As with all M116 / M117 engines, check for timing chain stretch and chain guide / tensior wear.
This forum is full of stories with owners experiencing bent valves, etc. due to a timing chain becoming so loose that it skips a link on the cam sprocket, or a loose chain slapping against a plastic chain guide, the plastic bits get caught in the sprocket, causing a valve to hit a piston or ruining a camshaft.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".