Mercury - Water Pump Pulley Serpentine Belt Cooling System Component Steel, Corrosion-Resistant Finish 8M0153706. Overview. Anyone who spends real time on the water knows how much trust you place in your engine's cooling system. When the sun is beating down, the chop picks up, and you're pushing through long stretches, you want to know that your engine is staying cool and steady without you giving it a second thought. That's where dependable parts really earn their keep. The Mercury Marine part