Hi, I'm after some help.

I have a 1.6tdi octavia estate which has just started to make a whistle type noise when the engine is warm, the noise goes when you remove the oil filler cap.

I have done some research and come up with possible pcv/ rocker cover valve and will require a new rocker cover. Anyone else had this and does it sound right?

Does the noise go when you accelerate? And is there some kind of suction when you try to remove the engine oil cap?