Overheat, lots of new stuff

New thermostat, radiator, radiator cap, water pump, hoses, viscous fan.

No freeway driving, just surface streets.

Go down a hill to work, come back up the hill and overheat.

When car gets hot, can turn on heater, dump excess heat, and temp gauge moves back towards center.

Oil is clean. Coolant is clean, no oily residue.

Thoughts?

Try this.

Get the engine up to operating temperature. With the engine idling, loosen the upper radiator hose clamp and slip a small flat bladed screwdriver between the upper radiator hose and the neck on the radiator. Allow the engine to continue to idle until all the air is purged out of the cooling system and nothing but coolant comes out. Pull the screwdriver out and retighten the hose clamp.

Tester

The latest item I replaced was the water pump today. Afterwards, I got the car up to temp with the radiator cap off. Wouldn’t that have the same result as was suggested?

Nope! With the radiator cap off the cooling system isn’t put under positive pressure. Putting the cooling system under positive pressure forces the air out of the cooling system when bled from the upper radiator hose.

Tester