Thread: cant figure it out

hopefully someone can help me? i've got a overheating problem with my 2002 grand prix, i've tried everything, but still no fix. first i found that the previous owner had just put water in the radiator and i thought that was the reason why. but i replaced the coolant and the radiator and still overheats, replaced the thermostat and that seemed to fix it for about a week or two. then it started again, but this time my temp guage would just go up and down, up and down. and when the temp would get really hot my heater would stop working, then when the temp dropped my heater would start working again. that part still confuse's me, so i figured it might be the coolant temp sensor. i replaced that, and now the gauge goes straight past 260 and stays there. and now it wont stop overheating. please help, i cant figure it out.

First off coolant is the best cooling substance available on this earth to date. All anti-freeze does is raise the boiling point and prevent the water from freezing. But straight water will cool better than any anti-freez mix any day.


First question. Are your fans comming on? If they are not on when your car is overheating then run in and turn the A/C on full blast. Max AC. Now check and see if they are on.


Let us know the outcome.

Originally Posted by 99prixgt

just throwing an idea here, possibly blocked coolant passages?

Definetly a possibility. Also may be a faulty thermostat.

is there a problem with the coolant temp sender? as to say is it really over heating? as for the fans, does it keep a decent temp when you're cruising and mainly overheat when you're city driving? that would lead me to the fans. thermostat, pull it and heat up some water. they have thermostats now that default in the open position so that they don't have that weak point anymore.

Originally Posted by osirus

is there a problem with the coolant temp sender? as to say is it really over heating? as for the fans, does it keep a decent temp when you're cruising and mainly overheat when you're city driving? that would lead me to the fans. thermostat, pull it and heat up some water. they have thermostats now that default in the open position so that they don't have that weak point anymore.

And just to add if it is the Temp sender the fans will run all of the time.

was just throwing out some things that i'd check first.

Originally Posted by osirus

was just throwing out some things that i'd check first.

Sorry I actually did not mean to quote you. But was just adding that bit of info.

There you go

Originally Posted by osirus

I don't know how I ended up going through the board throwing my lame answers left and right, but I did. i figure what knowledge I have to share should be.

LOL I totally agree with ya.

no it will overheat on the highway, replaced the thermostat. you think it could be a faulty one? and put a new coolant temp sensor and that made it worse. if there is a blockage how would i go about finding it? thanks for all your guys help

well so far so good, i replaced the pump because i didnt seem like there was any water being pushed through. i would open up the bleeder valve on the thermostat side and just air would come out even when it was really hot. so since replacing it i've driven it to work a few days and no overheating, thank god!!! and i actually put the old sensor back in and it workes fine. i'll keep you updated, thanks for all the help.

Hello, I need help with this same issue too, the problem I have is that cooling fan doesn't turn on when it should, if I turn the AC on both fans are working so this means is not a relay or fan problem, I noticed that the temp gauge almost gets to the red square and then the fan starts working but this is not good, I have changed the temp sensor, the thermostat and the water pump already, not sure if Im still missing something or if I'm doing something wrong, what do you think I should do next?