Engine Coolant not reaching operating temperature in colder weather

[padosd]

I have been experiencing an issue where when it is cold outside, below -2 Celsius (28F) the engine does not warm up to operating temperature even after an hour drive (highway and city driving). Usually when it is above zero Celsius outside, the vehicle reaches operating temps and hovers around 94-96 C (200F) for the coolant.

Below zero outside, and it hovers around 70C (158F)

I am attaching a scan of the engine from cold soak to 20 minutes. At 13 minutes in it starts to just hover at 70C (158F). No matter the length of drive.

https://www.dropbox.com/s/l6jx7pfu7l8fu4e/BlueDriver DataLog - Coolant.xls?dl=0

What is also interesting that I if I turn off the heater for the cabin, the vehicle will reach operating temps. Once that happens and I put the heater on the highest setting, the coolant temps will go back down to 70C (158F) while driving. This happens even under load like going up a hill. Once the coolant temp drops, there is less heat pumped into the cabin for obvious reasons.

Dealer already tested the thermostat and they said it is operating normally. They said the vehicle is operating normally.

I would love to know how other Yukon's function in cold weather with regards to coolant temps.

 

[gemarsh]

Yes. Had to go old school and put a piece of cardboard in front. Would rather do that than have a heating problem in the summer and not be able to cool the cabin down.

 

[thebishman]

I have the exact same truck as you.

This morning it was 40dF in the garage when I started the Denali, and 23dF outside. It was up to '185dF' on the temp display within a couple of miles and loads of heat was already warming up the cabin. (My truck gets toasty warm rapidly).
Within a few more miles, still at the same ambient temp, the truck was at it's normal running temp of around 210dF.

If your Denail is running at 158dF, then I'm betting the temp sensor is broken, as this is NOT SOP. If the heating system is working though, then I bet you're getting up to the correct temp, but the sensor is at fault.

Find a new dealer if they won't fix it would be my advice.

Bish