I did the heating core first. I pulled the hoses, put a bit of detergent through it, and a bunch of water from the hose. Next I drained the radiator, and then, leaving the drain screw open, I put a hose flowing into the rad fill neck and ran the car with the heater on high for about 20 min, until only water was coming out of the drain. then I shut the drain screw and put in the detergent with the water for another 20 min. Last, I opened the drain bolt again and ran it with the hose running in it again for 20 minutes to rinse out the detergent. Then I turned the hose off and pointed the nose of the car down to drain the radiator and as much of the car as I could. I filled the radiator back up with concentrated coolant (I assumed that there was still mostly water in the system throughout the car, I'm hoping the mix ends up about right...), ran it for a bit, then topped off with 50/50. Then bled, topped off, ran, bled, etc.
I have bled it and bled it, and it always seems to have more air in it after it runs 210 degrees or hotter, and I mean a lot of air. Check out this video: https://youtu.be/mGQl3cc3w6U
