second problem

[douglasd]

2000 runs fine then overheats, then runs fine.........can the thermostat be bypassed to check it.......top hose is hot, bottom is cold.........heater core supply is hot, return is cold.....thanks

 

[Disco Mike]

How many miles on the truck, where is the bleed screw located on your truck, on the upper hose or on the black plastic tee?
Do not continue to drive the truck or you'll toast your engine. No the t/stat can't be by-passed. Have you, or do you know how to bleed the coolant system, here again, if not quit driving it or you'll loose the engine.

 

[joey]

My bet is your T-Stat is already in bypass mode and that may be your issue, but as Mike is about to point out you may have an air pocket in the system as well.