Originally Posted by B serious

Did you open the bleeder while adding coolant (engine cold and turned off)?

Here's my process which has been bulletproof for me.

Assuming the car is already parked on a flat surface or nose up on an incline.

I turn the key on (engine off) and set the heater knob to full hot and wait til I hear the blend valve completely open.

Shut off the key

Insert coolant bleeding funnel.

Crack open the intake manifold bleeder AND the heater crossover bleeder (rubber cap).

Fill the coolant via the funnel.

Keep filling until a solid stream of coolant comes out of each bleeder and cap/close it when that happens.

Fill the funnel about 1/2 to 3/4 way up with coolant.
Fill the overflow reservoir to its full mark and cap it. Make sure the overflow cap tube is on and is submerged.

Start the car and run the heater at full blast. Monitor the coolant temp gauge to make sure the car never overheats.

Wait for bubbles to stop. Wait for hot ass heat in the cabin.

Turn off the engine, remove the funnel and cap the radiator

Go for a short drive. Make sure the heater is blowing hot and the car isn't overheating.

Park overnight.
Wait for it to cool.

Check the reservoir level and top off as needed.
Check the radiator level and top off as needed.

Confirm hot heat and proper coolant temp on your gauge on the next drive.