Engine valve spring, retainer, collet, and stem seal components with identification diagram and replacement procedure for smart 450/451/452/454.

Exploded diagram of valve spring assembly and three-step valve stem seal replacement photos with numbered callouts.

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See all Powertrain figures for the Fortwo (450), or browse the full figure library. Part numbers and callouts are community-sourced and cross-referenced against the manuals — confirm with your VIN before ordering.