expansion tank cap

[Fisher, Scott]

Phil Payne once told the list that the caps were designed by Audi to be
replaced after any loss of pressure.  (Odd -- I can't find it in the
archives.  Found one of MY old postings about the first time I went through
the CGT's cooling system right after I bought it...)

That's been my experience -- when I (well, the '83 CGT) lost a heater hose
two years ago and blew coolant all over the engine bay, the car didn't
pressurize properly even after replacing all the hoses.  I was afraid of a
head gasket leak, of course, but I replaced the cap and it's been fine ever
since.  Because "ever since" includes several runs from roughly sea level to
3900 feet at 75-80 mph in 100-degree weather with the air conditioning on,
I'd support Phil's answer as being correct.

--Scott Fisher
  Tualatin, Oregon