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Gas tanks revisited

To: british-cars@autox.team.net
Subject: Gas tanks revisited
From: phile@pwcs.stpaul.gov (Philip J Ethier)
Date: Mon, 30 Aug 1993 13:20:59 -0500 (CDT)
Remembering Roland's fun time with the Cobra, I was really looking forward
to getting at my Europa gas tanks.  

I figured I should get to them before lifting the body back on because it
is difficult to raise the car high enough to fit them in without a hoist. 
The way I got them out was to disconnect them and lower them to the floor
under the car.  When the body was lifted, the tanks were snatched out of
the way.  Then the chassis was rolled back away from the body and a wooden
cart brought in from the side to support it.  The tanks are taller than
wide, and the bottom is larger than the top.  They don't have the little
swimming-pool for trapped water on the top for which Europa Twin Cam tanks
are infamous.

I suspected that the tanks were not 100% petrol-tight.  I also figured
there must be some rust and other unmentionables in there.  I investigated
having them boiled by my radiator place.  No dice.  Insurance won't let
him do gas tanks.  

I called the local gas-tank specialists, Tank Re-Nu in Eden Prairie, MN. 
They told me they would clean and line my tanks for about $130 each.  This
is not in the program, so I went looking for home kits.

Eastwood supplies the stuff, but they are not the cheapest place to get stuff.

I perused the catalog of good old J C Whitless.  About $25 brought me a
kit containing Part A, a phosphoric acid concentrate, Part B, a small
bottle of MEK (methyl ethyl keytone, a serious solvent) and a quart can of
white tank-slosher goo using MEK as its volatile component.  Turns out to
be "Kreem" brand.

Friday August 20 promised to be a bit drier than the incredibly humid
weather we have had, so I vacationed out of work at 11:00 AM and hopped a
bus for the homestead.  

I had poured the last of the gasoline out of the tanks some time back
(burned it up in the lawn mower) so they were dry.  The right tank has no
gauge, just a short tube in the middle of the front.  This was for the
return from the evaporation control system.  Why it is in the middle of
the tank, I have no idea.  In the left tank, the gauge sender is in this
location.  There is a bayonet ring about 2-1/2 inches in diameter holding
the mounting plate against a rubber seal.  Easy to remove.  

The gauge parts all seemed nice and clean, some kind of gold-tone finish
on them.  There was rust only on the outside of the mounting plate.  The
return pipe on on the left tank is right in the mounting plate, so I did
not have to worry about getting slosher in it.  The box seems electrically
OK.  I metered smooth resistance changes when moving the arm.  The float
is a sealed translucent plastic barrel shape.  It seems to be about 1/10
filled with gasoline.  I can't see how it got in there, as there appear to
be no leaks.  I can only assume it permeated the plastic.  I figure if it
takes another 23 years to become 2/10 full, I can live with that.

The tanks had some rust flakes, solder splatters and unidentifiable chunks
flying around loose.  I shook them out and in some cases got them near the
filler neck and fished them out with my foot-long tweezers (very handy LBC
tool).  The left hand tank is the one that came standard with the car.  It
is easier to view than the optional right tank.  You can shine a light
into the filler neck and look into the gauge port or vice versa.  The
right tank is a bit more problematic, as your head tends to block the
light when you attempt to look in the filler neck.  In general, they did
not look too bad.  There was some light surface rust on the inside walls. 
The worst rust appeared to be on the pickup tube in each tank.  This
enters smack in the center of the inboard side of the tank, bends and
follows the side down to another bend at the bottom, then runs right on
the bottom to an abrupt end right in the center of the tank bottom.  A
rust-through on this tube would prevent your fuel pump from getting all
the gas out.

I flushed the tanks well with the garden hose.  Short pieces of rubber
hose with the ends kinked over served to cap the lines.  The gauge port
was closed by a circle of  closed-cell foam rubber held in by the bayonet
ring.  Next step was sloshing each tank with two gallons of hot water and
automatic dishwasher detergent, then filling them with water, dumping and
more rinsing.  Then it was time for the de-rust and etch process.  I put
just over a gallon of very hot water and half of acid solution "A" into
each tank.  The instructions say to put the acid in first, then chase it
with the hot water.  That's not what they taught me in high-school
chemistry!  The fillers were covered with race tape and the the tanks were
left to sit, occasionally to be rotated to a new position.  The acid went
in at 2:30 PM Friday.  There was a dinner meeting of LOON (Lotus Owners Of
the North) at the Lotus Restaurant that evening.  Terry Pitts came back to
my place afterwards, and we rotated the tanks and bench-raced for a bit.

Saturday I continued the acid rotation amidst other jobs.  About 2 o'clock
the acid was dumped into a sturdy plastic jug and marked for future use. 
The big water flush began.  As I had done on the other flush stages, I
made sure to uncap the lines and gauge port sometimes for a good flush. 
The inside looked dull grey, so I assumed that they had been etched.

Then I took one tank and shook it out as well as possible (the other tank
waited, full of water).  After I had shaken out all the water I could, I
poured half the MEK from the "Part B" bottle into the tank.  I shook it
round to absorb the excess water and prime the surface.  The instructions
say you can do this and not have to get the tank perfectly dry.  I forgot
that MEK would take the adhesive off the exposed race tape, though.  Might
be better to have one piece of it over the filler neck adhesive-out.  The
slight MEK leakage showed me that the small hole in the left tank.  I did
not want to stop the process to repair the hole, so I put a piece of race
tape on the outside.

Then I poured half the can of sealer into the tank.  You are supposed to
slosh it slowly everywhere, then let it sit on one side for several
minutes, then slosh again, let it rest on a different side, slosh again. 
During this time I would blow through the pickup tube now and again to
make sure it was not plugged with sealant.  Don't inhale, that MEK is bad
stuff.  I did this outside in a slight breeze.

You are basically supposed to do this until you get sick of it.  So I had
time to start up the other one during the waiting periods.  Then I had
both of them going. When I got sick of it (had to clean up for a family
gathering), I poured the stuff back into the can.  I had used up about
half of the stuff for the two tanks.  The tanks were left to dry sitting
on their sides, so that the pickup tubes would not plug.  I wished that I
had the facilities of the 3M research lab.  I would have set them up in
the fume hood with slow stream of dry nitrogen piped through them.  But
this is the real world, so I had to settle for putting them in the garage
with fans blowing at the filler necks.  This was more efficient for the
left tank, as I had taken the seal out of the gauge port.  The fan was
pointed at the filler, so some air was coming out of the port. I left them
this way for almost a week.  They dried with some runs, but I think they
will be OK.  I will put a separate filter on each when they are in use.  

Next comes the body lift.  The prep continued the next weekend.  See
"Lotus Lift"


Phil Ethier, THE RIGHT LINE, 672 Orleans Street, Saint Paul, MN    55107-2676
h (612) 224-3105  w (612) 298-5324    phile@stpaul.gov                    USA
"What could go wrong?" - Big Bird


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