I've been suspecting an issue with the PCV system in my Opel Astra H 2008 with a Z14XEP petrol engine. It blew both the oil pressure switch and (probably, have yet to investigate) the front crankcase seal in short succession.
I tried the old "balloon on the oil dipstick tube" trick, which seems to show significant positive pressure inside the crankcase, even at idle.
The video was taken at idle. I think I can feel individual cilinder pulses in the balloon.
How do I fix this issue? I checked the rather large hose going from the valve cover to the T junction before the throttle body and it's not blocked.
Some additional information: the engine oil cap is always caked with a mayonnaise like substance. This is apparently rather common on these engines and not indicative of head gasket failure. The engine oil does not contain coolant.
Do I need to install a new valve cover?
Edit: I found some related material: here. It's not the exact engine (1.6L instead of 1.4L) but it's close. I checked the hose that connects to the intake manifold and that's definitely not blocked (lot's of vacuum).