The plastic timing chain guides on the M117 V8 are the community's number-one inspection point; owners urge changing the decades-old guides preventively to avoid grenading the engine, and note a quick valve-cover-off photo confirms condition. The 380's engine used a single-row chain that many upgraded to dual-row, while the 500/560 engines came from the factory with a dual-row chain.
M117 timing chain guides and single- vs dual-row chain
Mercedes-Benz SEC Coupe (C126) · mechanical