If no oil is to be seen then maybe the belt and pulleys are out of alignment, the crank pulley is coming apart and moving forward, the tensioner is too weak or the belt is too long.
True enough, and thanks.
However, I have had the serpentine come off my GMC due to a faulty PS pump.
As to the pulley alignment, with the fan assembly out, you can use a long straight edge on the crank pulley and see how close to alignment the other pulleys are.