How do you test old style pcv ?

I was not sure if the test as a pressure or vacuum test and what are the specs. Like the newer valves that have a spring and the spring wears out and the pcv leaks. That valve can be assembled with a multitude of springs rates. This one seems “looser” than others. I also want to put a gauge on that port to see what type of vacuum the engine is pulling and see if maybe the engine is pulling more vacuum than the pcv can handle and it is staying open always. In which case it’s garbage and I need to find a new way to evacuate the crank case.