A grinding noise has gotten to be pretty loud on my 2009 Scion TC with 135K miles. It has zero issues running. Took it to the mechanic and he said he was 90% sure it was the alternator so I went ahead and replaced it. I then found out that was not issue since the noise still persists. Anybody have any idea what else this could be or has anyone ever experienced this sound before? Please see the video below. Thank you!