At 05:54 PM 7/5/2001, Mark Dorm wrote:
>Pressure cap? What exactly is this and where is it? The other day I parked
>my vanagon, and sat for a minute to think about something when suddenly
>there was this hissing noise like air or steam was coming out of a tire or
>the coolant system. I jumped out of the vanagon, put my ear near both front

It's the blue (or black) cap of the expansion tank.  It is arranged to open
at around 14 psi and let coolant flow into the recovery (fill) tank.  It
also opens with a slight vacuum to allow coolant to be pulled back from the
recovery tank into the pressure loop.  In most cars you'd call it the
radiator cap...

david

David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"