Mercury Mariner 8/9.9HP 4-Stroke Factory Service Manual, Page 158Get this manual
Piston Rings and Connecting Rod 1Install the oil ring as shown
Piston Installation
IMPORTANT: Position the "UP" mark on the piston toward the flywheel side1Align ring end gap on the top and second piston rings with the locating pins in the ring groove
2Align ring end gap on the oil ring and oil ring side rails as shownaOil RingSide Ring (2)
2Install the second and top piston rings as shownAlign the end gaps with the locating pins in the ring groovesb UP b
aTop Piston RingSecond Piston RingOil Ring End GapOil Ring Side Rails End Gap
3Lubricate pistons, piston rings, and cylinder walls with oil
3Lubricate piston pin with oil and assemble the piston to the connecting rodAlways use new Circlipsa b