1972 Johnson 4HP Outboard Motor Service Manual, Page 19Get this manual
CORE PLUGS If 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
If leakage persists, drill 1 inch hole through the center of the core plug to depth of not more than 116 inch below its surfaceWith punchcarefully pry out the core plugSee Figure 3-11
Inspect and clean the casting contact If nlcks, scratches, or an out-of-round condition exist, the casting will have to replacedIf casting opening is normal, apply bead of Sealer 1000 to the auter edge af new core plugPlace new core plug in casting, convex side Flatten to tight fit with flat end punch and hammer, and check far leakageLEAD SHOTS