Either it is leaking somewhere or the coolant is getting forced out while
driving. Get a coolant system pressure tester, one with a guage. Pressurize
the cooling system and see that it holds. That will tell you whether you
have a leak or not. Likely unseen leaks include the heater cores and of
course internal engine leaks. If the is no leakage then you need to consider
combustion gasses still getting into the cooling system and at some point
lifting the relief in the pressure cap and blowing some coolant out. This
will usually happen only while under load, not just when idling.

For the low gauge reading you need to determine if it is the gauge or a bad
thermostat.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Craig Cowan
Sent: Friday, February 24, 2012 12:02 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Coolant vanishing

My new bus,  a 90 automatic which sat for a few years seems to be makin
coolant vanish. I checked it for leaks thoroughly before its commissioning
and we addressed some problems.  Now I find myself filing the expansion
bottle behind the license plate for the second time. The system holds
pressure, I don't know of any leaks, the heads have a thousand miles on
them, and the heaters produce heat. The temp gauge has always seemed to stay
a little low but that may just be where this one likes to hang out.

Any suggestions on where to start? I've been out of the wbxer game for a
little while and my head still thinks engines are supposed to have simple
and reliable cooling systems like my zetec.

-craig
'85,'90,'87 Syncro