fuel tank leaks

[Green Hornet 88]

I have 2 series fuel tanks that I thought id check and repair while out of the vehicle . I Filled them both up with water and have found a small leak along the tank and the rock protector on the one tank and a few very small leaks along the seams where someone had attempted to fix with solder already.  On the tank with leak between the tank and rock protector should I just fill the seam with solder or use something like JB weld? or remove the rock protector and fix the tank its self (solder or JB weld) and re-attach the rock protector? On the 2nd tank clean off the old solder and re-repair with solder (or JB weld) or just continue a repair around the already existing solder repair? Cheers Craig

[Matt H]

I've tried solder repairs, tried liners, tried paint on fillers and tried JB weld on series gas tanks. None worked to my satisfaction. They all still leaked eventually.

Other than replacement the only sure way to fix leaky Series gas tanks is to cut off the bottom mounting/skid plate, clean it up, cut the remains of the old gas tank floor off, build a new one and put it all back together.

My 2c.

[binch]

That actually sounds sensible Matt  ;)

[camo388]

I'd do as Matt says for the tank that is leaking between tank and skid plate.  With the Lightweight tanks I have, the skid plate is soldered to the bottom of the tank so should be easy enough to separate.  With the 110 tank it appears the skid plate is stuck on with epoxy cement so you could reattach skid plate that way.  However if in the future you need to repair the tank again, the solder will separate easier.  Unless completely sealed the skid plate allows moisture and dirt between it and the tank and the wet dirt only encourages rust to develop.
As for the tank leaking at the seam, remove old solder and CLEAN seam thoroughly.  If possible buff/ sand paper leaking area shinny clean and use plenty of flux when
re soldering. 
You won't be able to mig or braze over solder joint as solder will interfere with weld and you will have more holes than what you started with.  With mig welding the material needs to be CLEAN, CLEAN and more CLEAN as even a light film of oil or a bit of paint will smoke and thus break the shield gas envelope and your weld becomes Swiss cheese in looks and strength.

[Green Hornet 88]

Hey Guys thanks for the great information, ideas and suggestions! Looks like a project for one of those cold rainy days on the ranch. As I have them out and accessible its worth the the time and effort to do it right, might as well por-15 them as well.  Well gonna have to think way back to my high school days taking industrial arts (IA, for you old timers) on how to solder...thank goodness for Utube and not my memory! Cheers Craig

[Green Hornet 88]

Hey Guys I did as was suggested on the forum and removed the ' guard' from one of my fuel tanks I found that it wasn't just soldered on but also spot welded! I got the 'guard' off but ended up with more holes (at the welds) than I wanted.  My question to you fellow members is should I just junk this tank or see if I can get it welded up? I was thinking of removing the bottom part of the tank and weld the guard to the tank and the guard would be the new bottom of the tank.  Any thoughts?

[camo388]

Knowing the shop rate for welding, at least here in an oilfield town, it would most likely be cheaper to get a new tank.
If on the other hand you can do your own welding, I'd suggest you try to re weld/solder/braze holes then make a new bottom that will overlap any previous holes. 
Weld/solder/braze this new bottom/ guard and you should be good to go.  I'm thinking by re welding old bottom then cover everything you will have in effect a double bottom tank.
You could weld the guard to the tank to make a new bottom but then consider a separate skid plate to take the abuse of the trail.
If you solder hole repairs and new guard I'd then fit a skid plate as solder may not hold when put to the test between a rock and a ton of vehicle.
I'll be doing a similar repair to the bottom of one of my fuel tanks and thinking of MIG new bottom and guard.  New bottom will end inside the tank side welds and guard will extend to outside of tank side welds.  The welds are where side and bottom come together so thicker and should take weld heat for good penetration.  If MIG doesn't work on old tank material, my next option will be to braze.
I have one of these to add to the tank top for my diesel return line.

Bruce

[Red90]

If you can weld, just build a tank from scratch.  It should be much better with no need for extra skid plates.  If not, just buy one...