started last week, Temp was hitting redline and i shut the car off with plenty of time before damage was to happen. now, the car was not losing any coolant. I replaced the 160* thermostat in there today let the car idle and still got close to 260 before i shut it down. the water pump isnt leaking or making any noise, is it possible it could still be bad?

 

Are your fans coming on like they should? I would also check the overflow and see if there is more coolant in there than normal. Also I would drain the system and see if parts of your water pump prop are in it. (Seen that before!!) Although I dono if Dexcool would allow that to happen?!?!?!?! If all that looks in order, I would check and tend to think that the temp sender is bad.

 

from your description it sounds like after the thermostat replacement, you only let the car idle and the temp it redline- that is most likely because their is either a little bit of air in the system and/or you had the radiator cap off while idling.
This is happened to me many times when I've done coolant or thermo changes on my 99 and on my 02. With the radiator cap off idling, it'll push coolant out the radiator and overheat. You will need to have the radiator cap on so the system will build pressure and air in the system will get forced out into the overflow tank. With everything buttoned up, disconnect the throttle body coolant hose and fill the radiator till coolant comes out that hose, then reconnect and fill the radiator as full as possible and install radiator cap.
Have the overflow coolant tank midway full and run the car up to temp at idle. you will need to let the engine cool, or use a towel and be carefull when removing the radiator cap. It might take you 2-3 times refilling the radiator as air pushes out the system and fluid level drops in the radiator, it should burp air out into the overflow tank and pull coolant back in from overflow tank but you need the system nearly full to begin with for that to work.

i doubt the thermostat is bad, but you never know. it will however not matter if you do not have a radiator cap on that is functioning and allowing the system to build pressure.
you might also have a faulty radiator cap, you'll know that if when you try to remove it when the car is hot and coolant wants to blow out and burn you- if that does not happen then good chance the cap isn't sealing. don't burn yourself obviously.
other than that, only thing left is water pump and if it's turning and not leaking then it's most likely working. with engine fast idle and hot with system under pressure, you should be able to squeeze upper radiator hose by hand and feel coolant surge, if you don't than start looking into why coolant isn't being pumped... again you need a good radiator cap and system under pressure.

 

alright here goes, after letting the car cool the first time i took it up the street at 55 mph (3200 rpm) the car almost immediately jumped to 260, i pulled over andshut it down and carefully and slowly opened the cap to let air escape, let it cool, drove the car back at the same speeds, this time the car did not go above 230.

Got the car back to the apt and let it idle, not going above 230 again. (seemed i had an air pocket and things started to work itself out on the drive, there was fluid in the hoses and i had pressure again.) i carefully removed the cap and level was high and pretty hot.

checked my fans and one was on but the other wasnt, i took my starter relay(same relay as the fans) and swapped it in with the fan relays and the other came back on.

so i just got back from gm with the new relay and also a coolant temp sensor (just to be sure)

 

sounds like a winner

 

turns out it the problem was the fan relays. thanks for the help!