In spite of multiple interruptions I did manage to get the gas tank out
of the Cobra Saturday. This is the second time its been out while I've
owned the car. The last time was about 15 years ago and I couldn't
remember much about that removal other than it was painful. That part
of my recollection was certainly accurate. I thought I could get it out
through the trunk opening but that wasn't the case. I had to remove the
aluminum bulkhead behind the seats and, of course, the seats themselves.
Plus a few other boring obstacles.
I put the tank on a couple saw horses, cleaned up the outside a bit and
checking for obvious damage. I also was able to remove a filler nozzle
from a gas can that had fallen into the tank a number of years ago.
>From the outside, the tank looks pretty good. There are only a few
small patches of surface rust in areas where the plating has gotten
scoffed. I'm not sure what the plating is. It doesn't appear to be
zinc; possibly cadmium. The finish is dull and the coatings is fairly
thick. There has never been any paint on the tank as far as I can tell.
The more serious looking rust is on the inside bottom of the tank but it
doesn't seem too bad to me. I haven't found any obvious cracks, rust
holes or seams that have come unsoldered. I suspect the leak is at the
exit fitting which is where it was the last time I pulled the tank.
That time the fitting was leaking around the solder joint between it and
the tank. This time the solder bead appears to be intact and solid.
What I suspect is that gas is leaking past the fitting threads. The
reason for this suspicious is that when I fixed the problem last time by
re-soldering, I got the fitting too hot and it warped. I straightened
it as best as I could but the threaded hole is just slightly out of
round. By putting lots of Permatex on the threads and using a crushable
washer I was able to keep the joint from leaking until recently. I was
tempted to try re-gooping the threads again but decided I wanted to get
the inside of the tank de-rusted and sealed this time. I'd like to
replace the warped fitting if I can find something similar to replace
it with. It's a circular brass plate about 1/8-3/16" thick with a 1"
tapped hole in the center. So far, I haven't figured out what the
thread pitch is. I do know that it's not 1-8 or 1-14. At first, I
thought it was 1" pipe but I couldn't get a 1" pipe nipple to screw into
the hole either. If I can't find a replacement fitting, I can probably
make one if I can figure out the thread pitch. Tonight I'll try the
brute force method of counting the number of threads on the fitting that
screws into the plate and measure how long it is.
The next big decision is to decide where to take the tank. Dave's
Radiator Service in Sunnyvale did a pretty good job of making a new
heater core for me but I don't think he's has a big enough tub to boil
out my tank. I'd prefer to find a place with a better setup for gas
tank repairs.
I have a few minor things to take care of before I can put the tank back
in but I suspect I'll have plenty of time for them while I'm waiting to
get it back from whatever shop I take it to. I'm also going to take
advantage of having easy access to the rear suspension area to do a few
odd jobs there too.
Roland
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