1978 Johnson 4HP outboards Service Manual, Page 74Get this manual
1"0" ring 2Driveshaft 3Screw (2) 4Impeller housing 5Impeller 6Water pump plate 7Water tube grommet 8Oil retainer 9Plug and washer 10Gearcase 11 Thrust bearing 12Propeller shaft assembly 13Oil retainer 14Bearing housing assembly 15Seal 16Pinion gear 17Rivet 18Exhaust cover 19Impeller pin