Chrysler 100, 115 and 140 HP Outboard Motors Service Manual, OB 3439, Page 174Get this manual
Subsection
_ GEAR HOUSING
GENERAL
The information in this section concerns the removalrepair and installation of the water pump, gear train and shift mechanism of the single piece gear housing they pass the outletAs they rotate and th volume (displacement) increases, the pressure dropsforming vacuum When the volume (displacement) is the greatest and th vacuum highestthe leading vane goes past the inlet and the vacuum draws cooling water into the body and carries it to the outlet where it is pumped through the motor cooling systemFigure 1
WATER PUMP
DescriptionThe water pump is located on top of the gear housingAn impeller inside the pump body is attached to the driveshaft and is propelled directly by the engineThe center of the pump housing is offset, causing the impeller vanes to flex as they rotate The impeller is sandwiched between the water pump body and water pump backplate creating sealAt low speedthe impeller vanes push tightly against the outside circumference of the pump body forming seal there as well The volume (displacement) between any two vanes is least as