198
COOLING SYSTEM
OPERATION
OPERATION
Cylinder Block / Cylinder Head
Cooling
The thermostat is located in the top of the cylinder
head. A separate pressure valve is positioned in
the top of the cylinder block adjacent to the
exhaust cover. The thermostat and pressure valve
control the flow of water entering the vertical water
passages of the cylinder head.
The controlled discharge of water from the ther-
mostat and/or the pressure relief valve allows
water from the top of the cylinder block to enter
the cylinder head. Water flows down through the
cylinder head and exits at the bottom of the cylin-
der head. The water outlet of cylinder head aligns
with a water passage at the bottom of the cylinder
block. Circulated water flows through the outlet
passage of the block to the adapter/exhaust hous-
ing and then out of the outboard.
At low speed
, temperature is thermostatically
controlled. The spring loaded thermostat remains
on a seat in the cylinder head. Water flows
through the thermostat only when it is open. The
thermostat opens at approximately 143°F (60°C).
At higher speeds
, temperature is water pressure
controlled. The pressure relief valve spring ten-
sion provides the proper “blow off” pressure. The
valve lifts from the seat in the cylinder block at
approximately 2000 RPM. Cooling water flows
around the valve to achieve high speed cooling.
EMM
and Vapor Separator
Cooling
Cooling water is routed through the
EMM
water
cavity. Cooling of the
EMM
minimizes the temper-
atures of internal components.
Cooling water is routed to the water inlet fitting of
the vapor separator water cavity. Cooling the
vapor separator fuel chamber minimizes fuel
vaporization.
Cooling water from the
EMM
and vapor separator
exits through the overboard indicator. See
HOSE
ROUTING AND WATER FLOW DIAGRAM
on
p. 192.
IMPORTANT:
Improper
EMM
cooling will acti-
vate service codes (code 29 and 25) and initiate
S.A.F.E.
or SHUTDOWN. Refer to
EMM DIAG-
NOSTICS
on p. 93 for specific service code infor-
mation.
1.
Thermostat
2.
Pressure valve
002441
1 2
1.
Overboard indicator
002457
1
Summary of Contents for E-tec 75 HP
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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 ...
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