overheating problem

hey i need your help for a little overheating problem..i have a 89 grand prix with the 2.8L engine..the thing is that after about 15 min of driving my car..the temp gauge for the coolant comes on..i stopped the car and checked the level and the approximative temperature and it seemed fine..the fan doesn't start until the light is on for a couple of minutes..then the light will shut off..it's really weird i changed the coolant temp sensor, but i don't understand what's happening..even in very cold temperatures like (-25 Celsius) it will come on after about half an hour of driving..then gradually fade away then come back on and so on....the only thing that i can think of is maybe a stuck thermostat..or partially blocked..cuz the upper radiator hose gets hot as the engine is warm..so it's not completely stuck..any ideas..? thanks

it wouldn't hurt to go on ahead and install a new thermostat since it's not expensive and easy to do. the radiator could have a partial blockage too...you might want to flush it out.

Change your thermostat, its the easiest fix. If that doesn't work check for suction pressure in your hoses, make sure when you rev your engine that the hoses aren't compressing. If they are then you are either low on coolant or you have a block in your hoses or radiator.

more then likely its the thermostat though... cuz i had a problem like that b4..

i just got my thermostat fixed today, but my problem was the opposite, it ran too cool.

The reason it was running cool and not hot is because your was stuck open, but it sounds like his is having troubles opening.

yep i guess it takes a too long time to open..what seems odd is that if the ECM senses that the coolant is too hot why isn't the fan triggered?anyone knows where i could find one of those 160 degrees thermostat?also i never flushed the radioator, but the coolant seems new..(no rust signes or of corrosion) i got the car almost 2 years ago...and the problem arrived just like that one day...

also when changing the thermostat, on those 2.8 L engines...is thee any coolant loss? thx

Yeah there will be some coolant lose, so you might want to buy some just to top it off, you could probably buy a 160 degree stat at like autozone or kragen or any parts stores around you, if not go to club gp and post a question on there they should be able to help you.