393630 Water Pump Impeller Repair Kit with Housing for 2-Stroke(20,25,30,35 Hp) Outboard Engines Replace 393630, 0393630, Sierra 18-3382Model: 393630About this item Applications: 2-Stroke 20 & 25 HP (1985 - 2005) 25 HP Commercial (1998 - 2001) 30 HP and 35 HP (1980 - 1982) 30 HP and 35 HP (2 Cylinder) (1983 - 2005) OE: 393630 393509 391636 0393630 Sierra: 18-3382 Advice: Check your water pump impeller every season and replace it every two to three seasons to ensure that the engine runs smoothly. The water pump impeller is designed to push coolant through the engine block, radiator, and hoses to effectively transfer heat away from the system. Size: 3.94 x 3.94 x 2.76 inches.