Please excuse my ignorance, how will pressure testing locate the issue (genuine question)? I understand that you can pressure test the cooling system and if there is a leak the pressure will slowly go down. How would I locate where the leak is? Do I just assume that if, under pressure, no coolant is visible on the ground, it must be into the cylinders, thus it is the head?
I also know of
chemical testers that can test the coolant for CO2 which can show if you have combustion gases seeping into the cooling system. Wouldn't this be a more useful test in this instance?
Asking this, as I am having a similar issue to the OP, but haven't yet replaced the Oil Cooler.