Gas leak - what caused this?

[Christien]

I just fixed a gas leak in the bottom of the tank yesterday, and I'm stumped as to what might have caused this. It was a slow drip at first - you could smell it in the driveway. But when I got underneath the car and wiped the area with a paper towel to see where exactly the leak was, it started spewing out! Turns out there was a 1/4" hole in the bottom and the flow was just being stopped by debris, dirt, etc. It's a wonder the entire tank didn't empty out on my driveway!!

Pics:
Closeup of the hole:


A little further away:


A sight you never want to see!!!


(yes, this is how I drained the gas tank. Luckily there was only about a quarter tank in there.)

Chris

[Blondie]

Moral of the story:

...never fill up beyond a 1/4 tank.

[67l60]

time for a new tank

muat love rust and age

[Christien]

Can rust eat a 1/4" hole and not leave any trace on the surrounding metal? There's no rust to be seen anywhere else on the bottom of the tank, especially right around the hole - it was all shiny once I wiped the dirt and crap off it.

It actually looks like a bullet went through it.

[SoCal Driver]

Or an ice pick or other sharp round tool like an awl.

Most likely something kicked up from the road.

[67l60]

butt yes gas tanks tend to rust from the inside out
seeing how there is undercoating on the outside

[Dantilla]

I stopped a leak in my sister's car several years ago with some gas sealant from the local auto parts store that hardens when it comes in contact with gas.

Just stick it into and around the hole like putty.

[Christien]

Yeah, that's exactly what I used. It really didn't want to stick to the metal, though, so I'm keeping a close eye on it for the first few days.

[JonA]

2 part epoxy and a little piece of fiberglass cloth. Works great. Easy fix now that the tank is empty. Read up on how to safely work on the tank first.

Jon

[onZedge]

Originally posted by JonA
Read up on how to safely work on the tank first.

What happened?

[Razorback1980]

LOL...yeah, I want to hear that story too!

[Eldorado]

i think he's basically saying dont weld anything to it if there's vapour in there :P

[magilla gorilla]

Originally posted by JonA
2 part epoxy and a little piece of fiberglass cloth. Works great. Easy fix now that the tank is empty. Read up on how to safely work on the tank first.

Jon

When I fill up my tank , I have a strong gas odor until it drops below the half way mark.. I,m thinking the seam is leaking, Any thoughts on this??

[JonA]

I don't have any good stories about blowing up gasoline tanks and I don't know exactally how you make them safe to work on but I have done some pretty dumb things that I wondered about after. A tank empty of liquid but full of fumes is a bomb. Gasoline fumes are heavier than air and will stay in the tank. Even cleaning around a tank hole to prep it for epoxy can cause a spark and then your Porsche looks like it was last driven by a Baghdad suicide bomber. There is a proceedure for venting the tanks that maybe others on this site can help you with.

Jon

[nynor]

Originally posted by magilla gorilla
When I fill up my tank , I have a strong gas odor until it drops below the half way mark.. I,m thinking the seam is leaking, Any thoughts on this??

this is probably something to do with your fuels lines, or the filler tube, or the return line. may also have something to do with the charcoal canister.

[badjones]

Anything that causes sparks near an empty fuel tank ( welding, grinding) is extremely dangerous. Fuel vapour is explosive. To make a permanant repair the tank needs to be removed and flushed with water to remove liquid fuel fully, and then have a patch welded over the hole or braized over the hole, whichever you prefer. PLEASE NOTE. To make the tank safe to weld you need to purge the tank of fuel vapour and the easiest way to do this is to run an tube from a car exhaust into the removed and flushed fuel tank ( must be done outside of course) and run the car for a few minute just before you attempt the repair, and this will purge the tank with a non flamible gas. I always check the tank opening with a lit match at arms length after gassing to make sure all is well before you get close up and personal with the mig welder. I have done many tanks from mainly bikes but cars as well useing this method. For emergency repairs to get you home, mix some ordinary soap with some sand and knead to a firm putty consistancy and plug up the hole with that. Have used this one in the outback down here many times much to the disbelief of those who needed the help. Accidentally sold a car once after doing the soap repair two years earlier and forgot to fix it cause it never let me down. You learn some handy stuff living in the outback. Good luck.

[Razorback1980]

That soap and sand thing would concern me...never want sand anywhere near my gas tank. Might work, but I think I'll try other methods first. I admire your courage to weld a tank...I would be too scared and would just buy a new tank. Thankfully, there are other people like you that don't share my fear.

[Hoss Ghoul]

Originally posted by nynor
this is probably something to do with your fuels lines, or the filler tube, or the return line. may also have something to do with the charcoal canister.

That narrows it down...

I have the same damn problem, I just live with it.

If the fumes are from the front driver side, it is the charcoal canister.

If it is coming from the engine bay, check your fuel lines, this should be obvious.

If it is from the rear it is the filler neck or the rear fuel lines. Mine is from the rear, pulling the rear carpet revealed nothing, likely it is the filler neck...PITA, not worth fixing to me.

[badjones]

The sand trick may very well save your life if you are out in the scrub, and is only a method used when there is no other choice. It's an old outback survival trick. The sand is only a small percentage of the sand/soap putty and is held in the mixture. Try it on an old heap and see the result. As for welding, its safe and necassary if new parts are unavailable or too expensive. We pay a fair bit more for our second hand parts over in Australia I think.

[jwade944]

The metal tanks develop a stress crack on the top of the tank. I replaced the tank on my 924S race car several years ago and the used tank I bought had the same cracks. I bought an epoxy product from Permatex at my local auto parts store and have never had any more trouble with it. The symptom was gas odor when the tank was above 1/2 full.