[s-cars] Overheating!

[CyberPoet]

One of two or three things has happened:

(A) The water in the hoses to or from the radiator froze solid and
wasn't letting any/adequate water pass. Can be a problem in places
where the ambient temp is 7 degree Fahrenheit.

(B) The water pump failed (possibly ejecting a fin in the process into
the radiator hose, but more likely just gave up the ghost). If the
engine got cold enough that the water froze at the pump, this can
readily happen. Check your belt to see if there is sign of heavy wear
suddenly, and check the water pump pulley for movement while someone
else starts the car.

(C) The thermostat valve has gone and bit the dust, wasn't opening as
far as it should have (or at all). Most likely culprit, IMHO.

To answer your other question, yes, all VAG vehicles from early 80's
(and possibly before that) have a pressure relief valve in the coolant
reservoir/overflow container cap. Nastiest of nasties -- I've had that
stupid little relief valve fail without noticing (it took a while to
figure out why our old Golf was springing a pin-hole leak through
in-dash heater cores every 4 to 7 months, which take a *$% amount of
work to exchange). If your coolant reservoir cap is over 8 years old,
I'd suggest replacing it as a preventative measure.

If the water pump pulley spins up OK when someone is cranking the car,
and there is no signs of excess wear on the belt (nor heavy
skuffing/skid marks on the water pump pulley), plan on replacing the
thermostat ASAP. Remember to test the brand new one for both cold and
hot operation before installing it (bowl of ice-water, pot of
near-boiling water).

Best Wishes,
=-= Marc Glasgow



Matt wrote:
So i pop the hood: plenty of coolant, aux fan running.  It's 7 degrees
here
today, so kicking on the compressor manually isn't happening.  I crank
the
heat, and continue home as it's <10 miles on back roads with a steady 55
limit.

Make it home, temp gauge is still elevated, autocheck has gone off, then
clicked on again.  Oil temp is still normal.  Pop the hood and continue
to
run the motor so as to (hopefully) not permanently damage the engine.
still
plenty of coolant though some has now sprayed along the hoodliner near
the
reservoir.  an area near the steering rack is also sprayed, yet there
is no
sign of a leak anywhere.  Aux fan NOT running.  WTF?  is there a
pressure
relief of some sort on the coolant reservoir?

so i shut the car off after another minute or so with no change.  Go
back
under hood, radiator is ice cold and there's very little pressure to
escape
from the reservoir.  And, a strange clicking noise that I can feel via a
coolant hose that is closer to the firewall, near and above the
bellhousing
of the transmission.  it's behind the afterrun pump, closer to the
firewall,
if that makes any sense.

So: new h20 pump, T-stat, and coolant change last year.  Any thoughts?
I'm
about to check Bentley, but need to ask the collective wisdom here.
Something must have given up the ghost.