1984-1986 Mercury Force 9.9 and 15HP Outboards Service Manual, Page 62Get this manual
SECTION
GEAR HOUSING AND WATER PUMP
GENERAL
This section deals with the removal, repair, and installation of the water pump, gear train, and shift mechanism of the gear housingThe volume (d isplacement) between any two vanes is least as they pass the outletAs they rotate and the volume (displacement) increases, pressure will drop, forming vacuum
WATER PUMP