You are safe in most cases with the valve job on this engine. It is likely that it did burn an exhaust valve on that cylinder if a valve adjustment wasn't done on time at one time or another. I'd do the valve job and hope for the best.

------------------
Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM