gas and gasahol without any problems.

[lucky]

Do not weld on gas tanks!!!

Oh yeah not gonna do that. Ive never done any of this, but read enough to know this one. I dont want it to disintigrate.

I had a few holes in my tank, up to about 1/4",  I used lead solder to fix mine.  I used a large soldering iron, about 1" diameter, some bakers soldering flux and some plumbers solder, clean it up really well beforehand.  Paint with the flux, heat with the soldering iron and let the solder flow in.  I did mine about 2 years ago and it is holding up well.  I wouldn't braze it because it puts too much heat into the tank and could warp the tank and make it hard to get a good paint finish. 

It sort of seems that since I dont have an oxy acetylene torch it seems soldering may be a better option. Theres just as much about brazing a tank as there is soldering them on this forum. Im gonna run by Lowes to see what they have.

Yes I agree about the soldering option as opposed to a dangerous and expensive welding option.

Oxy-actylene welding for brazing has particular requirements I will not o into but the flame of the torch needs to be adjusted for brazing.
The reason that welding on any tank that has had gas in it is that now matter how well you clean the tank when you heat the tank to RED hot the gas in the fabric of the metal makes gases that expand and can cause a explosion. Even if you have the lid off of the gas tank. Many people have been hurt trying to do it. Injuries range from burnt hair, burns on the face or hands or worse. Even though the person thought they had cleaned the tank spotlessly.


If you solder the gas tank you need to get a large style soldering iron. Rosin core solder and acid in a can with a brush.  The Eastwood catalogue would have most of the items you need with excellent video instructions too.

[mrkaylor]

This is a little redneck and probably not a long term solution but jb weld actually holds up fairly well in this situation.

I had a teeny tiny leak in a much newer gas tank (with nice paint that I didn't want to screw up), the hole was in a spot that wasn't visible so I thought before I spend a bunch of money fixing it I would try some JB weld and if it didn't work, oh well, I would just do it right then, but it's been about 5 years and the jb weld is still there not leaking.

Michael.

[NewOldSchool]

May not be the recommended way, but I had a small pinhole in the bottom of my tank once as well.

Drained all the gas and let it dry out for a week, sanded the surface around the pinhole and made sure it was totally clean of dirt/paint/gas residue, etc.

Put a 1 inch square patch of JB Weld and let it fully cure. Then put another slightly larger patch over that, again letting it completely cure.

Its held now for 2 years and 15,000 miles with no leak.....


This is more of a band-aid than a fix, but it has held.

[Don R]

There used to be a two part epoxy putty that worked well. It was available in auto parts stores.

[afkrejci90]

This is a little redneck and probably not a long term solution but jb weld actually holds up fairly well in this situation.

I've used it to repair a leak on a high pressure fuel line for a demo car.  Still holding strong for this season.  So far I can tell its fuel resistant.

[VTCBike750]

Ive thought about JB weld. Have some in the garage, but if I did that I would then line the tank. Basically take the band-aid and make it a little more permanent.

As far as soldering goes, You think regular eutectic lead solder, electrical 60/40 solder, or silver solder is the best on our tanks. Ive had a few people mention that solder doesn't like to stick to steel

I was thinking of soldering it with a propane torch instead of a soldering iron. Good, bad?

[rhinoracer]

A propane torch will warp the sheet metal.

I've soldered galvanized steel witn a large (about 7/8" diameter) soldering iron by the method described by lucky, but no tanks.

A radiator shop soldered a gas tank from a VW bug that had lots of pinholes using a torch and lead solder, it never leaked again but I didn't care about warpage on that one.

If you have a propane torch you can sharpen a round large piece of metal and heat it with the torch to make yourself a soldering iron. That's how most of them work anyway.

Either way you're giving this more thought than it deserves, try any of the methods suggested and if you don't like the results try another one.

[VTCBike750]

Either way you're giving this more thought than it deserves, try any of the methods suggested and if you don't like the results try another one.

I think you hit the nail on the head

[billingstitan]

Had several pinholes in my CB550 tank - including a 'gash' that was about 1/2 inch long, and just wide enough to slip the tip of a pen knife into...

