1980 Johnson 4HP Service Manual, Page 67Get this manual
REMOVAL OF GEARCASE It is possibIe to remove the gearcase without removing the powerhead exhaust housingRemove the screws attaching the gearcase to the exhaust housingSee Figure 6-3Withdraw the gearcase carefully to avoid damaging the driveshaft and water tube
Remove plate from impeller housing coverRemove impeller from impeller housing cupmove spacer from inside of water pump cavitySee Figures 6-7 and 6-12Remove and discard water tube grommet from impeller housing coverSee Figures 6-4 and 6-7Inspect components for wear and deterioration, and replace as necessaryReassembIe impeller into cup with bIades positioned as shown in Figure 6-6