Mercury Mariner 4 and 5HP 4-Stroke Outboards Service Shop Manual 1999, Page 157Get this manual
CYLINDER BLOCK AND CRANKCASE
ACAUTION
Eye protection must be worn while installing piston ringsIMPORTANT: 00 Not mistake the top and second piston ringsThe rings are different and must be installed in correct orderNOTE: The piston ring end gaps must be staggered as shown to avoid the direction on the piston pin
8Install the oi ring as follows: aSet the oil ring expander in the oil ring groovePosition the ring ends with the 1200 location as shownMatch the ring ends correctly as shown in Figurel bWhile holding down the oil ring ends by thumb, install the upper side railPosition the end gap at 1316 in(20 mm) to the leh 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 su re the rotation of the piston rings are smooth11 Position the piston end gaps at the positions shown