One fluid leak begets another

[lesabre400]

Got the new master cylinder installed no problem, pads looked good, made a quick repair of the leaking line with some flexible tubing, bled the brakes and drove it to my mechanics using the gears and handbrake to stop (just in case). They're replacing both lines that run to the back (the fronts seemed ok). $200. Of course while they're under there they discover a fuel leak above the tank. I could smell fuel while I was under the car on the weekend, but never saw a drip. I'm guessing its leaking from the line as it bends to go into the top of the tank? I'll drop the tank soon and investigate, but I'm hoping to be able to fix this with flexible line and/or epoxy (a la Monster Garage). Anyone else had a fuel leak in this location? Is there a common spot that goes bad so I know what I'm looking for?
Thanks!
By the way, if you haven't changed your brake fluid in a while, go do it now. The stuff that came out of my lines was black. Not good. With a new master cylinder and fluid, it should stop on a dime now (maybe a quarter). I read a post saying new rotors are cheap - that may be next. Mine are kinda ugly.

[GTSSportCoupe]

Sounds like you are going through very similar things to what I went through with my 86 tercel after I bought it this summer. I had similar brake/fuel problems. My fuel leak was from where the lines bend to go into the tank. They are actually welded into a cap that bolts onto the top of the gas tank. There are rubber hoses running from the tank lines, to lines that run along the underside of the car to the engine. I thought I'd get away with just changing the cap/lines, however when I took my gas tank off, and started scraping the rust off it so I could repaint/seal it, I found that there were actual pin-hole leaks under all the rust flakes. So I ended up just getting a whole new tank from the wreckers in decent shape. I cleaned it up really well before re-installation, and painted it with multiple layers of tremclad, and then sprayed it with asphalt undercoating for good measure. I also sprayed the fuel lines and brake lines to prevent future rust issues.

Hopefully you don't have to replace your entire tank.

[Adelard of Bath]

I just did this too! the fuel....I don't think anyone's car is as rusty underneath as mine so your's might not be this bad....I dropped the tank to fix a leak, and found many leaks in the tank....some time cleaning it showed me where I could push through with a screwdriver. So I couldn't/didn't want to find a new one, so I cleaned the metal up nice and shiny, and then fiberglassed the whole thing! It's awesome!

The rusty areas were only a problem where dirt/etc had built up on the tank, on the upper surface....surely it absorbed moisture and sat there. Perhaps the same salt-solution that the rest of my car was bathed in

But in the process of removing the tank, one of the three tubes that go into the tank broke off. Don't remember which one....so I measured the tubing and it was 1/4" O.D. so I took my supply of copper tubing in that size, and cut/bent a piece to be an exact replacement, drilled out what was left of the old one, cleaned up the area, and soldered my new piece in! Just some simple plumbing, really....since the original tubes were brazed in, if you clean it up you can find the brass in the round piece of metal that screws to the top of the gastank. Drill it out carefully so it fits snug and solder away!

Then I put it back and it leaked worse than before....so the lesson HERE is ALWAYS replace those little pieces of hose with new hose.

Then it still leaked...so then I found a tiny TINY pinhole in one of the OTHER tubes, this time the one that is the fuel pickup....the one that goes to the bottom of the tank and has the prefilter on it...I had to use pressurized air to find this one. this tube was more complicated to bend to shape heh and I don't think I got it right cuz when I filled the tank up to the top (after it finally didn't leak for a few days) the fuel gauge only went 2/3 of the way up, I think the float is hitting one of my bent tubes that I dind't get quite right

So I dropped the tank three times I guess. Dropping it really isn't too hard, putting it back up can be annoying....if you drop it, my advice is to use up as much fuel as you can ( i ran it in the driveway idleing, but that thing ran for hours and hours and HOURS so I gave up) and remember
REMEMBER
to disconnect the wires for the gauge, as found in the cargo area under the carpet under that piece of metal that has rusted screws. again probably just my car.

The first time I did it, I dropped it down onto my chest and then disconnected the hoses on the tank side...the second time I disconnected the hoses on the car-side BEFORE i dropped it, that was easier...then I replaced all the hose anyway remember to do that or you will be sorry! and I put new clamps on too

OH OH and whatever you do, when you unhook one of those hoses, your left shoulder will get a nice gasoline bath so make sure you wear something really nice under there, like a suitcoat maybe? and wear it inside when you are done and pretend not to know what they are talking about. And the second time you drop the tank, and unhook that hose, you will be ready for it....and still get a nice gasoline bath in the same spot on your left shoulder...so make sure you are wearing a DIFFERENT suit or something.

[Typrus]

My dad had a whole 4 gallons of fuel gush onto his shirt then pants when he took his motorcylce tank off the first time. One of those moments where you stumble for 2 minutes trying to figure out what the hell is going on then realize you forgot to turn the valve that cuts fuel flow. lol. He played like he didn't know what we were complaining about, until his head started hurting then he went and took a shower.
Something rather entertaining- those 2 dead Tercs both have good fuel senders. Tomorrow I'm stealing the silver ones sender.

[lesabre400]

Thanks for all the tips, Adelard!
I'm not in a big hurry - I figure it's a can of worms that doesn't need opening until I can actually see a leak happening. Nice to know what to watch out for when I get to it though.
Thanks again, guys!