Sounds like a bad pressure cap. If all is well, the main pressure tank
will always be full after a few heat cool cycles.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of James Benthall
Sent: Wednesday, June 29, 2005 8:43 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Help... Engine troubles, rapid backfiring under load.

Ok Ken, I have to ask this one.  Do you still continue to fill the
expansion
tank (one behind
the license plate) even after the coolant reservoir is full?  From  when
I
first got mine it has
always ran with the reservoir full, and any coolant you put in the
expansion
tank always either
drips on the ground, runs to the reservoir filling it all the way to the
top, or dissapears?  I.E.
my expansion tank is always empty.  I have never bled my system, so
could
this be a factor?
Btw, my van is not running hot.  Thanks for any advice.
James in Houston
87 Westy