Mercury Mariner 8/9.9HP 4-Stroke Factory Service Manual, Page 20Get this manual
Propeller Replacement Removal WARNING
If the propeller shaft is rotated while the engine is in gear, there is the possibility that the engine will crank over and startTo prevent this type of accidental engine starting and possible serious injury caused from being struck by rotating propeller, always shift outboard to neutral position and remove spark plug leads when you are servicing the propeller1Shift the outboard to neutral position2Remove the spark plug leads to prevent engine from starting3Place block of wood between gear case and propeller to hold propeller and remove propeller nut
Installation
1Coat the propeller shaft with Quicksilver AntiCorrosion GreaseIMPORTANT: To prevent the propeller hub from corroding and seizing to the propeller shaft, especially in salt water, always apply coat of Quicksilver Anti-Corrosion Grease to the entire shaft at the recommended maintenance intervals and also each time the propeller is removed