dropped the tank in my in-op Impulse to change the fuel pump as a first step of many in trying to bring it back from the dead. surprisingly, this was the easiest tank to drop with plenty of room to access all hoses & connectors.
the pump hanger/cover was pretty crusty so gave it a good soak with Aerokroil. I also noticed one retaining screw was already broken off. despite being as careful as possible only 3 screws came out in 1 piece, so that leaves me with 5 out of 8 broken off in the tank ring. 
trying to grab the nubs with vise grips didn't work, just further mangled what was sticking up.
soooo, wtf can I do?
trying not to do anything stupid, being a used fuel tank w/vapors and whatnot. there is enough sticking out that perhaps a nut could be tacked to each one, but see previous sentence. drilling them out: can a drill motor ignite vapors? would filling it with water enable me to work on it safely?
no new/aftermarket tank replacements available.
Filling the tank with water would likely be safe. I'd leave it open for a while to get rid of as much fuel vapor as possible first. Purging the tank with nitrogen or other inert gas should work too.
Bring it to a radiator shop many will boil gas tanks in the same vats they use to test rads. then you can drill and be safe if they don't offer to do it for you.
If filling with water prior to welding, make sure that there are no air pockets. It will go boom, and you will E36 M3 yourself. I've done that recently.
Definitely do the water purge and make sure pockets are out. Nitrogen is only slightly lighter than air and I'd be more fearful of boom with that vs water unless you have a constant flow of inert gas into it
Don49
HalfDork
5/9/16 8:00 p.m.
Old timers trick- run a hose from the exhaust of a running car. It will purge the tank.
eebasist wrote:
Definitely do the water purge and make sure pockets are out. Nitrogen is only slightly lighter than air and I'd be more fearful of boom with that vs water unless you have a constant flow of inert gas into it
Yeah, nitrogen purge would need to be constant while working (and fed in at the bottom of the tank so anything else gets pushed up and out).
Don49 wrote:
Old timers trick- run a hose from the exhaust of a running car. It will purge the tank.
This ^
I've done it a few times now and it's the easiest way.
Had to re-flow all the solder in a copper fuel tank last year and it worked great.
-edit- I've also exploded a fuel tank while welding on it so I know how NOT to do it too.
Exhaust gas is the way I've heard of doing it, like hook a tailpipe of an idling car to the filler tube, at that point you can supposedly work on while it dries out, since the oxygen content of exhaust is pretty negligible.
Most drills are brush motors, tons of sparks.
Air drill for sparkless drive. not too fast on the drill speed to keep heat down. Purge with whatever method above is most readily available. You could also slosh with acetone to help get the gasoline cleared out of crevices, and the acetone will evaporate quickly.
I am going to be doing this on a fuel tank I built that has decided to develop a weep.
with a small edit to change sparkles to sparkless!!!
