Pontiac Repair: 2002 Pontiac Montana overheating, coolant level, pontiac montana

Question
I have changed the thermostat and it still overheats.  I also replaced the water
pump.  When it runs it has little or no pressure in the upper rad hose and as the
engine heats up the hose is cold as if the thermostat is not opening.  When I
shut off the engine, the thermostat seems to open and the upper rad hose gets
super hot.

Answer
Hi Alan:

well it could be a few things. you couls have had a bad thermostat to start with or it was low on coolant. I doubt the new one is bad as well. That van is hard to purge the air out of the system. There is an air bleed on the heater pipe that runs along the front valave cover it's just above the water pump. fill the system up with that open. and run it with it just opened a crack. run the idle up and down wile kkeping an eye on the coolant level and the tamp at the same time DO NOT OVER HEAT IT. once all the air is purged out it should be okay. If not then I would suspect that you have other issues like possably a bad head gasket??? It's hard to say If the engine has over heated more than once that's a good possability. Good luck :)