Mercury Mariner 4, 5, and 6HP 4-Stroke Factory Service Manual, Page 166Get this manual
CYLINDER BLOCK AND CRANKCASE
7Assemble connecting rod to piston, secure with piston pin and new piston pin clips
NOTE: Make sure the connecting rod is orientated correctly for reassembling (3H6 mark must face the oil pan)NOTE: Reassemble the piston so that the arrow faces the camshaftNOTE: 45 hp has flat top piston6 hp has dome type piston6 hp will be marked on top of piston45 hp hp
4-Stroke Outboard Oil (92-828000A12)
dPiston Pin Clip (2)Direction Arrow (Must Face The Camshaft)Piston Pin Clips Should Bridge the Notch in the Piston Second Piston Ring Piston