Owners flag the timing chain and its brittle plastic guides as an inspect-and-replace item on aging W116 V8s, well within reach of a home mechanic if done before failure. There is also a strong maintenance warning that lax oil changes on the M117 accelerate camshaft/OHC lobe wear, plus small preventive items like the plastic cam-lube oiler clips.
Timing chain, guides, and oil-change discipline
Mercedes-Benz S-Class (W116) · mechanical