2001 Mercury Mariner 50-60HP Factory Service Manual, Page 270Get this manual
CYLINDER BLOCKCRANKCASE
Main Bearing Installation
IMPORTANT: Do not interchange used main bearingsReinstall in their original position1Check clearance of each bearing, following procedure in Cleaning and Inspection2Clean all the oil from the main bearing surfaces on the cylinder block and crankcase cover3Install main bearingsMake sure the locking tab on each bearing fits into its notch in the cylinder block