In a message dated 96-05-20 23:13:10 EDT, Gcarlen writes:

<< 
I'll definately take your advice on the thermostat.  Certainly makes sense.
 The engine temp seems to be fine in the evening and at night when the
outside temperature is cooler.  Hmmmm....I don't know.  Would the stretched
water pump belt contribute to the problem?  Any ideas about the heat coming
through the cab vents when they're closed?

-Gregg >>

Is the radiator fan working properly?  If outside temp affects running temp,
radiator could be suspect.  Warm air coming through vents sign of water valve
not closing completely. Air flaps never seal that well.  Water pump belt
tension will not effect cooling capacity much.  Will effect alternator
charging as belt slipps.  Belt will burn up.

Hope this helps,
Dennis.