Got a noise I'm hoping someone else has experienced and can tell me what it is. For about 6 months every time I start my 2006S (which has 140,000 miles) I hear what sounds like steel on steel scraping (like 2 pulleys against each other. After a couple minutes of warm up the noise goes away. Yesterday as I was pulling into a parking spot it began to make a very loud scraping and rattle sound. It was like either the pulley fell off it's spindle or a piece broke off and it is rattling around. Nothing else happened - no dash lights came on, it still runs fine, no leaks or smoke or smells (maybe a little smell of burning brakes a belt). Using my stethoscope the sound seems to be coming from inside the supercharger intake pipe. Ant Ideas what this could be?

 

Turns out my scrapping, rattling sound was a bad alternator.