After much research and talking to radiator shops, etc., I was not getting the feeling that soldering alone was not necessary tons more reliable than a good quality patching compound and sealer. All of the tank repair shops indicated that they would seal it with Red Kote or similar after soldering anyway (FULL DISCLAIMER: I AM NOT EXPERIENCED WITH METALWORK, JUST TAKING THIS FROM WHAT THE GUYS AT THE SHOPS SAID).

I finally settled on using Caswell's epoxy liner, along with their epoxy tank patch http://www.caswellplating.com/restoration-aids/epoxy-gas-tank-sealer.html

It has been about a month or so and has held up very well (so far), especially considering the amount of patching that was required. You basically put on the patch, and then pour in the sealer, so it actually acts as a sort of 'double patch'.

I did loads and loads of searching and did not run across any negative stories about Caswell products.

That said - I did buy another tank that I am going to refurb because I want to have a solid tank - but I do trust the tank that's on there now.

The original tank needed new paint anyway, and had a small dent - so I mainly got the new tank becuz I didn't want to put the money into decals, supplies, etc. when I knew it was patched. If it had solid paint I would run as is and just continue to keep an eye on it.

And buying a new tank and refurbing gets way expensive way fast - even DIY, and it's still pretty tough to guarantee your not going to run into more pinholes 

I just cleaned out this replacement over the holiday, and have decided to line it with Caswell's as well. It had some spotty rust which did come off without developing any leaks - but those tanks are so thin anyway, it seems that the Caswell's is a good insurance.

I have not used the other liners - but from what I have read - the Caswell's definitely seems a lot simpler to apply to the tank. The tank still needs to be clean and dry, but some rust will not harm adhesion (in fact, it is supposed to aid with adhesion - who knows?).

I also really like the concept of an epoxy vs. an air-dry product.

I might have tried the soldering if that was in my skill-set - I mean I can manage a plumbing fitting - and it may well be more solid than the epoxy patch - but thought I'd share my experience/solution with you   

[fmctm1sw]

when i worked at a auto electric repair shop we had to solder feild coils and sometimes a very hard to find armature what we used was a battery charger (has to be heavy duty) and the carbon tube from a d cell battery. take the ground clamp it to your what ever your going to solder then take the carbon piece put it in the positive clamp from the charger and wa lah you have a heavy duty soldering gun,tip whatever you want to call it. when you tuoch the grounded surface of what you are soldering the carbon tip get white hot and heats up the metal extremly fast. better than a torch in my opinion

Can you expound on this?  What part is the "carbon tube" of a battery?

[jamesb]

when i worked at a auto electric repair shop we had to solder feild coils and sometimes a very hard to find armature what we used was a battery charger (has to be heavy duty) and the carbon tube from a d cell battery. take the ground clamp it to your what ever your going to solder then take the carbon piece put it in the positive clamp from the charger and wa lah you have a heavy duty soldering gun,tip whatever you want to call it. when you tuoch the grounded surface of what you are soldering the carbon tip get white hot and heats up the metal extremly fast. better than a torch in my opinion

Can you expound on this?  What part is the "carbon tube" of a battery?

it's acually called a carbon rod  all batteries have them aa,aaa,c,d. when i posted that i couldn't remember the name of it.it's a pretty good soldering gun i've solder a bunch of stuff with it. you have to use a heavy duty charger with jump start on it. the brand we used was associated they make them for snap on and mac tools. it's funny when someone would bring them in to get repaired they would comment on how the snap on was better than mac or vice versa,and they where the same brand when you took them apart everything was just like the other it was the out side that made them different. but anyway carbon rod take one apart and it's the very center of the battery.

[Irukandji]

jamesb:  Do you need to take any EXTRA eye protection to weld with the carbon rod? I remember that movie theater projectors used (maybe still) carbon arc to light the film and it was Intense.

[Retro Rocket]

Despite all the nay saying tanks can be welded, its done all the time but you need to know what you are doing.  The next best thing is to take it to a radiator shop and either have them braze or solder it up for you, they are usually very good at doing this sort of thing..