1995 Mariner Mercury Outboards Service Manual 50HP 4-Stroke, Page 152Get this manual
Crankshaft 1Thoroughly clean crankshaft and inspect bearing surfacesReplace crankshaft if bearing surfaces are pittedscoredor discolored2Measure Run-outReplace crankshaft if out of specification
5Place piece of plastigauge onto each crankshaft bearing surface
aPlastigauge
Crankshaft Run-oul
6Install crankcase coverApply oil to the cover bolts and torque cover bolts in sequence and in two steps
Checking Main Bearing Clearance
IMPORTANT: Do not interchange the main bearingsReinstalled in their original position1Clean all the old sealing material from the split line on the crankcase cover and cylinder block