Is my thermostat bad?

[Cryptothedog]

I just bought this 2015 Suburban LT about 3 weeks ago and I feel like it should be running hotter than it is. It seems to stay right about the line above 160 or the 1/4 line on the gauge. My 2004 suburban ran right about half way. Is my thermostat bad or do these newer ones just run cooler?

 

[B-train]

Yes it is. Common failure. The thermostat has 2 stages to it and the smaller spring section stays partially open. Easy fix, 2 gallons or less of coolant for what you spill out, and about 30 minutes of time.

 

[mrathell]

Yep, changing the thermostat should fix that issue. Also it is possible the previous owner installed a thermostat designed to open at lower coolant temps resulting in the issue you are seeing. So make sure you get a genuine GM thermostat.

Here is a video I made of me changing mine: