I think you have a clogged radiator.  
Been there, done that.  

Take the rad to a shop and have it flow tested and "rodded out".  
Beware - depending on the type of corrosion and gook in the rad, the rodding
out process may be only a temporary fix.  Expect to pay $50 for the process
if you carry in the rad, $100 or more if they take it out.

good luck - Frank

BTW - new rad is $400+  (which is what I ended up doing :-(  )

 >Date: Thu, 18 Jul 1996 16:47:26 -0500
 >From: Paul Uusitalo <puusital@mv.us.adobe.com>
 >To: Multiple recipients of list <vanagon@lenti.med.umn.edu>
 >Subject: Greetings Again & Overheat Help
 >
 >Hello All:
 >
 >As a desperate measure to preserve my sanity (and to keep some portion of
 >the day for doing my actual job), I dropped off the list about 6 months
 >ago. But news of the water/air split was enough to get me to resubscribe
 >and see if I can bear the traffic, so here I am.
 >
 >And wouldn't you know it, I've got a problem.
 >
 >Over the past month or so, my '87 (Syncro Westy) with 69k miles has begun
 >running hot. Historically, the temp. gauge would sit right at the center
 >(over the warning light) when the engine was at operating temp., and the
 >cooling fan would only kick on in warm weather traffic. Now, in cool
 >weather it's running 2/3 towards the top of the gauge, and the fan is
 >coming on any time I'm not at highway speed.
 >
 >I took it into the shop where we've done the following:
 >
 >new thermostat & bleed system	- No change
 >system pressure test 		- OK
 >2 different tests for CO2 in coolant	- Negative
 >thermal probe test of coolant temp	- roughly normal at engine outflow,
 >radiator, engine intake.
 >exam all hoses, etc.			- OK
 >
 >Other info:
 >
 >no abnormal water pump noises
 >no coolant backup into overflow tank
 >coolant has been changed frequently over the life of the bus
 >turning on heater significantly reduces engine temp (almost back to normal)
 >no external signs of head gasket leaks
 >fan temp switch and temp gauge both concur that the engine is hot
 >(functioning seems correct)
 >rear passenger heater air does not seem very hot, even when engine is
 >definitely hot
 >
 >Any guesses as to what's going on here?
 >
 >Thanks!
 >
 >Paul
 >puusital@adobe.com
 >
 >

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Frank Terhaar-Yonkers,  Manager
High Performance Computing and Communications Research
MCNC
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