Punctured my gas tank...

[EvoStevo]

So I was driving to work and while going through a tunnel I must have run over something. I heard a thud but didn't notice I was spewing gasoline into the street until I turned. It was literally gushing out like a waterfall. I just got it towed home, but haven't assessed the damage yet. Based on what I saw while it was leaking, I have a feeling it's not patchable. How hard is it to swap in a gas tank from a junker? My car is an '89 325is. Thanks in advance.

[Imagine_M]

ya dont put in an early tank!

And replace all the fuel lines when your there!

[Lunner]

The gas tank was one of my least favorite things to remove/install.

I'm not positive, but I'm fairly certain the subframe can stay in place. You'll figure it out real quick if you need to though, if someone doesn't chime in here.

Either way, here's something resembling a step by step (off the top of my head).


1. Remove the exhaust system, from the manifolds back, including all heat shields. Edit: Actually it might just be from the catback, if that's the case then you'll need new exhaust gaskets. And if you remove it at the manifolds then you'll need new copper nuts and gaskets there too.

2. Remove the driveshaft.

3. From up top (underneath your back seat) disconnect all the fuel lines (all of the ones you should need to disconnect will be under these access panels). Oh, and disconnect the big hose connecting the filler pipe to the tank too. Be prepared to replace all of these lines, and probably the filter too if it's been a while.

4. Remove your gas tank, drain it first to save the gas, not pollute, make the tank lighter etc. There's a little plug on the tank you should be able to find for this. There's something like a half dozen bolts holding it up, keep your mouth closed and wear goggles while removing it. Oh, and a floorjack/friend will be handy for balancing the tank while removing/installing.

5. Using a later model tank only, deal with installing a heavy/cumbersome tank into a pretty rigidly set location, struggling with balancing it and lining up bolt holes, and tackling any rust/difficult hard rubber lines you find along the way. I think the only upshot here is that you're in LA, so it shouldn't be all rusty (and a major PITA).

And here's a list of things to consider replacing while you're there, as needed (i.e., if you don't know how old they are/they don't look good). These'll all be easy to replace as part of this job.

Muffler, Guibo/Flex Disc, Center support bearing, all fuel lines, fuel filter, inner brake lines. If your fuel pulse absorber (a little bell shaped thing in the feed line) is all rusty and grody like most are then just toss it, don't bother replacing it, you don't need it and it's a fire hazard when it's rusty like that. And get new o ring(s?) for your fuel pump/level sender too.

And if you've got the interest/time/money, check the play on your driveshaft U joints to make sure they're nice and smooth (Peerless @ e30motorwerks does a good job remanufacturing them at a fair price in that area). And consider doing the rear suspension bushings too, obviously especially if the subframe needs removing.

Good luck,

-Brett

[EvoStevo]

Thanks Lunner. I took a look and it is a pretty sizable hole (just smaller than a dime maybe). Someone recommended elsewhere on the internet to use a large sheet metal screw and screw it into the hole, then JB Weld around the head. Would this be a good semi-permanent fix?

[Lunner]

Thanks Lunner. I took a look and it is a pretty sizable hole (just smaller than a dime maybe). Someone recommended elsewhere on the internet to use a large sheet metal screw and screw it into the hole, then JB Weld around the head. Would this be a good semi-permanent fix?

I'm not gonna weigh in on internet advice / shade tree techniques, but personally I'd give something like that a shot first, given the difficulty of the swap.

But if you think you need/want to replace the items I mentioned earlier, I'd go ahead and make a big project out of it. Your e30 will thank you, particularly in the subframe bushing area if those are 20 years old.

You could even figure out a quick patch job and then wait on doing all the stuff until you've got the time/funds. That's probably the route I'd take.

[EvoStevo]

Yeah, I do eventually wanna replace all that stuff but I'm just not prepared to do it any time soon. I'll give this a shot and see how it holds. Thanks for that step-by-step though, I'll definitely need that in the future I think. It's odd that tank replacement isn't really covered in the Bentley Manual.

[jlevie]

You might get away with a patch on the bottom of the tank, but then it could leak at some point in the future and result in self immolation of the car. I don't advise trying a patch on the bottom of the tank.

Replacing the tank isn't that hard, though you probably will find other things that also need to be replaced doing the job. It will be a big help to get the car well up in the air. I use six ton jackstands for exhaust, drive shaft, or fuel tank work with the jackstands extended about half way.

[Kershaw]

You might get away with a patch on the bottom of the tank, but then it could leak at some point in the future and result in self immolation of the car. I don't advise trying a patch on the bottom of the tank.

self immolation.

that's always fun.

dropping the tank isn't that hard. but when i did it, the car (or what remained of a car) was on its side. :up:

[Dude]

Cut it out with a torch!

[IminDiegoTriick]

I did the same. Replacing the tank was the worst and tedious. Simple with a car life if you can manage to get it to one, will save you a loooottt of time. Two people preferred for this job but you can do it by yourself until mounting the replacement tank.

[jlevie]

I've pulled and reinstalled the tank on several E30's by myself with the car on jack stands. If you get the car high enough in the air it isn't that bad of a job. With a helper it would be a easy, but you can substitute a bottle for a helper.

[Danny]

Jb weld.