CMitchum

New here, just bought a 1965 Delta Holdiay Coupe, 425 4 bbl., soooo cool. She's a survivor. Nearly all original parts (read: old) with only 54,300 miles.

Anyway, seems I have a leaking gas tank when over half full. Several thoughts occur.

Leaking at the weld?
Leaking at a hose connection up top?
leaking from a rust hole higher up?

I will be dropping it (only way to be sure) to check.

Preparing for the worst, I started searching for a replacement tank. Could not find any for this application. I'd rather not have a repaired tank unless I have to.

Does anyone know of a manufacturer or distributor that might have this tank?

jaunty75

I doubt that you'll find a source for a new one for the full-sized cars. They're just not made. If you had a Cutlass, yes, but not an 88. If your tank can't be fixed, you'll need to find one from a junkyard car.

lshlsh2

I willing to bet that you have a leaking vent line or fuel line. 40+ year old fuel line starts to fail. Happened to me on my 71 cutlass. It would leak when I turned left . Bad vent line was an easy fix. You don't have to drop the fuel tank to fix. I did I wanted to check the tank over.
Larry

jaunty75

But if it was a leaking vent line or fuel line, why does it only leak when the tank is half full or more? To me that suggests a weld that's opened up. The typical tank is two halves welded together, and if the weld opened up anywhere around the circumference of the tank, you would expect exactly what he has observed -- the tank leaking when it was about half full or more.

Or, it could be a leak where the filler tube meets the tank.

Below is a photo of the tank out of my '67 Delta 88 when I had it out of the car to fix the sending unit. Look at that big seam running all the way around the tank where the two halves join. That's where I'd look first for this leak.

Note also where the filler tube meets the tank. It's right above the seam. If an opening developed anywhere around where this tube meets the tank, it would also leak pretty much only when the tank was half full or more.

One question is, does it leak while the tank is being filled? If so, that might suggest a filler tube problem.

Oldsmaniac

I think on the 65 the sender assembly is at rear of tank and not on top so the gasket could cause a half full leak....

lshlsh2

Mine leaked bad when full less as the tank emptied. At about half a tank it stopped. If it is a hole or a split seam it will leak to that point and you will end up with a puddle of gas under your car. It could be that but I am still betting on a bad line. At least hoping that he does not need a tank. If it is a bad line it will leak when the car is moving not still. A hole will leak as long as the gas is above the hole.
Larry

CMitchum

Thanks guys. I am leaning toward the weld; yes all OEM tanks i have seen are two halves welded. Part of the weld line was wet when it was leaking but i couldn't be sure it wasn't from above. I had the same thought about old brittle lines. In fact one on the fuel pump was bad. (Actually the fuel pump was bad too, I later found.)

So I'll drop it and see what's what then post some pics and results.

Olds64

You can probably take the fuel tank to a shop to be cleaned and repaired. There are also do-it-yourself repair kits for fuel tanks. I'm not sure how well they work if your tank is leaking though.