This happened to the other day. While on my way to work i was pulling into town after 45 miles of interstate hwy driving and i hear this strange sound. Similar to a belt slipping sound that i have heard many times before but not exactly the same. I take a turn and i hear the sound. I rev it up a bit and i hear the sound. Very strange, but being just like a quarter mile from my destination i eased on. I get to work, pop the hood and find that the accessory drive belt is just kinda flooop flooop floop ing around.
Upon further inspection i find this
I guess the bottom half of that is out on the highway somewhere. Fortunately i was able to grab a replacement off of the 190D parts car.
The belt now feels tighter than it ever did before and I think the engine temperature now stays a bit lower during high load diving.