I started up my Excursion Yesterday afternoon and it started making this rattle/knocking noise from the right side of the engine right away. I drove it the night before and it made no noise. I don't have any loss of power and im kinda stumped on whats making the noise

 

How is the oil level? Possibly a pulley bearing as well.

 

Oil level is fine just changed it two a little while ago. im starting to think its a pulley bearing as well but im not to sure.

 

Remove the serpentine belt and spin the tensioner pulley and the idler to start.

 

Turns out the tensioner pulley went bad got it fixed today

 

Was that all needed? Did you change the belt as well? If not may be a good idea. I would order it and a Idler now to be on the safe side.