Mercury Mariner 8/9.9HP 4-Stroke Factory Service Manual, Page 14Get this manual
Inspection And Maintenance Schedule Conduct periodic, systematic inspection to uncover and correct failure before it can cause injury, inconvenience or mechanical damage
11Check tightness of bolts, nuts, and other fasteners
Every 300 Hours of Use or Three Years
1Replace water pump impeller (more often if overheating occurs or reduced water pressure is noted)2Replace oil filter3Replace thermostat
Before Each Use
1Check engine oil level2Check that lanyard stop switch stops the engine3Visually inspect the fuel system for deterioration or leaks4Check outboard for tightness on transom5Check steering system for binding or loose components6Remote Control Models Visually check steering link rod fasteners for proper tightness7Check propeller blades for damage
Before Periods of Storage