Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 137Get this manual

Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 137

Cylinder Head 1Inspect the cylinder head for mineral depositS corrosion in the water passage waysclean any depositscorrosion observed2Inspect the cylinder head for carbon deposits In combustion chamber (use round scraper to clean away deposits)Be careful not to scratch or remove material
VALVE GUIDE INSPECTION
1Measure the valve guide bore (a)If valve guide wear is out of specification, replace the valve guide

Valve Guide Inside Diameter

Intake Valve Exhaust Valve

0.21650.2170 in(5.5005.512 mm)

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