We have replaced a number of A.I.R. pumps on 103 motors. It is strange as I don't think we have ever replaced one on a 380 which has a similar pump and would be much older. The bearing is always what fails. I would have to assume that the belt puts more of a load on the 103 pump. Then again the 380 can have its belt removed where as the 103 can't so maybe there have been some 116 failures that I didn't notice.
Bosch Master, ASE Master, L1
33 years MB technician