176
COOLING SYSTEM
COMPONENTS
COMPONENTS
Water Pump and Intakes
External water int akes mo unted in t he ge arcase
housing collect water a nd must su pply the inlet
side of the wa ter pu mp with a n un restricted an d
unaerated water su pply. W ater is drawn into the
water pump throu gh a h ole in th e 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 lin er must seal
against a separate water pump plate.
• The bottom plate MUST seal to gearcase.
• The pump opera tes as a p ositive displacement
pump at LOW speed s (below 1500 RPM) and
as a centrifugal pump at HIGHER speeds.
Refer to WATER PUMP SERVICE o n p. 298, or
WATER PUMP SERVICE on p. 320 for servicing.
IMPORTANT: The water pump hou sing on 2-
cylinder models includes a small hole to the rear
of the wa ter 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 p ump outlet connect s wit h p assages
located in th e o utboard’s midsection. A gro mmet
seals th e wate r pu mp 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 wa ter pump outlet co nnects with the wa ter
supply tube located in th e outboard’s midsection.
Grommets seal the water tube to the water pump
housing and the adaptor housing. The water tube
fastens to the ba se of th e adapter housing wit h a
retainer plate and screws.
Water supplied to the water tube provides all cool-
ing water to the adap ter housing and cylind er
block.
1. Water inlet
2. Water outlet
3. Seal
4. Plate
001216
001217
1. Hole 004970
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