Wierd coolant temp behavior

[Michael Williams <urquattro@surfree.com>]

hey all, i have a question... i have an MC in my UrQ, which im sure most 
of you know, and i have a seperate VDO temp guage for the coolant.  The 
fan doesnt come on automatically, so i have to turn on the "air 
conditioning" to get it to run.  By that i mean that there is no air 
conditioning, but pushing the temp control all the way to cold manually 
turns on the fan.  I do that if i sit idling or if the coolant seems to 
be getting hot.

the question i have is that the guage, on the freeway, no fan on only 
reads whati  believe is 150 degrees F.  It has boiled over before, and i 
also got a brand new radiator cap.  The confusing part is that it boiled 
over at just about 200-210 degrees when i let it idle one time without 
turning on the fan...  I would imagine that it shouldnt really be boiling 
over at this temp...shouldnt the pressure in the system be low enough to 
not cause the cap to release pressure, but high enough to inhibit the 
boiling itself?  if so, what could be causing too much pressure in the 
coolant system?  

thanks all...

later...

Michael Sheridan Williams
San Francisco, CA
ICQ# 11740998
1983 UrQuattro, MC--1.8 BAR, borla, 16x7.5 OZ Mito's w/ SP8000's, K&N
1985 4000S Quattro, Koni Yellows/Coilover (2B), strut brace, Sport 8000 
Tires, K&N
http://members.aol.com/daserde2