I have an 06 ss sc with 65k on it. During winter noticed that my coolant temps steadily got colder till they wouldnt hit above 150 ish. Then it threw the thermostat rationality code p0128 so I swapped out the thermostat with a gm one and bled the system about 3-4 weeks ago.

Note: its been in the 50's here lately maybe 60's.

now my car is running warmer but I never hit over 176-178 and thats when im at a stop, accelerating it will fluctuate quickly and all the way down to 168ish. I was in the drive thru and it got to 185. At work today I picked up the front end and let it run for a while with my coolant funnel on the reservoir and it did get to 225 and appeared to bleed some more air, let it cool again and did it again with the same results so I figured awesome more air out thats gotta be it. Nope on my way home did the same thing and never hit above 176.

Im wondering if I have a clogged radiator? Ill try pulling the hoses tomorrow and reverse flushing the radiator. Any other ideas it could be or try?

Thanks in advance, Ryan.

 

If your radiator is clogged youd be overheating instead of overcooliong....

I still think your thermostad may be bad....

If your radiator is clogged youd be overheating instead of overcooliong....

I still think your thermostad may be bad....

 

What temperature rating is the tstat youre putting in?

OE calls for 180 and that should put you at 185-190 at idle. Its impossible for it to be lower unless the gauge is reading wrong.

 

If you still dont have any air....Id get the ECT checked out...might be throwing some bad info....could also be some air in the heater core...check the radiator resivor cap.....

 

Maybe the thermo got put in backwards by mistake?

 

The thermostat was an oem ac delco one, i checked the part number with crate engine depots web site and it matched. i know doesnt rule out crappy tstat built from factory though.

the weird thing is that my upper rad hose gets hot like it should and my lower hose is cold to the touch.

 

I don't think you can put it in backwards...I tried flipping it to see if you could and it hits the housing(at least on the 2.4l)...I would guess either a bad sensor or another bad stat.

Btw Ive seen your car a few times Racine...unless you've seen that same color SS around too.

 

haha yeah i think i have seen you, you may have been behind me the other day on KR i think it was? yeah the tstat wont fit upside down i tried too. well it was only a month ago so if the new one did crap out already ill try that i should be able to return it seeing as I work for the dealership I bought it from. ugh that thing sucked to put in too.

 

Thermostat is likely stuck partially open. Overcools when driving because it is open too much for conditions, undercools when idling because less air going past rad.

 

This forum is full of retards. They offer advice when they clearly know nothing about cars. Every other thread, it has some idiot throwing a guess out there. Every cobalt owner I have ran into knows nothing except for 1 who agrees with me that this forum is full of asshats.

Like this guy above... completely clueless. Reads symptoms and just throws random crap out there.

Im all set with the forums here. Way to make a name for yourself cobalt owners. Speacially that gremlin tuner guy who tunes via narrowband. Wow this place is a waste of time.

 

Lol. This coming from someone who said our cars were tuned by speed density because he couldn't find the MAF in a previous thread.

 

I agree with startingline. You don't even know what sensors are what or where they are and you are trying to tell other people they are retarded You must work in a gm service department