Ok guys I have a 06 HHr LT, it has 32,000 mile on it bought it brand new in 2006, I have had my radiator flushed, new thermostat replace, and my Temp is fluctuating between 226 to 241, there are no leaks showing, Antifreeze is good, so now I'm thinking that I need to replace the cooling temp sensor, what else could it be beside the computer is faulty, I love my HHr, but now I'm thinking about getting rid of it , I also saw that to change the sensor, that you need to remove the driver side tire, and wheel cover to get to it.

(Split this off from a "Dead Thread")...843de/Mike

 

First things first,
1. What Thermostat do you have? The answer should be GM AC Delco, the aftermarket stats can cause this issue!
2. What coolant or antifreeze did you use! The answer should be Dexcool 50/50 mix, the green stuff does not play well with Dexcool and can clog the heater core causing a blockage to stop the cool effects of the radiator!
3. Do you hear a gurgling noise in the heater vents, indicating air in the heater core.
If so park your HHR grille higher then the other end , even 6 or 8 inches let the car cool, remove the coolant ( rad ) cap nd start the HHR turn the heater to full heat run the HHR for 10 minutes, let it cool and top up the coolant in the hose , replace coolant cap.
You may need to do this a few times.

 

..............and does your cooling fan(s) ever come on? they should come on when the A/C is turned on.

 

X3 to the above, 226° to 241° is in the Death Zone on Ecotec engines, they Will Not tolerate those temps for long without suffering damage.

And it may already be too late, check all of the above, and barring that....get thee to a competent tech or radiator shop poste haste!

 

Ok I have replace my thermostat, coolant, cooling Temp sensor, and still my 2007 HHr LT 2.4 still is getting up to 242, I'm trying to figure this out, I was told about 2 years ago that my oil coolant line was leaking, but never seen anything dripping, so I'm wondering if that could cause the temp to go up, I have the lines, just need to get it in, my cooling fans are running also.

 

Its located right next to the thermostat, on the back side and up a little bit, you can feel the wire that goes to it, I had to do it blind, because I did it from the top, so I felt where the wire was, it has a oblong feel to it.

 

He did that back in 2011, probably needs it again following the 5 year rule! My 2007 is now 9 years old, original coolant temp sensor, replaced the T Stat 4 years ago and the Dexcool!
Will do it again next year, when it's 10 years old!
Please remember to use an AC Delco 180 degree thermostat and Dexcool!

 

The water to the oil cooler may not show as a leak, steam more likely.

Have you bothered to check the coolant level, both in the tank and under the pressure cap. I don't remember if the 2007 2.4L has a surge tank or a bottle. Surge tank you would not need to remove the cap.

Low coolant level can cause overheating!! If you have been letting it get to 242F for ANY length of time there is a good chance head gasket is damaged. The dashboard didn't light up like a X-mas tree, the car didn't start bucking, the trans didn't start hard shifting?

 

Well I have a 2006 HHr LT 2.4 32,005 miles, and mine hit at 242, I have change the Thermostat, coolant, coolant temp sensor, fan is running, and run for a few second after shutting it off, and it still run up to 242, and they also told me that I have a trans oil coolant line leak.

 

In your other post on the subject (please stick to only one) you said it was the oil cooler leaking. The transmission lines run into the radiator to cool the ATF. on a 2.4L there is an engine oil cooler where the oil is cooled by water.

If coolant is leaking from anywhere that is the problem. You should be checking the coolant level frequently.