Hello guys this is my first post on this forum. Recently i bought Volvo s80 D5 2007. The car drives just fine but, while at idle or at smaller speed i can hear a hissing sound whenever i press the gas pedal. The sound is very similar to turbine acceleration sound but i don't think its the turbine. Also i think the noise is louder when the engine is cold. Does any have any similar issues, what could be wrong?
Here is a video of the recorded sound

Thanks

 

try pulling out the dipstick a bit with the engine running - does the whistle go away? If it does, you could have a clogged PCV system

 

Thanks for your replay, i've opened a bit the dipstick but it doesn't change anything. I've uploaded a video of the sound -

 

Anyone?