180
COOLING SYSTEM
COMPONENTS
COMPONENTS
Water Pump and Intakes
External water intakes mounted in the gearcase
housing collect water and must supply the inlet
side of the water pump with an unrestricted and
unaerated water supply. Water is drawn into the
water pump through a hole in the lower plate of
the water pump assembly. All cooling water to the
powerhead is provided by the water pump.
• A nylon wedge (impeller key) is used to engage
the impeller bushing and driveshaft.
• The nylon impeller housing with liner must seal
against a separate water pump plate.
• The bottom plate MUST seal to gearcase.
• The pump operates as a positive displacement
pump at LOW speeds (below 1500 RPM) and
as a centrifugal pump at HIGHER speeds.
Refer to WATER PUMP SERVICE on p. 294, or
WATER PUMP SERVICE on p. 316 for servicing.
IMPORTANT: The water pump housing on 2-
cylinder models includes a small hole to the rear
of the water outlet. This hole provides cooling
water for the tip of the exhaust passage. Be sure
to use the correct parts when replacing the water
pump.
Exhaust Housing
2-CYLINDER MODELS
The water pump outlet connects with passages
located in the outboard’s midsection. A grommet
seals the water pump housing to the exhaust
housing.
Water supplied to the exhaust housing provides all
cooling water to the cylinder block.
Water Supply Tube
3-CYLINDER MODELS
The water pump outlet connects with the water
supply tube located in the outboard’s midsection.
Grommets seal the water tube to the water pump
housing and the adaptor housing. The water tube
fastens to the base of the adapter housing with a
retainer plate and screws.
Water supplied to the water tube provides all cool-
ing water to the adapter housing and cylinder
block.
1. Water inlet
2. Water outlet
3. Seal
4. Plate
001216
001217
1. Hole 004970
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