N_Rob

Hey guys, the other day I started hearing something that sounded like pulley noise that was rpm dependent. I replaced the idler pulley 3k miles ago so I assumed it wasn't that. I removed the sc belt and hand spun the idler, tensioner, and supercharger pulley. The tensioner and supercharger pullies made some noise but the tensioner was certainly louder. I drove the car around my neighborhood with the sc belt off and still heard the sound, just much fainter this time. To me at least, this points to the sc bearing since it is spinning regardless of whether the belt is on or not and the tensioner doesn't spin while the belt is off, but the tensioner is making an unnerving sound too. I'm going to include a video of me hand spinning the pullies, let me know what you guys think. (Yes I know the sc clutch surface is scratched, it wasn't me I promise haha I've only had the car 7k miles)

w204_racing

bbirdwell

How many miles on the car? Info like this helps to make a diagnosis. Possibly bad supercharger rear bearings (lots of work but do-able). Pull both belts and rotate all pulleys by hand and listen for noise and feel for roughness. Need more info to assist you.

N_Rob

Miles are high, 184k. I knew about the rear supercharger bearings so I manually twisted the supercharger pulley while keeping my ear near the throttle body and couldn't hear anything from the back. That probably doesn't mean much I know. I'll pull the serpentine belt off when I can, I'll be a little busy until Thursday or so and that's probably when I'll get to it. I'm not driving the car in the meantime of course, I don't want to take the chance if it's a bad bearing. I've seen the stories on this forum when they fail in motion.