Mercury Mariner 8/9.9HP 4-Stroke Factory Service Manual, Page 128Get this manual
Camshaft 1Inspect the camshaft for any of the following conditionsIf not within specification, or excessive wear, replace the camshaft Cam Lobe Length Cam Lobe Width Heat Discoloration Pitting Scratching
Cylinder Head
1Inspect the cylinder head for the following conditions: Mineral DepositsCorrosion in Water Passage Ways Carbon Deposits In Combustion Chamber (use round scraper to clean away deposits)Be careful not to scratch or remove material
2Inspect cylinder head for warpageIf not within specification, replace cylinder head