Water Pump Impeller Kit – Fits Mercury Marine 25-50 HP, Force 40-50 HP (Replaces 821354A2, 821354A1, 821354A04, 18-4531) 5.5HP followed by the upper (vent)

followed by the upper (vent) screw to allow air to enter

and check for any exhaust or water leaks

Is this thermostat for raw water or freshwater cooling systems

Place a new gasket (sold separately) on the housing and reinstall the cover

According to US Coast Guard regulations

Water Pump Impeller Kit – Fits Mercury Marine 25-50 HP, Force 40-50 HP (Replaces 821354A2, 821354A1, 821354A04, 18-4531) 5.5HP followed by the upper (vent)Product Details This Water Pump Impeller Kit Fits Mercury Marine 25 50 HP (Replaces 821354A2, 821354A1) provides all the necessary components for a complete water pump overhaul. It is designed for Mercury Marine 25 50 HP 4 Stroke outboards from 1998 and newer, including 25, 30, 40, 45, and 50 HP models. It also fits select Force 40 50 HP engines from 19951997. This kit serves as a direct replacement for Mercury Quicksilver part numbers 821354A1,