Mercury - Water Pump Kit Cooling System Marine Composite & Rubber 8M0137849. Overview. There's a certain rhythm to a good day on the water-smooth throttle response, a steady hum from the outboard, and the comforting feeling that everything beneath your feet is running exactly as it should. A dependable cooling system is a huge part of that peace of mind. The Mercury 8M0137849 Water Pump Kit is one of those quiet heroes you rarely think about until you need it. Once installed, you can feel the di