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