1976 Johnson 4HP 4R76, 4W76 Outboards Service Manual, Page 20Get this manual
CORE PLUGS aIf leakage occurs at core plug area; smart tap with hammer and flat end punch in the center of the core plug will normally correct this conditionSee Figure 3-10If necessary, remove core plug to clean out slow speed orifice holesSee Figures 3-11 and 3-1B bIf leakage persists, drillinch hole through the center of the core plug to depth of not more than 1 16 inch below its surfaceWith punchcarefully pry out the core plugSee Figure 3-11cInspect and clean the casting contact areaIf nicks, scratches, or an out-of-round condition exist, the casting will have to be replacedIf casting opening is normal, apply bead of OMC Adhesive "M" to the outer edge of new core plugPlace new core plug in casting, convex side upFlatten to tight fit with flat end punch and hammer, and check for leakage LEAD SHOTS