Mercury - Water Pump Repair Kit, 3.3HP Cooling System 8M0080264. Overview. These little 3.3HP Mercury and Mariner outboards are simple motors, but they don't give you much warning when the water pump starts getting tired. A weak pee stream, the engine running warmer than it should, or a bit of steam at idle usually means the impeller isn't moving water the way it used to. This kit gives you everything to rebuild the pump the right way-impeller, gaskets, o-ring, plates, the key, and the hardware