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JB weld and ?modern? gas

I?ve recently, inadvertently, dislodged some odd jerry rigging that was done on my motor home fuel tanks.

The electric fuel switch hasn?t accessed the back tank for over a year. Apparently the previous owner had the same problem and attached a pipe fitting and hose between the two tanks to create an uber tank. As it turns out, the attachment wasn’t really anchored with threading or anything, just screwed directly into the gas tank wall and spot welded or soldered, I can’t really tell.

So anyway it only took a bump and the pipe fitting came loose in the front tank (the only one I can access to drive) and gas started dripping out at a pretty good clip. Frantically but successfully I rounded up enough gas cans and emptied the tank now in the after math I am left with a main gas tank that has a pinky sized hole in it where the pipe fitting eventually fell out completely.

I can say, I’m glad this happened while parked and not on the road.

So, the plan was to pick up some JB weld and fill in the whole or find a bolt of appropriate size to act as a stop and JB weld around it to get a good seal.

I went to pick some up and was informed that JB weld no longer works on gas related repairs because our ‘modern’ gas eats through the bond… on line there are a dozen people reporting the same thing and another dozen saying it’s a urban myth…

By chance have you had any experience with JB weld and ?modern? gas?

I really don’t want to have to drop the tank but I also don’t want a ‘bad’ repair…


While I don’t have specific experience with JB Weld and the effect of so-called “modern” gas on it, I will venture that I’d never try to repair a gas tank in this manner. Maybe I’m just paranoid, but I wouldn’t be doing it.

JB weld doesn’t work for gasoline leaks. You can apply it, let it cure, and after about a week the gas will break down the bonding agents in the JB weld. At first it will just sweat gasoline, but soon after it will turn into a full-fledge leak again. I think your best bet is to use a product that’s specifically designed for patching leaking gas tanks and follow the instructions. Something such as this


There is a two=part putty designed for temporary gas tank repair. It works on all petroleum product tanks including diesel and “new” gas. REMEMBER, it’s designed for TEMPORARY repairs. And it has little structural integrity, so it should not be relied upon to hold things together.

You will, ultimately, have to do a proper repair on the tank.

thanks everyone. I will look at dropping the tank.

this looks good. and confusing…says it does permanent repair yet seems many here are saying the only way is the drop and weld…

Well, if you drop the tank, the hole can be welded closed. And that’s even better!


By the way, there are radiator shops that also advertise gas tank repair services.

This stuff outperforms JB Weld in these applications and has been around for a long time-

I’d drain the tank below the hole, clean and rough up the area around the hole, find an appropriate sized SS self-tapping bolt, generously apply the Seal-All around the head & hole and drive it in. Let it cure and you’re done.

A few years ago I fixed a leaking seam on the gas tank of a '74 Corolla with JB and it held up as long as I owned the car. I occasionally talk to the guy I sold to to, and he hasn’t mentioned anything about it leaking either-- and since that’s a car that has the gas tank in the trunk, you notice when it leaks!

Since there do seem to be products specifically designed for this, that would probably be the better bet, though.