Mercury - Water Pump Repair Kit Cooling System Service Multi-Piece OEM Kit 89983Q1. Overview. When you rely on a mid-range Mercury or Mariner outboard, you learn quickly that cooling performance isn't something you gamble with. These engines work hard pushing fishing rigs, river boats, pontoons, and jet-drive setups through skinny water and shifting currents. Over time, silt, sand, and debris grind away at the water pump's internal parts. Before you know it, the telltale weakens, temperatures cr