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I stopped at a railroad crossing for a train and decided to check the stats on my new 2010 Cobalt LT Sedan. I was shocked to see the temp at 219 degrees farenheit. That seems to be WAY to hot as my old 2006 Cobalt LS Coupe was quite steady between 199 and 205 degrees. This new Cobalt is all over the place running from 185 degrees to 205 degrees running. Let it idle and the fan doesnt come on until the temperature is around 217 degrees. Mind you it was a fair day with the highest air temperature at 63 degrees farenheit. If the car is running this hot on such a mild day, whats going to happen when we get sizzling hot days in the 90's to 100 with high humidity?? Could this be a faulty thermostat or temperature sensor? Am I just being paranoid here? I asked an "online GM mechanic and this is the response I got

"Hello, and welcome. the normal operating of the engine should be between about 185 to 220. the cooling fan wont kick on until,223 degrees for low speed fan operation. your temp reading that you are getting is well within its operating range.

The PCM commands Low Speed Fans ON under the following conditions:
• Engine coolant temperature (ECT) exceeds approximately 106°C (223°F).
• A/C refrigerant pressure exceeds 1 310 kPa (190 psi).
• After the vehicle is shut off, the ECT at key-off is greater than 140°C (284°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.
The PCM commands High Speed Fans ON under the following conditions:
• ECT reaches 110°C (230°F).
• A/C refrigerant pressure exceeds 1 655 kPa (240 psi)."

The fan is not supoosed to come on until it reaches 223 degrees?? The temp when the engine shut off can reach 284 degrees??? That seems WAY, WAY to high since dexcool boils at 260. Meethinks its time to take my 2010 Cobalt back to the dealer and have them take a look. I DO NOT want my car overheating nor do I want to do ANYTHING that would void the warrantee which overheating would probably do. Anyone have any thoughts on this??
 

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No its perfectly normal.. Dont worry, a lot of us have freaked out the first time we were idling in traffic and noticed our coolant temps :amuse:. Sometimes in stop and go driving and idling right after driving the coolant temp will rise to 215-220 because of a lack of airflow. Personally I dont like seeing it go up that high, so I just turn my AC on full for a minute and it turns the secondary fan on- which cools things down in a hurry :idea:.
 

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That seems WAY, WAY to high since dexcool boils at 260.
That is the boiling point when at normal atmospheric pressure. When it is under high pressure, like in a cooling system, the boiling point is increased.
 

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Boiling point increases by 3 degrees for every pound of pressure you put it under.

Oh...... OP, I have seen 220
This is still freaking me out. At 220+ I think I would have shut the engine down and called AAA for a tow. I dont like this, not at all. Why cant this new Cobalt behave like my old one?? I should have bought it out at the end of the lease instead getting a new one.
 

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I stopped at a railroad crossing for a train and decided to check the stats on my new 2010 Cobalt LT Sedan. I was shocked to see the temp at 219 degrees farenheit. That seems to be WAY to hot as my old 2006 Cobalt LS Coupe was quite steady between 199 and 205 degrees. This new Cobalt is all over the place running from 185 degrees to 205 degrees running. Let it idle and the fan doesnt come on until the temperature is around 217 degrees. Mind you it was a fair day with the highest air temperature at 63 degrees farenheit. If the car is running this hot on such a mild day, whats going to happen when we get sizzling hot days in the 90's to 100 with high humidity?? Could this be a faulty thermostat or temperature sensor? Am I just being paranoid here? I asked an "online GM mechanic and this is the response I got



The fan is not supoosed to come on until it reaches 223 degrees?? The temp when the engine shut off can reach 284 degrees??? That seems WAY, WAY to high since dexcool boils at 260. Meethinks its time to take my 2010 Cobalt back to the dealer and have them take a look. I DO NOT want my car overheating nor do I want to do ANYTHING that would void the warrantee which overheating would probably do. Anyone have any thoughts on this??
Low speed kicks on at 217* and off at 190* which is the stat temp. There's no air moving through the radiator at idle so it'll always reach 217 if you idle long enough. I haven't seen the high speed kick on yet but if it's anything like my maro high won't kick on until low 230's.
 

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just a bit from a tuning book I once read.
if you could isolate the intake manifold from the engine heat
to prevent the heating of the intake air and run your engine between
215 - 230 degrees F, you will experience the lowest specific fuel consumption
while obtaining greatest engine power output.
 
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