1995 Mariner Mercury Outboards Service Manual 50HP 4-Stroke, Page 153Get this manual
7Remove the crankcase coverMeasure the compressed plastigauge to check the main bearing clearanceReplace bearings if clearance is not in specification Checking Connecting Rod Bearing Clearance
IMPORTANT: Do not interchange used connecting rod bearingsReinstall bearings in their original position
1Clean all the oil from the connecting rod bearing surfaces and connecting rod journals on the crankshaft
NOTE: Refer to instructions in Cvlinder Block Reassemblv for selecting and installing connecting rod bearings53751
2Place piece of plastigauge on the connecting rod journals