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- Hummer H3 (https://www.hummerforums.com/forum/hummer-h3-17/)

- - Car getting hot. (https://www.hummerforums.com/forum/hummer-h3-17/car-getting-hot-41590/)

Quote:

Originally Posted by WR3NCHE4D (Post 362360)

Just like to add that the old thermostat could have been opening much too soon. This is also common with the H3's I5 Atlas engine. There have been many thermostats changed due to no heat in winter and check engine lights. My temp gauge running under half because of this. The old failing thermostat running cold compared to new stat operating properly. I have checked my gauge with a quality scan tool and at 3/4 it was reading 207°F after bombing down the highway and coming to a light. Just a reminder that pressurized coolant boils at over 220°F. If my idiot gauge doesn't go to the red everything is fine, just like the Doc said. Drive on.

It's time to replace the cts.

A 50-50 mix should boil at 223* unpressurized . With the 14 psi radiator cap that number goes up to 265* and if you swapped in a 17 psi cap it will go to 275*.
The gauge on the 2008+ vehicles have been dumbed down intentionally on the H3 (was done on other makes earlier, check trail blazers, silverados, etc...) so people are less anxious about any fluctuations in temp. The new gauges will read a hair below half between 192 and 224*, half at exactly 225* and stay pegged there until 255*

Quote:

Originally Posted by NFS (Post 362313)

Hello, I have a 2007 Hummer H3. I had a cracked radiator so I replaced the radiator, also replaced the thermostat and made sure to add the right dexcool and got the air out.
before my radiator cracked and started leaking the temperature was always under the half mark. now the temperature is always raising between 3/4 and little less.. which I never seen it goes that high before. if the car is off and I start it, the temperature gauge will be at 3/4 then it goes down to like the pic I attached which is little below 3/4 and kinda stay around there. no matter what the temperature is 70 or 90 its the same. I live in florida and it gets really hot and humid so I wanted to figure this out before we start getting super high temperatures. the new thermostat that I installed is gates 34045 which open at 187 they say. I don't know what's the opening for the stock I heard 190?? but could it be the thermostat is bad? because if it open at lower temperature then it should be less than the half mark for sure...
https://cimg4.ibsrv.net/gimg/www.hum...002303ddc.jpeg

Perfectly normal. My H3 has been running like this for 6yrs/75,000 miles. And don't scare yourself and look at the gauge if you shut off the engine for 2 minutes and then restart, the gauge goes past the 3/4 mark. But it's all perfectly normal.

I just purchased it a few days ago. 2006 Hummer H3 Adventure package. 177k miles. The temperature always seems to stay in between 1/2 and 3/4 mark.. I hope it's not a problem with the cooling system...