New to me 2008 HHR LT2 with 43K miles. The coolant display reads 212-230 when pulling hills in AZ with 110+ ambient temp. The needle gauge moves from 1 mark below halfway to almost halfway. My other GM cars have a large dead-band for the needle gauge so it always stays in the center. My question, does the needle gauge and coolant temp readout get their input from the same sensor? I was thinking I may have a bad sensor if they do not. No loss of coolant and no boil over. I backed down in speed when the temp reached 230 and it dropped to the low 220's. and continued to drop after the hill. Around town it runs 205-212 in stop and go traffic with the AC on. Under no load/coasting it drops to 192-196 at city speeds. Any help is appreciated.

 

Depending on the "hills" you are speaking of, it may be normal. For example, running up to Flagstaff on I-17 and encountering Sunset Point I had experienced the same temps as you. In fact many Arizona people have witnessed the same readings in the same area.....and others as well.

The analog temp gauge is a worthless piece of equipment as far as I an concerned. I have never seen it climb above the half way point and my digital temperature was indicating 235. I drove (the vehicle is now sold) my HHR with the DIC display on the digital engine temperature ALL THE TIME.....it's kind of a piece of mind.

One of the other "things" I have noticed (and also been told) is the water pump is inadequate for AZ temperatures, especially at Interstate speeds. If you lower the speed 5-10 mph from the 70 or 75 you'll recognize slightly lower temps (5-10 degrees). I've experimented with this 100's of times and it has worked every time.

Now if you are speaking of the gradual hills experienced on the Interstate through the valley, I withdraw all the statements except the lowering of speed and the function of the analog gauge.

Oh I might add.....have you checked the level of the coolant and if it had been changed as suggested by the Owners Manual. If not, you are overdue.

 

The transmission fluid may be adding heat to the coolant in those conditions. You might consider an ATF cooler.

 

'08 ? Time for a new Tstat and Dexcool

 

Thx for the feedback. Coolant level is fine and looks new, however I will change the coolant and thermostat for a known baseline. I will check into a trans cooler.

 

Be sure to get a GM AC Delco 180 degree T-stat and use proper 50/50 Dexcool.

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