Make sure you have all the air out of the system before you start replacing part$i changer thermostats with oem and i do not have flow when i pullet the heater core line it dribbled out and my lower hose is 75 degrees upper hose 202 degrees
To bleed it, fill the reservoir and leave the cap off
3,000 rpm for 30 seconds
idle for 30 sec
3,000 rpm for 30 sec
idle for 30 sec and so on
keep repeating until it reaches operating temperature.