Mercury - Water Pump Assembly MerCruiser Cooling System Marine Aluminum Housing 8M0113736. Overview. When you've spent enough time on the water, you learn to trust the parts that keep your engine cool and calm, even when the day heats up. A dependable water pump becomes one of those unsung heroes - working quietly beneath the deck so you can enjoy the ride without worrying about temperature spikes or unexpected shutdowns. The Mercury 8M0113736 Water Pump Assembly is exactly that kind of part. It