Hi guys
Looking for some help. I have 08 audi a6 2tdi. When you turn the engine off after a drive it makes a noise from engine.... theres a hissing noise from a round black thing on the head oposite the where you put the engine oil in but also a buzzing noise like when your door is open then goes pop pop.....

Any ideas...?

 

Ive been told the thing where the air is coming out of is called crankshaft breather valve?
Can this be cleaned?