Today I was driving and I noticed a grinding sound. I also noticed my stock voltmeter was slightly bouncing(not sure if alternator is failing or something else is creating drag), however my digital voltmeter read pretty consistently between 14.0 - 14.5. I can't tell if it's my alternator or supercharger. I used a stethoscope and it didn't help. Car is holding boost correctly. Drives fine. [video]http://vid1214.photobucket.com/albums/cc483/stillboredb/Grind_zpsacmxzqzk.mp4[/video]
Is it actually a grinding sound in person? Sounds like a rattle on video. Have you tried the old screw driver trick? Place the screw driver on surfaces and put your ear against it.sometimes helps to pinpoint sound?
It is hard to describe the sound. It is intermittent but happens pretty consistently at idle. I used a stethascope on the supercharger and alternator, I couldn't differentiate them acoustically. But yes, it's the "rattle" near 7 seconds in.