2003 grandprix se temp

[tmuller02]

my coolant gauge is acting funny going from regular to over half to almost in the red my temp light not coming on and when it goes all the way up in like 3 seconds it will go all the way back to normal again andbelow half i dont believe it can goupthat quick then stay at a half then below half and then shoot all the way up again this is the regular engine not supercharged

[bombergp]

Hey Tmuller, When you post questions/problems tell us mileage your at & which motor you got too. Search info here on DEXCOOL. Its junk! Most likely gumming up your temp sensor in upper radiator. Look in the radiator filler hole, you probably see tan/brown goo eh? You must be upto 50k mi. now so its due. Dexcool doesn't last 100k mi as owners manual says. Flush it out with superflush cleaner and use Prestone yellow extended life coolant, it would even mix with dexcool if any remains in system.

[tblake]

Have you recently had any work done on the cooling system?

Sounds like there are air bubbles in it.

Fill up the radiator and bleed the air out.

[BNaylor]

Could be a thermostat problem. Sounds like it is taking longer to open or get to its regulating temperature and then eventually opens since your temperature does go normal based on your post.

On the issue of Dex-cool versus other Extended Life (EL) 5/150 coolants you can get the brown sludge dubbed the Dex-cool sludge even with the aftermarket coolants like Prestone EL. In reality the sludge is caused by combustion byproducts, engine oil or air getting into the cooling system most likely due to bad lower intake manifold (LIM) gaskets.

Finally, are your cooling fans turning on?

[tmuller02]

no the fans are not comeing on i dont think there comeing on because i dont think the car is overheating i think it might be a engine coolant temp sensor what are those chanches of it being like that and why aint my red temp light comeing on when the temp goes up

[BNaylor]

Didn't you mention engine temperature in the red? Cooling fans should come on in low speed at 220 degrees and hi-speed 230 degrees. Is this with A/C on or off? Fans should come on in A/C mode and high side pressure being over 190 psi, regardless.

You can check resistance (ohms) of the ECT - engine coolant temperature sensor to see if it is in calibration but the fans not turning on is a concern. Try this test. With ignition to off unplug the ECT sensor electrical connector. Then start it up. Fans should turn on in fail safe mode in around 5 seconds.

The PCM uses the ECT to determine engine temperature and turn on the cooling fans. The same ECT feeds the temp gauge at the dash instrument panel.