Thermostat replacement

[Bagherra]

Help!
Just replaced thermostat with GM part. No heat unless I turn temp to HI and gsige reads constant 210.

What did I do wrong?? Followed steps on YouTube vid...

 

[Joseph Garcia]

I suspect that you have residual air in your cooling system. I suggest that you re-do the air bleeding procedure and get the trapped air out of your cooling system.

 

[Bagherra]

Can u please explain how to do that?

 

[Joseph Garcia]

@Doubeleive @wjburken @OR VietVet

 

[Doubeleive]

Can u please explain how to do that?

Stand on the running board, grab the roof rack if you are tall enough and rock the truck side to side a bunch of times, Jack the front up a little bit, check the reservoir level, start it up and turn the heater on full blast and let it idle up to operating temp (WITH RESERVOIR CAP OFF), when the thermostat cycles, fill the tank again.. if it idles at normal temp and the tank is full put the cap on and drive it spirited while driving make quick left right turns/swurves several times. Like you are driving a obstacle course. Then stop and recheck the tank level, top off if necessary. Then you should be golden

 

[OR VietVet]

What @Doubeleive said, but what I do when adding coolant after work like this, is jack up the passenger side and fill real slow and let sit and the level typically goes down and then top off and run it and monitor and then top off and then run the crap out of it and rock it left and right when driving and top off as needed. Or get a vacuum fill kit.

I am curious about 1 thing though. "WHY WERE YOU REPLACING THE THERMOSTAT TO BEGIN WITH"?

 

[Bagherra]

What @Doubeleive said, but what I do when adding coolant after work like this, is jack up the passenger side and fill real slow and let sit and the level typically goes down and then top off and run it and monitor and then top off and then run the crap out of it and rock it left and right when driving and top off as needed. Or get a vacuum fill kit.

I am curious about 1 thing though. "WHY WERE YOU REPLACING THE THERMOSTAT TO BEGIN WITH"?

Gauge would drop to zero and fans would run...replaced temp sensor, worked but problem came back. Everyone said replace thermostat and problem would stop.

 

[L8T BURB]

In addition to the above recommendations, be sure to scan for any stored codes. The failure you're experiencing prompts a stored code for "coolant temperature below threshold". If not cleared, there are cases where symptoms can still linger. Be mindful that in a lot of cases, this stored code will not illuminate the check engine light, but it is stored in the ECM.

If you do not have access to a scanner, removing the battery cables for about an hour might also do the trick.

 

[Bagherra]

I did scan and cleared codes.
Thanx for the responses!