Mercury - Water Pump Impeller Cooling System Component Flexible Marine Elastomer 89981. Overview. There's something timeless about running an older Mercury two-stroke. Those light, dependable 3.9-9.8 horsepower outboards have powered fishing trips, camping weekends, and quiet shoreline cruises for generations. But even the toughest vintage motor relies on one small part to stay cool and keep running strong - the water pump impeller. The Quicksilver 89981 Water Pump Impeller brings fresh reliabil