Barry,
This is dipping back into the dawn of my automotive experience, but I do
recall carrying out similar repairs in the past on British car fuel tank
floats as I worked in a garage in West London as I saved to go through
college.
I assume that you describing a problem with a brass (or at least metal)
float - if not, save time and hit the delete key now on this message. If
it is a metal float, you're overview is right on the money, but some of the
following anecdotes may help (hinder?) as you get to the end point.
The boiling off of the gas from the unit was done using hot oil in our
shop, but that may have been because it was easier to find a pan with thin
oil in it rather than one that we could fill with water. Either way, the
gasoline will vaporize easily at 100degC and emerge as a gas. I used to
watch the pan until a stream of bubbles emerged from leak, and then briefly
pull the unit out of the liquid and mark the spot with a permanent marker
(yea, it was a tang of an old file, but doesn't a marker sound good!), and
then put it back in oil and go and do some other jobs, occasionally
checking for bubbles.
Once the bubbles had stop appearing (and it took a long time - 60 or so
minutes I recall [but I was younger and on the clock ...], a heavy duty
soldering iron was prepared - we used a 100W Weller unit that you could
toast bread with - and the rosin cored solder to placed to hand.
The unit was then removed from the fluid, wiped off and cleaned up. The
leak point was then thoroughly scoured/cleaned using wirewool. Then the
unit was held over a small gas/propane flame to warm it thoroughly once
more (I seem to remember that more stuff would sometimes ouze out of the
leak at that point, but can't be sure) - I also remember that this step was
the one that worried me: a small metal container that had just contained
gas is now being warmed over an open flame (thank God I was 17 at the time
... and as we all know at that age, immortal).
Once the final warming was concluded, and the unit was allow to air cool
for 30 minutes or more (IMPORTANT - let it cool in air - don't dip it in
water since it will happily ingest the liquid all over again) the leak was
once more scoured/cleaned using wirewool. The leak was then soldered with
the soldering iron, without too much excess of solder if it can be helped
(since you're adding weight to the float). Given the changes in solder and
fluxes since that time, I would suggest getting some flux paste (plumbers
type) to apply to the leak area so you don't have to rely so heavily on the
flux-core of the more modern lead-free solders.
After it cooled, we cleaned it once more with wirewool, and then threw it
back in the hot oil to see if any more bubbles appeared, and if they did,
we avoided the foreman whilst we put the unit back in the customer's car on
the assumption that the discovery of the leak would take longer than our
departure to college ....
Hopefully, you will get much better advice from those more in touch with
their memories, but the above will at least confirm your initial thoughts.
Cheers
Tony Gordon
Midland, MI - 72 TR6
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Last night I swapped out the old Fuel tank with the new modified one for
the soon to be installed fuel injection (new return line fitting, 3/8 dia
lines etc). Upon taking the sender out, I noticed the float about a third
full of fuel. Luckily I had an old, non functioning unit out of the GT6
with a good float on it that I could use. It uses the same float, (or very
nearly identical) so I switched them. The only problem was that the little
rubber (damper o-ring) which encircles the float and prevents it from
banging the top and bottom of the tank was really too loose to use on the
new float. I didn't feel comfortable using it thinking that it may fall
off. It would just slide loosely on the new float so there may be a slight
difference in floats. I heard it banging the top of the tank this morning
:-). . .Anyway, Is there any way to remove the fuel from the old float? I
was thinking of boiling the float, hopefully causing the old fuel to
vaporize and thereby also showing me where the leak is and allowing me to
repair it. The only other way I could see to evacuate the old fuel out
would be to drill a small hole, drain, epoxy it closed, then find out where
the original leak is and then seal that up also. I would presume that the
leak would be at the weld seam but am not sure where as it looks to be fine
- unfortunately, you can't buy just the float. I may just make a brass one
and be done with it! It wouldn't be that hard -
Barry Schwartz (San Diego) bschwart@pacbell.net
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____________________________________________________________________________
Anthony Gordon Technology Education Coordinator
Saginaw Public Schools tel: 1-517-797-4855
ISDC, 1505 Ottawa Blvd fax: 1-571-797-4880
Saginaw, MI 48602, USA email: tgordon@saginaw-city.k12.mi.us
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