ok here go;s...i did a cambelt change on 2009 a4 b8 tdi 2.0,i renewed the waterpump,roller/idlers etc.
On this engine(i found out after id done the job) the sprocket bolts need to be loosened,so that belt comes off easy,and new one go's on easy,i did it the hard way,i fitted the belt,after 5 minute struggle(very tight fit) ,i then set the tensioner in the window,turned engine by hand twice,all lock tools went in ,indicating all is good.
ive since driven the car 400+miles........ive noticed only when on idle,if i rev the car say 1200 rpm to 2000 rpm i can hear a quiet hummin sound,it dont get louder as i rev up to 2000 rpm,and sound remains the same,after 2100rpm i can just about hear a very faint whine,at 2200-2400 rpm,i cant hear it
I know belt was a very tight fit,but ive read its quite normal for this to happen after a cambelt change,all genuine audi parts were used and every thing was torqued up.
Tensioners set ok,i thort belt mite be tight inbetween both sprockets,but the video shows thats not tight.

Belt dont seem tight when looking at it,is this the same with most belts?
2 PICS AND 2 VIDEOS BELOW.........ALSO WHATS THE BLACK STUFF ON THE ROLLER?,
[/B]MOV_0964_zps4af0d2b3.mp4 Video by vw754 | Photobucket
http://i851.photobucket.com/albums/a...ps5695db75.jpg
http://i851.photobucket.com/albums/a...ps451546d1.jpg
MOV_0942_zps9b76c637.mp4 Video by vw754 | Photobucket