Mercury Mariner 4, 5, and 6HP 4-Stroke Factory Service Manual, Page 167Get this manual
CYLINDER BLOCK AND CRANKCASE
CAUTION
Eye protection must be worn while installing piston ringsIMPORTANT: Do Not mistake the top and second piston ringsThe rings are different and must be installed in correct order
NOTE: The piston ring end gaps must be staggered as shown to avoid alignment with the piston pin8Install the oil ring as follows: aSet the oil ring expander in the oil ring groovePosition the ring ends with the 120 location as shownMatch the ring ends correctly as shown in Figure1bWhile holding down the oil ring ends by thumb, install the upper side railPosition the end gap at 1316 in(20 mm) to the left of the oil ring endscAs in the same manner as the above step b, install the lower side railPosition the end gap at 1316 in(20 mm) to the right of the oil ring ends9Install the top and second ring in the correct orderInstall the piston rings with the marking side facing up10Make sure the rotation of the piston rings are smooth11Position the piston end gaps at the positions shown