I had this same puking coolant problem at one time
that was on-again, off-again for a couple years,
actually.  Unfortunately, i can't give you a
definitive answer, because i apparently just felt like
building an engine, anyway.  But, i'll give you a
theory of mine (after some tests i ran).

I fabricated a little pressure tester out of an old
gutted blue cap, a bicycle pump, and the stuff needed
to hook those up.  One night, i pumped it up to about
16psi (about all the pressure cap is supposed to hold,
right?), and let it sit for about 12 hours.  No
change... maybe 1psi.  After that, i let it idle until
it got up to temp (radiator fan cycling).  Again, no
change in pressure.  So, no leak and no exhaust
gasses?

So, what do i kind of think it was?  A bum cloth
braided hose.  Cracked enough to let air in (maybe on
cool down? maybe at some random low-pressure event?),
but not cracked enough to let water out.  That whole
viscosity thing, you know.

Again, i don't know for sure, but that is all i could
come up with given the symptoms (exactly what was
described here!).  Oh yeah, i also had my water pump
replaced with no change in an effort to fix the
problem (pissed me off, too, because i left the van at
a reputable mechanic's for three weeks and,
essentially, an open pocket book saying "i just want
it fixed when i get back... do *whatever* it takes!
Not something i usually do.)

Anyway... check for brittle hoses.

-Damon

--- mark drillock <drillock@EARTHLINK.NET> wrote:
> Here is a suggestion. Put a pressure gauge on the
> cooling system and
> verify that the pressure is still going up very fast
> when the engine is
> running at idle after full warmup. If it is, shut
> off the engine and
> relieve the pressure. Then remove one sparkplug
> wire, ground it, and
> start the engine. If the pressure builds again, shut
> down, relieve the
> pressure and move to another plug wire. When you get
> the one with the
> leak the pressure should not build or should build
> much slower.
>
> Mark

=====
'84 Westy (Sparky) w/2.3L WBX (wow... it actually works!)

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