Saturday morning I poured the etching solution in the snake's gas tank
into a bucket to see if it looked as dirty outside the tank as it did
inside. It did. It had turned nearly opaque and was about the same
color as used mop water. Also quite a bit of flakey crud came out with
the solution. Some of this crud was no doubt chucks of rust loosened by
the phosphoric acid, but I think much of it was partially dissolved
solder from the tank seams. Since there was so much residue in the
bucket, I decided to flush the tank with water until what came out
looked relatively clean; which I did. Next I poured in another gallon
of metal etch. Normally this solution is diluted about 3 to 1 but there
wasn't any noticeable rust in the tank so I filled the tank to the top
so that all surfaces would be covered. I left this concoction in for
several hours, then poured it out. Now I got really serious about
flushing. I spent at least half hour pouring in water, slushing it
around vigorously and then pouring it out. The loose crud was difficult
to remove because there weren't any convenient low spots for it to
settle into where it could easily be be rinsed out later. The only
method of removal was to get as much of it suspended in the water as
possible then pouring the water out. Eventually the water cleared to
the point where further effort seemed pointless; each new rinse only
produced 2 or 3 small specks at the bottom of the white plastic bucket I
was pouring the rinse into. This was tedious work and my arms were sore
the next day and a bit bruised as well. Having a couple of neighborhood
kids "helping" didn't make things easier either. No amount insisting
that I didn't need someone to empty the bucket or squirt water into the
tank deterred them. Even my curt responses to the their kibitzing
grandfather's attempts at conversation didn't get the message across.
By the time I was finished, everything in sight was soaked, including
me.
Now it was time for the next stage: getting the water out. I started
with two alcohol rinses. Next I poured in the half pint bottle of MEK
that came with the tank sealer kit. This didn't seem adequate to me for
an 18 gallon tank so I pour in what was left in a quart can of MEK I had
stashed in the garage. This was followed by another rinse with a quart
or so of acetone. Satisfied, I let the tank air dry for half to three
quarters of an hour. By then the tank was bone dry inside.
The next step was to pour in the sealer; I poured in the pint that came
with the kit plus an additional pint. I slushed this around according
to the directions, letting the tank rest on each sides for 10 minutes or
so, saving the top for last because that's where the filler neck was.
While it was on its top side the excess sealer ran out the filler hole.
I could have blocked this opening but opted not to because I didn't want
a glob of sealer partially blocking the filler tube. Besides, the
instructions suggested draining off the excess for later use.
Since the odor of the curing sealer was so strong (MEK, I think), this
operation was mostly performed outside. Finally I rotated the tank so
that it was upright and left it until the next day. This had all taken
far longer than I thought it would, but I was still on track to get the
tank installed Sunday. Meanwhile I could take care of some unrelated
chores planned for the day and get re-hydrated (internally) with some
Anchor Steam.
Sunday morning I peeked into the filler neck to check on the sealer's
curing progress. Off to one side at the bottom was what appeared to be
a largish flake of rust! The bright sunlight made it hard to see in the
dark tank interior, so I moved it inside the garage where I could shine
a strong light inside without being overwhelmed by the outside light.
The flake turned out to be a rust colored moth that had found its way
into the tank. I could see a powdery red trail where it had floundered
around before getting permanently stuck in the sealer. I poked a long
wooden dowel into the tank to see if I could get what was left of the
moth out. To my surprise, the sealer was still quite gooey. The sealer
directions stated that at least 24 hours drying time should be allowed
so I figured it would be pretty well along after 16 hours. Hmmm, this
was going to alter my plans a bit. A few more hours probably wasn't
going to be enough time. I wouldn't be installing the tank that day
after all. In that case, I decided I might as well use up the 1/2 pint
of excess sealer I had drained out the previous day, so I move
operations outdoors again and pour in the sealer. This time I
concentrated on the sides of the tank since the bottom already had a
fairly thick coat. After completing all of the rotations, I sat the
tank on one side and put a small fan in front of the filler neck to keep
a continuous flow of fresh air going in. The instructions suggested
this as a way of speeding up the curing time. I left this setup for
several hours while I took care of a few other tasks.
One of the other tasks was to replace some threaded aluminum inserts
that screws securing a panel in front of the the gas tank at the rear of
the cockpit screwed into. These were of the same size and type as the
ones used for the Lift-The-Dot studs. Being made of chrome plated brass
and exposed to the elements, every screw had corroded solidly in its
insert. I manage to unscrew a couple, but had to yanked out the rest in
one piece. None of the inserts were in usable condition when I got the
panel off. I installed new aluminum inserts backed with large stainless
steel washer and replaced the brass screws with stainless screws. I'm
not too happy with this arrangement but the inserts only have a thin
aluminum panel (much thinner than the body skin the L-T-D inserts are
in) for support and there's no access from the rear. It's a very Mickey
Mouse arrangement.
By late afternoon the sealer had hardened enough to remove the
compression stopper I had place in the the fuel outlet opening. In
spite of the stopper, some sealer had gotten into the upper threads.
Fortunately it wasn't too hard to scrape this stuff out. I could have
put the tank in the car at this point since everything was ready to go,
but I decided to let the sealer cure for a few more days outside with
everything open. I didn't want this smelly stuff outgassing for the
rest of the week in my garage. Next weekend for sure!!
Roland
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