Mercury - Impeller for 3.4L Carbureted Two Stroke Outboards Cooling System Component Flexible Marine Polymer 85647. OverviewIf you've spent enough weekends on the water, you know there are certain parts you never take for granted. An engine can sound strong, feel powerful, and look clean-but none of that matters if it can't stay cool. That's why the Mercury Marine part number 85647 Impeller gives boaters such peace of mind. It's one of those quiet, behind-the-scenes components that keeps your tr