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In message <199810142249.PAA29070@mailman.cisco.com> "Henderson L. K. Nuuhiwa" writes:

> Wanted to check with the collective mindset on this.  Anyone heard of
> running out of coolant in the course of an hour and a half?

Took that long, huh?  I've seen it done in 200 metres.

Most obvious cause is a hose split.   Most Audis are designed to run at
around 1.4 bar pressure in the coolant system - stops it boiling at
the kind of temperatures you find in the cylinder head water galleries.

Get a hose split, and there's a combined effect.  Leakage prevents
pressure maintenance, and that in its turn allows boiling off.

Any reasonably equipped shop should have a coolant pressuriser.  The
system is filled back up, the pressuriser is screwed on in place of the
header tank cap, and the pressure is pumped up to 1.4 bar.  Audis have
48 x 3mm threads - most kits will deal with this.   Most common split
is at the cylinder head end of the top water hose.

Head gasket failure can also cause coolant loss, but IME it is a more
gradual process - developing over months before the final breakdown.

One not to forget - get the cap tested as well.  It contains safety
pressure relief valves that sometimes fail.

 Phil Payne
 Phone: 0385 302803   Fax: 01536 723021
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