I’ve only worked at a VW shop before and I saw it happen from time to time, they were plastic impellers tho. I really don’t know how common it would be on other makes.
We would remove the thermostat and stick our fingers in the hole and see if the impeller would free spin.
I am with the Honeybadger on this,
An air pocket is a very common cause for overheating.
As for the head gasket issue.
Is this a coolant loss issue??
One must deciding how much to invest in a repair and if the cost is just to high for the life expectancy of vehicle then what i have done is used one of the many Hocus-pocus (Mechanic in a can) products on the market.
I had an excellent outcome with a coolant loss issue that caused overheating by using a “Block Sealant” (Not Radiator) that had metallic particles in it.
That old Buick is still on the road 5 years after.
This link is not the product i used as i didn’t find the one but it is very similar.
Thank you. Draining and then adding new coolant seems to have worked.
Fixed the head gasket too?
The simple case is coincidence, and its a sticky thermostat.
