Pontiac Repair: cooling system problem, head gasket, backflushing

Question
1994 grand am se 2.3 quad 4, I had to many problem, change head gasket, thermostate last year, then heater core exploded, I bypassed it by a piece of pipe, then everything was running fine on the right usual temperature (180) , now I changed the heater core, cleaned the system with system cleaner from Autozone, backflushed the system, put everything together, result, car overheating to (220)and stay there, what happened, I suspect 1-thermostate got cloged after backflushing, 2- the hoses go to heater core has bypass maybe cloged 3-heater core from autozone not good quality doesn't let enough flow, what do u think, thanks

Answer
Hi David:

I agree with the possable thermostat issue more than the heater core but you never know. Also those engines are realy hard to purge the air out of once you drain the coolant down in them. It may just be an air pocket in the system as well. As a good rule of thumb after any kind of a chemical flush in a cooling system it's a good idea to change the thermostat. Good luck :)