Air stuck below thermostat

[normark]

Temp gauge rises a lot. Top of radiator hot. Bottom cold. The termostat worked fine before I flushed the cooling system. I tried to pour the new coolant in slowly. I tried to run the car with rad cap off but no air gets out.

So I guess that there is air stuck below the thermostat that hinders the termostat from opening.

Is there any other way to get rid of this air than removing the termostat and put som new coolant in place?

I've tried to search the forum for bleeding procedures, but all seem to relate to the external thermostat. I only have the internal as in the pic below

Also, I read something about drilling a hole to let air out. Is that applicable for the internal thermostat as well? Or is there any other way to do it? If there is a risk that the heater will work less well with the hole I rather find some other method - I live in cold climate!

[azruss]

make sure you didnt put the stat in upside down. While you are in there, bench test the stat. If they go dry, they can stick as there is usually some coating on the valve shaft that need to be cleaned off. I've never seen air trap under an internal stat.

[vandor]

Yes, a tiny hole in the in-head t-stat is fine.

[normark]

Faulty temp sensor...

I installed a new one just to be sure but that was clearly a bad decision. Now I'm back to the old one and everything works as it should. Looks like there's some psychology involved here. The thermostat was never near opening temp but when the gauge shows nearly red the engine sure feels very hot... I used a infrared temp gun just to be sure everything was alright