2001 Mercury Mariner 50-60HP Factory Service Manual, Page 268Get this manual
CYLINDER BLOCKCRANKCASE
4Remove the connecting rod capMeasure the compressed plastigauge to check the connecting rod oil clearanceReplace bearings if oil clearance is not in specification
Connecting Rod Oil Clearance 0.0008 0.0020 in(0.0200.052 mm)
Thermostat
1Measure the lift of the thermostat at the operating water temperature listed