Made a combustion leak check today (exhaust gases in coolant).
Bought this thing from Amazon for 36$.
https://www.amazon.com/gp/product/B06VVBSFTF/?tag=wranglerorg-20
Opened the radiator cap. Drained the fluid from the radiator slightly (like 3 inches in radiator) using the drain valve on bottom passenger side of the radiator.
Then started the rig, brought it to 210F, and run it there for 5 minutes. Verified the thermostat was opened, and fluid ran through the radiator.
Then used the leak tester, pumped it for like couple of minutes, the fluid stayed as blue as ocean.
Was happy to know that my head gasket is fine, and that it does not leak at all.