Hello all hope you can please help, i was driving my 2005 Tribute on the highway and as i was getting off the highway i was hearing a rattling/loud clicking noise? I thought something was hitting the fan or worse case scenario a rode knock so i pull over to a parking lot to check on the motor noise,everytime i crank up i heard the noise, this time i popped the hood and asked my son to start the car while i look for obvious signs ,he started it made a louder noise then i seen the pulley i think it is to my left top of the side motor just break off and belt came loose? Im hoping that was causing the noise, is this common?

 

Here's a pic of the pulley, something broke on the side of it like something was attached to it then belt came off

 

And now noticed after the belt and that part broke off it doesnt make that rattling noise no more so im glade its not a rode knock, so its something related to the pulley or what ever that circle part is and the belt? Any help

 

So what can cause noise when the belt is on?