Impeller Johnson/Evinrude 4-7 HP – Key to Cooling Small Outboards

The Johnson/Evinrude 4-7 HP impeller is an essential component for the proper operation of the smallest outboard engines. This impeller fits 2-stroke Johnson/Evinrude models ranging from 4 to 7.5 HP (including popular 4, 5, 5.5, and 6 HP engines from the 1960s and 1970s), as well as certain 4-6 HP 4-stroke models with the US-designed lower unit. By replacing the original OEM part numbers 389576 and 436137, the impeller ensures that the water pump regains its full cooling capacity.

With 6 blades made from high-quality flexible material, this impeller provides continuous cooling water flow even within the tiny water pumps of small motors. The included new gasket facilitates correct installation and sealing, preventing water leaks or air suction that could impair pump performance. Small outboards often run at high RPMs to propel a boat or at prolonged idle (trolling) – in both cases, adequate cooling is critical. Installing this impeller guarantees your engine won’t overheat, thereby protecting key components like pistons and cylinder heads from heat damage. Replacing it regularly (annually or at signs of wear) will ensure trouble-free engine operation every time you hit the water.

• For Tenders and Dinghies: This impeller is intended for the tiniest boats – inflatable tenders, motorized canoes, small jon boats – where 4-7 HP engines are used and reliable cooling is needed in a compact setup
• Restore Performance: Even little engines need full performance – after replacing the impeller, you’ll notice a steady tell-tale stream and a cooler running engine, indicating your pump is working as it should
• Marine-Grade Build: The material used is meant for the marine environment – the impeller remains flexible in cold conditions (early spring/late fall) and does not deform in hot weather
• Installation: Replacement is simple: remove the water pump cover, swap out the old impeller (don’t forget the woodruff key), use the new gasket provided, and reassemble. The result is a water pump that functions like new
• On-Water Assurance: With a healthy impeller, your small Johnson/Evinrude engine will start easier and run at correct temperature, giving you confidence and enjoyment during short trips or as an auxiliary to your main engine