squealing noise

Hello, my first post. I have a 2017XC90 Momentum 2.0 tr. It has a squealing noise around upper cam gears after driving a short period. I replaced the oil trap with pcv diaphragm on top of valve cover, still makes the noise. So then I replaced the pcv check valve at rear/drivers side of cylinder head and it still builds so much crankcase vacuum it makes the squealing noise as bad as in the beginning. I am stumped?? do you guys have any insight? Thanks in advance.