oil relief valve info? 02 S60 2.4T

[jeffriehunter]

Have had oul pressure low light come on after engine had warmed and only at idle. So dropped pan for the 3rd time and removed the entire pcv system from air tube to oul trap and made sure.it is all perfect. Had the turbo rebuilt as well. Oil tube is sealed perfectly.

Here is my question........this time I removed the relief valve and decided to replace just because. Got the new one in today and you can blow through it in both directions? How does it actually work? Does the presence.of oil change how the valve works? I figured that it would be a valve that only opened under pressure.if the oil filter became clogged? I am just trying to learn......I am now a volvo pcv savant having removed and replaced this one three times now (we have also had some positive pressure). But found the turbo was malfunctioning so I also presume that if the turbo is not pulling air effectively then there is little vacuum produced in the air tube, thus creating no vacuum in the oil trap.

I am open to any and all insight on both topics and have been appreciative of the previous answers that helped me rework top to bottom correctly this time. Also replaced the oil pressure sensor this time. Have not yet finished the rebuild. Hoping to learn more an out this relief valve before I put the oil pan back on.