Help identify engine whine

[FireFox31]

Hello, can you help me identify the source of this whine from the engine bay? The car is a 2008 XC70 with probably over 150k miles. Here is a video of the whine (caution, it's loud and shrill).

It's a high pitched whine coming from the belt area of the engine. It starts after driving for 45 minutes. The pitch does not change with speed and it continues at idle. It stops under acceleration. It didn't change when the A/C was turned on.

Is there any other way to identify which component is causing this? I have a stethoscope (long metal rod with ear phones) but I don't see easy access to the belt area without removing the air intake (turbo hose?) and battery.

Thanks for your input.

[pgill]

Remove the oil fill cap.

If that changes the noise then replace the PCV.

Good luck

Paul

PS for my 2010 S80 3.2 I bought an aftermarket PCV with the FOMOCO marking for about half what Volvo wanted (same part except the blue VOLVO Box). Get one of these if you do replace it.