195
COOLING SYSTEM
COMPONENTS
9
COMPONENTS
General Description
All models use a two-stage cooling system
design. The cooling system is dependent on water
pump pressure and controlled by thermostat and
pressure relief valve operation.
IMPORTANT:
Restricted or inadequate water
flow through the outboard reduces cooling system
performance and may lead to severe powerhead
damage.
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 stainless steel
liner must seal against a separate stainless
steel water pump plate.
•
The pump operates as a positive displacement
pump at LOW speeds (below 1500 RPM) and
as a centrifugal pump at HIGHER speeds.
•
The bottom plate MUST seal to gearcase hous-
ing.
Refer to
WATER PUMP
on p. 262
for water pump
servicing.
Water Supply Tube
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.
(Impeller key removed for clarity)
1.
Water inlet
2.
Water outlet
3.
Seal
4.
Plate
5.
O-ring
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DSC02328
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Summary of Contents for E-tec 75 HP
Page 1: ......
Page 233: ...233 POWERHEAD POWERHEAD VIEWS 10 POWERHEAD VIEWS Port Short Block Starboard Short Block ...
Page 234: ...234 POWERHEAD POWERHEAD VIEWS Port Dressed Powerhead Starboard Dressed Powerhead ...
Page 235: ...235 POWERHEAD POWERHEAD VIEWS 10 Front ...
Page 236: ...236 POWERHEAD POWERHEAD VIEWS Rear ...
Page 237: ...237 POWERHEAD POWERHEAD VIEWS 10 Top ...
Page 298: ...S 2 ...
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