1979 Evinrude 4 HP Outboards Service Manual, PN 5424, Page 25Get this manual
bIf leakage persists, drill 18 inch (3 .2 mm) hole through the center of the core plug to depth of not more than 116 inch (2 mm) below its surfaceWith punch, carefully pry out the core plug See Figure 3-14cI nspect and clean the casting contact area If nicks, scratchesor an out-of-round condition exist, the casting will have to be replacedIf casting opening is normalapply bead of OMC AdhesiveM" to the outer edge of new core plug Place new core plug in castingconvex side upFlatten to tight fit with flat end punch and hammer, and check for leakageLEAD SHOTS If leakage occurs at lead shot area, follow these corrective measures: aIf leakage is slightsmart tap with hammer in the center of the lead shot will normally correct this condition See Figure 3-15 Figure 3-16Removing Lead Shot
FUEL TANK aInspect the filler cap and gasket for wear, damage, or leakage; replace if necessarybRemove shut-off valveRemove gum and varnish deposits by washing in OMC Engine CleanerApply drop of OMC part number 200763 Gasoila to threads at shut-off valve on installation to fuel tankcInspect the fuel tank for leakageIf leakage occurs, replace tankdFlush tank with clear gasoline or solvent at least once year