1998 Pontiac Sunfire Not Heating And Then Heating Tomuch?

[jafo169]

I Have A 1998 Pontiac Sunfire. It Wouldn't Heat Up So I Changed The Thermostat. And Then It Would Heat Up When It Was Sitting As Soon As I Would Take It Down The Road It Would Cool Down And Bowl Cold Air. And I Put Cardboard In Front Of The Radiator And Made Sure The Fan Couldn't Come On. But It Still Didn't Help. So I Changed The Thermostat Again Then It Started To Overheat (and Yes I Bleed It Every Time I Change It) Anyway So I Changed It Again And Now It Heats Up To The Right Spot When It Is Sitting And When I Go Down The Road It Heats Up To Right At The Over Heating Mark.if I Drive 45 Miles A Hour Or Less It Is Fine But If I Go 55 Miles Or Over It Heats Up To The Hot Mark.and I Took The Cardboard Out And Hooked The Fan Back Up . So What Do You Think It Might Be..thanks
Sorry The Head Was Checked And Good.radiator Is Fine
I For Got To Tell You But The Fan Wont Turn Of Either Unless I Pull The Fuse

 

[not_delivery]

could be your radiator, blown head gasket, or a crack in the head.
i would take it to a local honest mechanic, and have it looked at

 

[sevenpetals26]

try this...

I have a 97 sunfire and I have had the same problems I did the thermostat, water pump, fan hooked up by fuse still... come to find out with all this reading is that when an oil pump starts to go bad the engine overheats... Im having other issues that lead me to that. In the winters Id run freezing after all the changes overheating... Mybe u shuld check the oil pump...