Mercury Mariner 30/40 4-Stroke Outboard Service Manual 1998, Page 246Get this manual
CYLINDER BLOC KC RANKCASE
6Install main bearing halves into the crankcaseNOTE: Align each bearing projection with the notch in the crankcase
aMain Bearing Halves-Crankcase (4)
bProjection in Bearing
cNotch in Crankcase
7 Install crankcase onto cylinder block
SApply oil to the cover bolts and torque cover bolts in sequence and in two stepsIMPORTANT: Do not move crankshaft until measurement has been completed