Hello, I'm Danny.
It sounds like a bearing in the alternator or if equipped -idler pulley is going out. What I would suggest is with the engine running, Use a can of WD40 with the red small straw and individually spray behind the pulleys until you here the noise quiet for a few seconds to locate what components bearing is failing. After you do this get back to us after locating and we will provide you with the necessary repair guides. Hope this helps and thanks for using 2CarPros.
Saturday, April 17th, 2021 AT 6:50 PM