Air locked cooling system

After replacing the water pump and t'stat in my 1990 GC 3.3l I am overheating badly. Seems like there is no coolant flow. Is it possible the system is air locked? Prior to replacing the water pump (leaking out the bearings) there were no overheating issues.

BTW, the van is parked slightly down hill when I did the work and refill.

Thanks for the help-if you can.

Yes the system is probably air locked. Place the van on a level area and remove the radiator cap. Make sure the radiator is full. Start the vehicle and when the thermostat opens you should see a drop in the coolant. Refill it and allow the engine to run. Continue to watch the level. Continue to refill until the system is full. Replace the radiator cap and check the guage. The system should be fine.

Yes the system is probably air locked. Place the van on a level area and remove the radiator cap. Make sure the radiator is full. Start the vehicle and when the thermostat opens you should see a drop in the coolant. Refill it and allow the engine to run. Continue to watch the level. Continue to refill until the system is full. Replace the radiator cap and check the guage. The system should be fine.

I parked with the nose facing up a grade plus drove up on blocks. Still overheated after refill. Took out the new T'stat, flushed radiator, flushed at T'stat, refilled with water only and no T'stat. This time I got lots of air bubbles, but it did not overheat. Not sure if there was a small blockage in radiator or block cooling passages, but it seems fine now. I checked T'stat operation using boiling water and thermometer. Works fine. Will re-install.

Thanks for responding!