Are there any fuel tank repairs that will cure in the presence of gasoline? I've got a small crack (metal tank) that is seeping fuel at a rate of a drip every 5 seconds but the tank is 3/4 full and I don't have a container(s) big enough to drain it. I see that Permatex makes a repair kit but don't know if it will work on an active leak. Any advice is appreciated.

 

I have yet to see anything that will fix a cracked tank that will last longer the a couple of weeks. Your best bet is to find a new tank. Unfortunately most junk yards puncture the tanks when they get a vehicle in.

 

The Permatex stuff will make a permanent repair but it will require the area to be dry and smoothed out. I'd find something to drain it even if you end up wasting the fuel in it

 

I found an epoxy/fiberglass fuel tank repair kit that included a mastic stick. I used the mastic to temporarily seal the hairline crack. That allowed me to scrape, sand, and thoroughly clean the metal around the leak. Then I applied the 2-part epoxy, embedded the fiberglass into the epoxy, and reapplied more epoxy over the fiberglass. I'll let ya know in a couple weeks how it's holding up but it looks and feels very sturdy. If it starts leaking again I'll wait until the tank is almost empty to attempt a more permanent repair.

 

My tank started leaking last winter. Cant remember what the stuffs called but it worked in 0 deg weather with the tank leaking still holding strong. I picked it up at o-reillys .

 

The biggest problem that you may have is that you have a crack in the metal. Cracks tend to keep cracking. A puncture is much easier to fix because a puncture will not spread like a crack would. The only real way to fix a crack in metal is to drill a hole at each end of the crack the repair it. A metal tank can be welded but has to be done by someone that knows how to do it and it needs to be completely purged. It would be much cheaper to replace it with a new one. Let use know how the fiberglass repair kit work once you get it all done. It would be nice to know if something out there really work for longer then a few weeks.

 

I've set a reminder to check back with this thread an a few months with an update. All I can report, at this point, is that it held overnight. LOL.

The crack was unusual, there was minor scuffing of the rubberized tank coating in the area indicating some form of impact but the metal in the area of the crack was actually being pushed out from inside the tank. It's like that horror flick where the creepy killer is calling from downstairs.

There was a protruding rib in the tank metal that was maybe 1/2 inch long and the actual crack was about half that length and so thin you couldn't really tell it was there. If not for the leaking gas, of course.

 

Nothing like a brand new fuel tank for around $100 from rock auto. Maybe upgrade to 20 gallon tank?

 

All stock XJ tanks are the same physical 20 gal size except very latest . Some came from the factory artificially limited to 16 gal with internal plumbing that can be modified.

My '85 developed multiple rust leaks in the bottom of the tank at one point. I repaired with exactly same materials as the OP, not from a kit, but items I keep for marine work. I went ahead and ordered a new tank but never installed it because the repair lasted for the rest of the life of the Jeep.

I don't know what shipping would be but I still have the tank if someone with an '84/'85 XJ or possibly '86 MJ could use it.

 

Bar of soap rubbed on the crack til fuel quits coming out. Clean off the area real well, including polishing off soap residue on the outside of the tank. . JB Weld a nice big area around the crack. Did that 20 years ago on my old 78 Kenworth and it still doesn't leak.