hmm lets see.... First off you will notice a slight decrease in torque in the lower end and power in the high end around 5k
Vanos noise is often a good sign of a deteriorating vanos... not a failed one...
The DME has codes for a detected failed Vanos system.
Vanos noise is very fickle... most notice the noise while WOT after 2K rpms and when engine braking from 4.5K-2.5K. The noise is often refered and said to sound like a bunch of marbles in a tin can.
Fixes.... if your not getting the power you use to have... and your hearing the noise and its killing you and bugging you... there are things you can do...
A few of the often replaced parts for this problem.
There is the Vanos Selenoid.. its a little piston oil pressure operated selenoid that is known to often fail about every 60k miles...
There is the upper vanos chain tensioner... and lower vanos chain tensioner... also called the primary and secondary tensioner.... In theory the noise that is related to the vanos is the two chains... rubbing the case... thus a tensioner problem. Which requires access to the vanos it sell....
Now... those are the main replacable parts for this problem... or you can replace the entire unit...
There is another entire theory to this problem... noise... lack of power.. and thats oil vicosity... some say a heavier oil will help this problem.. and the others say this only hids a deterioration of the vanos unit...
Good Luck....
I couple good links for you...
http://www.realoem.com/bmw/showparts...82&hg=11&fg=15
that is a picture of the vanos unit...
www.m3forums.com do a search on their forums... a good search phrase I've used many times there is "vanos noise"... read all the information from past topics there for information on vanos problems...
Good Luck...
Les