1971 Johnson 4HP Outboard Motors Service Manual, Page 19Get this manual
CORE PLUGS If leakage occurs at core plug area, smart tap with hammer flat end punch in the center of the core plug wil1 normal1y correct this conditionSee Figure 3-10If necessary, remove core plug to clean out slow speed orifice holesSee Figures 3-11 and
If leakage persists, drill 1 inch hole through the center of the core plug to depth of not more 1 16 i.nch below its surfaceWith punchcarefully pry out the core plugSee Figure 3-11
Inspect clean the casting contact areaIf nlcks, scratches, or an out-ol-round condition exist, the casting will have to replacedIf casting opening is normal, apply bead of Sealer 1000 to the outer edge of new core plugPlace new core plug Flatten to tight fit with in casting, convex side flat end punch hammer, and check for leakageLEAD SHOTS