1984-1986 Mercury Force 4HP Outboards Service Manual, Page 57Get this manual
SECTION
GEAR HOUSING
GENERAL
The information in this section covers removal, repair and installation of the water pumpgear train and shift mechanism of the gear housingWhen the volume (displacement) is the greatest and the vacuum the highestthe leading vane goes past the inlet, the vacuum will draw cooling water into the body and carry it to the outlet where it is pumped through the motor cooling systemFigure 1At low speeds, the pump isdisplacement pump; as motor speed increaseswater resistance causes the vanes to flex in and it becomes centrifugal pump
WATER PUMP
DescriptionThe water pump is located on top of the gear housingAn impeller inside the pump body is attached to the driveshatt and is propelled directly by the engine