Hi, sorry I assumed you had already changed those with the valve cover gaskets.
Have you popped the caps off to see the diaphragms? You should have a hissing noise from the dipstick hole if you remove it. Not if the dipstick is in though!
2008 F01 - Sophistograu with Saddle Brown Leather
Night Vision, Digital TV, Heated M-Sport Steering Wheel + Paddles, Combox, 6NF Baseplate, 6NR Apps, Rear Entertainment System, Automatic Boot Close and Surround View Cameras.