Ok, here are my theories on the subject (living
through the same thing, myself... although it has been
intermittant for about 5 years(?!))

-Pressure on cold system:  Gasses get into coolant,
and even though they cool, they still maintain
something close to the 16psi the cap holds before
opening and dumping coolant into refill tank.
-Never drains back into expansion tank: gasses in
lines keep positive pressure, therefore cap doesn't
open the other way at vacuum.
-Air bubbles: lotsa hoses and a van that drinks a
gallon of coolant a day! I thought about driving with
my radiator bleed screw open when i still had about
500 miles ahead of me with this problem.
-Where does coolant go: Out the tailpipe.  Pistons
create both positive and negative pressure, steadily
exchanging fluid for exhaust.  Take a nip of the
good/blue stuff (what is that, a mai tai?), and then
drunkenly blow a few bubbles back into the glass.

Something with your seals on top of the piston chamber
is all wonky.  At least that is a theory.

We should have a consortium that pairs up all the
people with bad 02 sensors, gumming up their plugs,
with all the leaky coolant guys like us so we can
steam clean the oil guys' plugs, and then they can
pick us up when we toast the motor...

I'll stop it at that, as i've gone on for far too long
about something i know little about.

-Damon

--- zampano <matthias.k@ATTBI.COM> wrote:
> I would also wonder why there's pressure on a cold
> coolant system, and
> why my expansion tank fills up, but never drains
> back into the coolant
> tank. Also, why do I still get bubbles after
> bleeding it for 15 min???
> I did this for three days in a row, and have been
> doing it steadily
> over the past 3 months. To the tune of almost every
> week/ 350miles.
> Where does the 1 gallon of coolant go every week,
> and now every day.

=====
'84 Westy (Sparky)
'65 Kharma Ghia (Dharma)

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