I started to have a whining noise coming from under the hood. After a little of trouble shooting I used the auto stethoscope to narrow down the issue to the idler bearing. Removing the belt is also good because it allows to spin the pulley freely thus making it possible to hear the idler bearing roaring
Here is how I removed the old bearing. First, remove the serpentine belt from the pulley only, so you know actually how it goes back on. Remove the bolt that holds on the pulley. You will need a snap ring plier to pull off the c-clip.
I used a socket only to remove the bearing. DO NOT USE the socket to reinstall, it will damage the bearing. Use the old bearing (line it up and tap it in)
You can buy this bearing at just about any auto parts store. Take the old bearing with you to the parts store and match it up.
Reinstall the new bearing, c-clip, mount the idler pulley (torq to 16 lbs) , serpentine belt and you are good to go.