Replacement fuel tank creating problems?

[bones66]

A couple of years ago I replaced the fuel tank on a diesel MF-230. MF no longer made the tank so an aftermarket tank was the only option. The tank was identical in size and shape to the old one as far as I could see. The only difference being the new one had the fuel return line in the front middle about half the way down the tank. Right in the battery box. The fitting on the tank protrudes out nearly an inch and then a new return line was fabricated and a 90 degree bend was put into the line to keep it out of the box as much as possible. My old battery barely fit but I'm not able to find a new battery that will fit. 3/4 of an inch longer and it's a no go. Interference with the fuel return line and fitting. I actually still have the old tank and the old fitting is just soldered on. I actually took a small propane torch and removed it today. I would like to put the old fitting on the new tank in the position it was originally located then close off or remove the new one getting it out of the battery box area. Has anyone ever done any soldering on a fuel tank? What is the safe procedure? Anyone got any other solutions. I'm sorry if i didn't explain this well so if you have questions fire away. Thanks in advance!

[CharlieS]

just dont use a flame to solder on any fuel tank. The couple of tanks i've repaired I use a big soldering copper and torch heat it away from the tank.

[Gary Fowler]

Assume that you have remove it, so I would just rinse it with hot soapy water to remove the diesel and leave the cap off. Use a small brazing tip and solder as if it were any empty tank. If properly rinsed, it should not have any diesel in it but it still migh produce some oily smoke from the heated area but it shouldnt be enough to ignite.
Pressure test the tank repairs with low pressure (5psi ) air to check for leaks then dry thoroughly and reinstall.

[Soundguy]

ditto what gary said.

heck.. I soldered a new fitting onto the bottom of my case VAC GAS tank a while back.

soapy water did the trick...

[bones66]

Dag gone it!.....I used to have one of those big copper soldering irons but I haven't seen that thing in years???? so that idea is probably out the window! I though to myself I'd never use it. For you fellows that used soapy water how did you get all of that out of the tank. Didn't know if I was going to get any responses from the forum so I ran out and talked with an old mechanic I trust. He advised to drain the tank and blow it dry then go for it. He said diesel is not a problem and he's fixed many. Actually has fixed some with a small amount of diesel residue with no problems as it was in the opposite end of the tank and he brazed it! I think his dangle downs are bigger than mine!

[Soundguy]

i used a soap, soap. ie.. somehing like purple power in the tank.. and then more water flushing. at the end, i dumped in a pint of 90% rubing alcohol and sloshed it around and dumped out and let evap.

alcohol is a polar solvent.. grabs water.. easy to evap when solvated.. not a problem in gas or diesel like that.

[bones66]

Well, I got my tank all fixed. Being a little hard of head and not being able to find anyone that might be able to do it for me I drained the tank, re-lit my trusty propane torch and got out some solder. Got it looking pretty good with the exception of one little spot. Well that little spot did seep as I noticed a slight discoloration after a while ugh! Off I go (again) in search of someone to do this right. Was directed to an old gentleman who used to do this type of work but no longer. He told me you put water in them! I hadn't done that and wasn't thrilled about that idea but whatever it took to get it fixed. He sent me to another place. Another older gentleman who still repaired radiators and done other welding and only 5-6 miles away. Off I went to his place. I explained what I needed and he asked if it had diesel or gas in the tank. When I said diesel he said he would not put anything (liquid) in the tank he said Diesel is not a problem. He took care of my leak while I went for lunch and at a very reasonable price.