Hello all im new to the forum and appreciate your patience as I learn. I have 2003 c230k coupe with 70k miles on it I have an ongoing issue with the bolt for the belt tensioner shearing it has happened 3 times now none of the other pulleys feel difficultbto turn and I can't seem to figure out what is causing this. I have replaced the bolt witn a stronger class and had the same results despite this. Any suggestions would be greatly appreciated.