99 Grand Am, Overheating after engine change

[Chipmunk222]

99 Grand Am, 6cyl, replaced engine with a new rebuilt.

Engine fans are coming on intermittantly, but the car will overheat intermittantly also. Sat for 30 minutes running in the yard and temperature
ran about 200 degrees, fans were on, car runs fine... drove the car down the road a half a mile one time, the oil light came on for a second and went off .... no overheating. Drove the car another half a mile and the fans wouldn't kick back on and it started overheating again.

I have burped this system several times but seems to do nothing.

Anyone have any suggestions?

Thanks

[wbain]

It is possible that you need to replace the heater core. I had the same thing happen and ultimately the engine went. I did replace the engine and was told that was my original problem - by the people who replaced the engine. Matter-of-fact, they would not put in the engine without replacing the core.

[Chipmunk222]

I think we may have found the problem, and you are right, it may have been the heater core, we weren't getting any circulation of the coolant so we did a radiator flush and just for fun blew on the hose to see if anything was able to pass through the system and something around the heater core area sounded like it released something.... after putting regular coolant back in the car it runs great and seems to have solved the problem.

[xeroinfinity]

yeah air trapped in the cooling system will do the same thing.

and Welcome to AF !!