Rather than buy a Stant or off brand Coolant pressure tester
https://www.summitracing.com/parts/snn-mt300
I fabbed a hose with a valve stem end and attached it to the expansion tank port. I pressure test at 15-20 psi., leave it pressurized at least 20 min.
If you want to vacuum bleed all the air out of the cooling system you can buy a kit like this.
https://www.summitracing.com/parts/oes-24444
Or pull the schrader valve from the valve stem and install a dead-head (no pressure relief valve) radiator cap like I use on my Recovery tank.
https://www.summitracing.com/parts/snn-10203
Take a 10 min break and no more air in the cooling system. You may have to do it more than once.
