I have another project vehicle, 70 Opel GT, and the Fuel tank has a badly rusted out spot. If I clean the tank out, does anyone see any problems with welding in a patch? Or should I just look for a replacement tank so I don't blow myself to pieces? I don't see a problem with welding it as long as it's cleaned out. Don't think there would be enough fumes to cause a problem. <img src="/forums/images/graemlins/confused.gif" alt="" />

from what I understand .. you'll never get all of the fumes out .. it "soaks" into the steel .

Well, just talked with the "old man", been in the gas station tank testing and construction business forever. He said NO WAY, do not weld on a gas tank, like you said, it soaks into the metal and you'll never get it all out. Only way to do it is to have a constant flow of nitrogen going into the tank. He says he had the same problem with his Opel gas tank and he just fiberglassed it, so that's what I'll do. <img src="/forums/images/graemlins/kewl.gif" alt="" />

I've heard of people filling them with water, but I don't know how effective that would be.

I'll have to check with my neighbor( a certified welder with 40 years experience), but there is probably a way to do it.

He tells stories of welding holes in propane tanks full of propane, so an empty & cleaned gasoline container is probably do-able. Not sure how much experience is required before trying, though.

Dave

>>>*I welded a gas tank once out of an old stock car we were running at the Portland Speedway. Those were the days before fuel cells were required.

The driver got into a pileup and holed the tank pretty good, it was a Friday night and we had a 100 lapper on Sunday.

I pulled the tank, it was pretty much empty anyway. I knew what would happen if I just started welding a section on so I flooded it with water and cut an access hole in the top with a steel jigsaw. It was amazing the amount of tarnish and buildup inside of it from years of use, I think that is the real problem rather than the steel absorbing fumes.

Then I dumped the fuel tank into our Hot tank filled with Sodium Hydroxide. It came out all spiffy clean and shiny.

I welded in the repairs, made a patch with a gasket to cover the big hole I cut in the top, put the tank back in and we went racing. We made it four laps before we ended up in the Blackberry bushes but the tank didn't leak...*LOL**..

I would never suggest trying to weld on one after what I saw in there, that's a good way to make loud noises. The heat releases the fumes and it could build up very quickly I think, even empty..

*But I was young and completely invulnerable back then......*EB

the old excavators, farmers, truck re-builders have always told me "weld a gas tank while its full, not empty. the fumes explode, the liquid doesn't." think about dropping a match into a gas can. the match will go out. its sounds scary as sh!t, but they are all still alive, and no burn marks on their faces.

This is a good point. Gasoline dosn't burn; gas vapor does. Hence you need air coming through your carborator or intake, else the beautifil little 22r dosn't do anything.
No oxygen = no flame.

That said, I certainly wouldn't have the balls to try it myself...

I have welded up a number of gas tanks by filling them with water. I have also seen it done by sticking a hose from a CO2 tank into the filler and turning it on filling the gas tank with CO2.

filled one with water once and welded it,..make sure it's not air tight or the steam presure will build up and find a way out,.... first one i did (was a small 1.5 gal tank)blew out. nothing like hot steam blowing your hood off your head