Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 160Get this manual
Crankshaft 1Thoroughly clean crankshaft and inspect bearing surfacesReplace crankshaft if bearing surfaces are pitted, scored, or discolored
5Place piece of plastigauge onto each crankshaft bearing surface
2Measure Run-outReplace crankshaft if out of specification53812
Install crankcase coverApply oil to the cover bolts and torque cover bolts in sequence and in two steps
Crankshaft Run-out 0.0012 in(0.03 mm) 3Clean oil holes in crank rods and block
Checking Main Bearing Clearance