My 2006 CLK350 has been eating the serpentine belt. I've replaced all the pulleys, tensioner and the Crankshaft harmonic damper (which was bad). The belt isn't breaking from something ceasing up, rather its being thrown off the tracks somehow and getting chewed up in the upper pulley. I'm at a loss..i even put straight edges across all the pulleys to check alignment....Anyone see this before?

Thanks

 

The only time I've had a problem like that was a cracked pulley.