w211 E63 rattling noise from engine bay
 

So I had my car parked for about 2 weeks in the garage. I drove it all day everything seems good aside from this one rattling noise coming from the pulleys. Is it something some lubricant can solve, or does it look like my pulley is on the way out?
Thanks

It's one of the pulleys. Lube isn't going to help. Get an automotive stethoscope and pin point which one it is.

Thanks Rocman

ya one of the pulley bearings is shot. change it ASAP or it could cause your belt to jump.

will do hachiroku thank you

Weistec sells a complete set for our cars 5 pulleys, check out their website.
Have a set on both our cars and they are 1000% better than the plastic MB crap.
How they expect an engine than turns 7k rpm to survive using meltable plastic pulleys after about 30000km.
Bearing overheats and melts the outer race and you are sitting on the side of the road with a torn off serpentine belt and a tow bill.
Buy the complete CNC aluminum set with replaceable bearings The Best :)