Mercury - Water Inlet Port Screen Cooling System Component Stainless Mesh 41133. Overview. Keeping your outboard cool starts with steady, clean water flow. The Mercury Marine 41133 Water Inlet Port Screen is built for Mercury 8-25HP carbureted FourStroke engines, protecting your cooling system by filtering out sand, weeds, and debris before they can cause problems. Its stainless mesh screen sits securely in the water intake, keeping your impeller safe and your cooling passages clear. It's a simp