so blew a head gasket..... took the plenium off and valve cover off adn drained coolent...... let it sit for 5 months. rebuilt the motor and now it runs fine but it over heats. the wierd thing is it will be fine for a bit then the heater will blow cold air and then the car will get hot.... heater starts blowing hot air the car cool down. have already changed thermostat

 

Does the fan kick on when your idleing? Did you check to see if the heater core coolant lines are both warm?

 

has a mechcanical fan and it will work just fine go cold and get hot again.... and when it goes cold the car withh get close to over heating

 

is the fan working right?

did you put on the head gaskets correctly?

 

Air in the system.

 

the gasket is put on correct and i hvae bleed it numerous times..... im thinking water pump

 

The only way a water pump will cause the issues youve stated is if the impeller has come free from the shaft, which in itself is super rare, or the blades of the impeller have corroded/worn off, of which ive seen twice, after about 2000 water pump changes.

 

quickly fluctuating engine temp/heater temp is almost solely associated with air pockets trapped in the system.