Mercury Mariner 8/9.9HP 4-Stroke Factory Service Manual, Page 129Get this manual
Valve Guides NOTE: Inspect the valve guides for weardamageIf valve guide wear is out of specifications, replace the valve guideMeasure valve guide bore
3Install the new valve guide and circlip using valve guide installer bushing along with the valve guide remover
aValve Guide Remover (91-809495A1)Valve Guide Installer Bushing (91-809496A1)
Valve Guide Bore Specifications Intake Valve Exhaust Valve 0.21650.2170 in(5.500 5.512 (5 500512 mm) )
4After installing the valve guide, ream the valve guide using valve guide reamer to obtain proper stem-to-guide clearance