1980 Johnson 4HP Service Manual, Page 69Get this manual
WEEDLESS GEARCASE WATER PUMP Remove ring from top of driveshaft Remove two impeller housing screwsSee Figure 6-13While holding driveshaft down in gearcase, slide impeller housing and impeller off of driveshaftRemove key and slide impeller plate off of driveshaftRemove and discard water tube grommet from impeller housing dInspect necessaryand replace components as
Install impeller pin in driveshaftSlide impeller down driveshaft and engage impeller pinLubricate impeller with oil and install impeller housingRotate driveshaft in clockwise direction while slipping pump housing over impeller to position bIades correctlyAttach pump housing to gearcase with screws dipped in Gasket Sealing Compound and torque to specificationsfInstall new ring driveshaft