Johnson Pump I09-1026B-1 F4 Impeller (MC97)

The Johnson Pump I09-1026B-1 F4 Impeller (MC97) is an essential cooling system component designed for marine and automotive engine maintenance. This impeller serves as the circulatory pump of your engine's cooling system, continuously forcing coolant through passages to dissipate heat and maintain optimal operating temperature. Whether you're running a high-performance build, restoring classic marine equipment, or maintaining standard fleet vehicles, this OEM-spec replacement impeller is critical to preventing catastrophic overheating and engine seizure.

The F4 impeller design uses precisely engineered rubber or elastomer vanes that flex and expand as the rotor spins, creating dynamic pressure differentials that push coolant at consistent flow rates throughout the engine block. Over time, these vanes degrade from constant thermal cycling, saltwater corrosion (especially in marine applications), and friction—resulting in reduced flow, cavitation noise, and eventual seal failure. The MC97 designation indicates compatibility with specific Johnson Pump housings and engine configurations. This compact unit weighs just 0.3 lbs and fits within tight engine compartments, making it a straightforward swap-out maintenance item that requires no modification to existing cooling loops.

Mechanics and vehicle enthusiasts should replace the Johnson Pump I09-1026B-1 F4 Impeller annually—especially before peak season use or after extended storage—to ensure reliable heat rejection and eliminate the risk of mid-season failure. This is particularly important for high-RPM applications, freshwater cooling systems, and any engine running elevated coolant temperatures. Verify your specific engine model and Johnson Pump housing type against the MC97 reference to confirm fitment before purchase. This genuine OEM-grade replacement impeller is available for sale and comes with specifications that meet original equipment standards for durability and flow rate.