Believing your motor to be properly handled at the previous repair, I would suggest that what you are experiencing is normal and of no risk.

The risk to those motors comes from this normal activity occuring on old petrified chain rails which your newly worked motor hopefully doesn't have.

During the time in the early 70's when I worked at a MB dealer, we went after these ratlers for warrantee. After 30 years I can tell you that a good chain tentioner is extremely likely to have a rattle event occur, infrequently, but it will happen. Usually after sitting and especially after changing the oil.

There is a check ball valve inside the tentioner that keeps the oil pressure from the last running. A bit of dirt easily can cause it to lose the hydraulic effect.

If the rattle happens every time, you probably should replace the tentioner. Unless you paid to have it done in the last year I doubt there is any warrantee. If you took it apart and cleaned it, it would be good as new, anyway.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician