[sb01box]

i posted a thread where I thought it may be my DMF starting to rattle. but found that it was the alternator pulley not working. the one way slip was broken and acted like conventional pulley. during deceleration, the alternator momentum and the crank was playing havoc with the belt tensioner. In my case, it was not squeaking.
I'm guessing that if your car is squeaking, you need to check all the components that the serpentine belt drives; the water pump, alternator, three rollers, power steering pump and the AC.
as for my car, I took the access plate behind the seats off and started the car to see/hear the problem.
once I removed the belt and try to wiggle the alternator pulley, it was obvious that the one way clutch was not working.
I also spun the rollers (3 of them ) to see/hear if the bearing was dry. good for me that the rollers were good. (they cost 2X the alternator pulley. I had local Porsche dealer do the water pump few months earlier so I knew that was OK. but checked it for play anyways.
spun the power steering and the AC pulleys as well as wiggle them for any play. all OK.

I got the pulley from Pelican Parts (45$) and the pulley tool from ebay for 17$
little bit of penetrating oil did the trick.
there's also YouTube on the pulley. it appears that most of the new cars have this. on one of the YouTube, it did mention that if the cap on the front of the pulley is missing, you may be in for a rough time trying to remove the pulley.