2001 Mercury Mariner 50-60HP Factory Service Manual, Page 226Get this manual
CYLINDER HEAD
Valve Guide Replacement
1Heat the cylinder head in an oven to 390 (200 C)This will help to ease guide removal and installation and to maintain correct interference fit2Remove the valve guide using valve guide remover
aValve Guide Remover (91-809495A1) 3Install the new valve guide and circlip using valve guide installer bushing along with the valve guide remover