1979 Johnson Outboards 4 HP Models Service Repair Manual P/N JM-7903, Page 25Get this manual
Quality of the image is intentionally reduced!
If leakage persists, drill 18 inch (3.2hole through the center of the plug to depth of not than 116 inch (2below its surfaceWith punch, carefully out the plugSee Figure 3-14 Inspect and clean the cast