Air or exhaust gases in the cooling system can give the same symptoms. Try
bleeding the cooling system first. Of course if that fixes the problem, you
have to find the leak, internal or external. Also make sure the pressure cap
is good. If it can't hold pressure in the cooling system, the coolant will
eventually work it's way out while driving and allow air to enter. Another
possibility, if the coolant isn't strong enough, and it's cold enough, the
radiator may be filled with slush, keeping the water from flowing.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf
Of John McLean
Sent: Sunday, January 21, 2001 6:49 PM
To: vanagon@GERRY.VANAGON.COM
Subject: overheating

Seeking wisdom...

All of a sudden yesterday my engine started overheating.   Today I went
out to see if I could figure the problem out.  My observations show me
that there are independant coolant lines that go to the front and rear
heater cores.   Also, the large coolant line coming out of the back of
the thermostat housing goes to the main radiator.

I am getting heat out of both heaters but even as the coolant
temperature climbs the main radiator is still cool to the touch and the
fan is not blowing.   When I place my hand on the main (large) coolant
line behind the thermostat housing ( and crawl under the bus to feel the
main (hard) lines to and from the radiator ) it is cool.  At the same
time the small (flexible) lines to the front heater are hot.

So...  my investigation shows me that 1) the heater cores both get
coolant independant of the thermostat and 2) my thermostat is stuck and
I am getting no flow to the radiator

Am I correct in my thinking?

John McLean   87  Vanagon  GL