In an effort to share what I have learned, I would like to document how I
patched the gas tank in my TR4A. When I purchased the car, I was aware that it
had sat outside uncovered and the interior stripped out for almost 10 years.
The body was in generally good condition, with very little rust under the
circumstances. Even as I have disassembled the car, I found very few suprises
in the way of rust.
This past weekend I finally removed the gas tank, only to find leaves and
debris packed under it. This had held moisture against the indention for the
differential hump and allowed it to create a LARGE rust hole in this one spot,
approximately 1" wide and 6" long. As I live pretty far out in the country,
there are no welders or radiator shops close by - so I had to either come up
with another solution or lay out big bucks for a new tank. The following are
the steps I have taken and my observations. No financial interest, YMMV and
all that...
1. I removed all the paint from the outside of the tank with paint stripper
(the glue from the felt strips needed a second soaking). Looking back, I wish
I had also stripped the inside of the tank at this time, just so I had clean
bare metal both inside and out.
2. I treated the outside with POR's Metal Ready, per instructions. If I had
stripped the inside of the tank I cold have treated that at the same time.
3. I cut out a piece of the repair cloth to cover the hole and overlap onto
sound metal, trying to get it shaped so that it would match the contours of the
tank and lay flat.
4. Next I painted the first coat of POR-15 onto the tank. I used a foam brush
and made the coat thin as I could, but covering all bare metal. POR has great
self-leveling characteristic, so the brush strokes smooth right out as it dries
5. Then I placed the cloth patch into place, allowing the POR to act as an
adhesive to hold it in place as I smoothed it into position. If I ever had to
do this again, I think I would use some regular type cloth, such as an old
sheet or maybe blue jean material. POR's cloth takes a great deal of paint to
seal it, and the patch is noticable even after it is. With a thinner, more
tightly woven cloth it should be possible to get it to blend in and look stock.
6. I used the foam brush to dab POR-15 into the cloth, trying to fill the
gaps. Unfortunately, the foam tends to pick strands from the cloth, so you
have to be very gentle at this stage.
7. I waited the three hours suggested on the can to let the paint cure. At
this point, although I could still see through the cloth in places, it was
absolutely rigid and stuck to the metal tank. I put a second coat on both tank
and cloth and allowed it to dry.
8. After this point I only painted the cloth patch, waiting three hours
between coats (5!) until I could no longer find any holes in the tank by
shining a light from the other side.
9. After the last coat dried, I filled the tank with water to test if there
were any unseen holes left. After passing this test, I allowed the tank to dry
out, then treated the inside with Metal Ready, carefully avoiding getting any
on the patch (just being cautious)
10. After rinsing and allowing the tank to dry, I poured a small amount of
POR-15 inside the tank and sloshed it around to make sure the entire inside was
coated (a bit difficult with the baffles), draining the remainder back out.
After this coat had set, I used a can of POR Tank Sealer to coat the inside as
well.
11. As a final test, I poured a gallon of gasoline into the tank and let it
sit overnight to see if any leaks developed. At this time, I can report that
the tank holds fine, with no sign of leaking anywhere.
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