Hi,

I just replace the components of my PCV (Positive Crankcase Ventilation) system this weekend on my 260000km S40. You do not necessarily need to renew things like me but I choosed to do it for piece of mind (but this involve a bit of job since the intake manifold has to be removed). However what Volvo means by PCV maintenance is simply to blow compressed air through the PCV hoses to make them "clear" (our cars are not fitted with flame trap). Of course you need to drain the oil right after since you'll probably push some sludge etc back in the crankcase and sump by doing this.

You should have 2 PCV hoses on your engine: one on the top of the engine close to the oil cap and that is clipped where the spark plugs are located. The other hose is a large tube that is connected to your air intake duct right before the throttle body. You should unclip both hose and blow compressed air in them and then reconnect them as they were before. There is a 3rd hose to clean this way, it's a small pipe that is right beside the PCV hose connected to the air intake duct. This small pipe allows vacuum from the intake manifold to suck gasses of the PCV system at idle. You should also disconnect it and blow compressed air in it. Reconnect everything....and don't forget to change the oil after that!!

This should "assure" that the hoses are not blocked by sludge. However even if they are not clogged, their walls will have some oil residue that may slightly restrict the flow of gasses which is not very good. Your only option then is to renew everything as I did. This was probably not required but I prefer doing this as I plan to keep the car for a while.

Let me know if you need pics.