Soldering Fuel Tanks

[Tony Smith]

I have one good straight rust-free fuel tank with the filler neck removed, and one battered fuel tank with a good fuel filler neck. How do I go about soldering the good neck on to the good tank?

All the people I know who are adept at soldering (Plumbers and Electricians) just give me a blank look when I ask about soldering steel to steel, as they're more used to working with copper and brass. Is there a particular type of solder alloy I should be looking for? What should I use for flux? My small Soldering Iron won't be sufficient for this job, would a low Oxy flame be too hot?

It has been quite a while (years) since the tanks have held fuel and there's not the faintest whiff of petrol vapour from either. I've cleaned out the tanks with POR15 metal cleaner, a handful of gravel shaken vigorously, then another rinse out with POR15. Do I need to fill the tanks with water to prevent a Whoompf event, as I feel the water will act as heat sink and prevent a good soldered joint?

[Rolf S. Ask]

My guess is that those two tanks should be different from the day of birth.
The one on the left I think should have s small rubber tube and then an other steel neck to go on top of it again.
I am not sure, but think so. Or those with the rubber tube is located a bit more on top of the tank, can't remember, have to check in my garage...

Rolf

[cletrac (RIP)]

I've found that if you're going to use a torch around a fuel tank it's a good idea to run a hose from an exhaust pipe into the tank. The exhaust displaces the oxygen in the tank and prevents explosions. Keep the engine running until you're finished with the torch.It doesn't seem to matter how good you clean the tank there's still fuel residues in the folded seams in the tank.

[Alex Blair (RIP)]

LOw temperature solder ,650F...17,000 pounds tensile strength should do it..Can be used stainless,steel to steel, steel to copper,or any combination of the lot Called Stay Bright #8...High percentage of silver...
Special paste flux..
See your local refigeration supply house..They handle it//
Have lots of money in your pocket when you go..
Other wise just braze the neck on with brass,pre pasted Eutectic Silver....or arc it on ..MIG..TIG...stick...7018 or 7024 make a nice clean weld but an air craft heli arc welder would do an amazing job..Don't have an aircraft repair shop in your back yard..??

[greg anderson (RIP)]

As one who has had the experiece of being blown across the room while trying to solder a long long unused gas tank which also resulted in the end being blown out of the tank I endorse the advise above to run your exhaust pipe into it while working.Then when people ask what is wrong with you you wont have to explain--like see there was this gas tank etc.--Greg

[Snowtractor]

...buddy of mine welds on fuel and diesel tankers nightly. They steam the tankers a min of four hours to remove all trace of explosive gases. They test it before and after with a explosive sniffer. They have never had an explosion.
Just a thought
Sean

[Bob Moseley (RIP)]

Tony

I'd hate to see your hat without a head. Take it to your local radiator place and get them to do it. Thats what we do here.

Bob

[Bob Carriere]

...and blow yourself up......could you share your experience with the POR????

I will be facing the same problem as you encountered..... my tanks may actually need a metal patch to cover the rusted hole loctaed behind the holding strap.

I want to coat the inside as well BUT what I have been able to see trhough the hole has me concerned. The tanks seem to have baffle plates made of perforated steel...about a quarter inch holes with two such baffles...... and enough loose rust to vuild another tank. How much of a mess did you make.... I have used POR paint before and know from expereince it takes 3 weeks to wear off spills off your skin......

I have used antique car gas tank coating that looks like a white rubberized coating on old tractor gas tanks with no baffles... had excellent results even sealed the millions of pin holes in the tanks.

This white stuff I used could be poured back in a can for future use..... I bet POR would hardened way to quickly for that. Did you use the full quart....??? Or come to think of it is it the special tank sealer that POR sells which is different than the paint POR???

Thanks for your comments.

[Tony Smith]

Bob, the POR products I used was "Marine Clean" and "Metal Ready" to clean the inside of the tank. I then used about 3 handfuls of fine blue metal gravel ( from a handy roadside stockpile ) and shook and rotated the tank for about 5 minutes. After shaking out the gravel, I then washed out the tank with water and gave another treatment of "Marine Clean" and "Metal Ready". The inside of the tank is now immaculate! Shining a torch inside reveals steel that looks brand new. POR also have a fuel tank sealer product that will seal pin holes and the like, but I don't require that in this case.

I don't know if this is of any help or not. Roughfly 30 years ago I had a chat with a mechanic who served in the RAF. He said that the way that they handled gas tanks was to clean the site of the puncture etc up and put some flux on it then heat the end of a bar of solder and jam it into the puncture. Given the present discussion I don't know if this would work or not.

[Mike Kelly]

I know that professional abrasive blasters will not , under any circumstances blast old fuel tanks , no matter how old .

I think filling the tank with water sounds safe . I have heard of the exhaust gas idea too .

The normal hardware store solder sticks used by plumbers etc. will work fine on steel to steel . First , you have to sweat off the old neck , maybe a old fashioned soldering iron would do it , those pointy things with a wooden handle you heat up . ( like in metalwork at high school ) . This method would be safer too, as no flame is in contact with the tank . If you do use a flame , use a small LPG type torch , a oxy flame is way too hot . For flux , BAKERS soldering fluid is fine , or any of the common fluxes sold at a hardware store . You may have to re - tin the neck with new solder . Is the neck held in with any mechanical devices ? e.g. rivets . As some structural strenght is needed to provide some rigidity .

Another alternative is , make a new tank . Just need some 20 gauge galv sheet , some sheetmetal skills. a few pieces of sheetmetal gear e.g. guilotine and folder ! It can be done , but its tricky and takes lots of time . The raw material is so cheap , it doesn't matter if you stuff a up a few prototypes . To make the ends , you use a hardwood die , you dress the steel around the corners /edges . Its amazing what you can do after some practice. I have heard of guys making new tanks out of copper .

I have to make two new tanks for a Morris CS8 , they are round , this makes it a somewhat easier task than making CMP tanks . There was,a fellow in QLD , Peter Fraser , who makes first class Jeep petrol tanks , and any other type you desire , but , for a price .

Mike