Can some tell me what the PCV system is in 2000/S40 ?

I had positive pressure...spitting little bit oil from the O/cap when removed.
A BMW mechanic suggested to change the clogged PCV 'paraferrnillia'[since there are $300 worth of cans and tubes...and a a dozen clamps and nipples and plastic elbows.].
So I had him fullfil his wish as he is a close friend of my son...and offered to do the Tbelt+Wpump.

He got the parts wrong except the black can, connected to crank case and two/three other places. So the can, and the hose from it[going to tappet cover] were changed.
All other lines, an alum tubing carrying vapors and also exchanging heat with another line[carrying engine coolant]...were flushed to ensure clear flow path.
After total assy back...No change in the +tive pressure was seen.
I don't get it...
A line coming out of this new container goes to tappet cover/oil-fill area where it seems to dump pressure...so how is that darn pressure 'relieved'..?
Black Cannister just collects the oil vapors and traps the gum/semi solidified junk...BUT doesnot seem to have a good size path /line to dump pressure somewhere.
Only a small vac line[2/3 mm id] is connected to the intake manifold...just to relive some pressure but NOT offer any flow.
The whole kabootle is elaborate ..yet doesnot seem to do what it is supposed to..
I am told that soon this pos prssre will push engine oil past some seals and create leaks.
My major question: 'Is the tappet cover area supposed to have NO POS PRESSURE..?"

Any suggestions....