Mercury Mariner 4, 5, and 6HP 4-Stroke Factory Service Manual, Page 130Get this manual
CYLINDER HEAD
Cylinder Head Reassembly
IMPORTANT: Reassemble valve train components in their original location1Install valves, lower seats, springs,spring retainers and keepers
NOTE: Compress valve springs using suitable box end wrench
4-Stroke Outboard Oil (92-828000A12)