Operation; Cylinder Block / Cylinder Head Cooling; Vapor Separator And Emm Cooling - BRP Evinrude E-Tec Series Service Manual

COOLING SYSTEM

OPERATION

OPERATION
Cylinder Block / Cylinder Head
Cooling
The flow of water through the cylinder block and
cylinder heads is controlled by two thermostats
and one external pressure valve. The pressure
valve is connected by hoses to the top of the block
and each cylinder head.
1
1. Thermostats
2. Pressure valve assembly
The thermostats and pressure valve control the
flow of water entering the vertical water passages
of the cylinder heads.
Water outlet passage at the bottom of each cylin-
der head aligns with a water outlet passage in the
cylinder block. Water flows through the block to
the adapter housing and then out of the outboard.
At low speed, the pressure valve is against the
seat and the thermostats are closed. Warm water
from the top of the cylinder block gradually
migrates to the thermostat pocket at the top of
each cylinder head. Water movement is the result
of water "bleeding" past the pressure valve and
thermostats.
The thermostat eventually opens as the water
temperature in the system reaches 143°F (62°C).
When thermostat opens, increased water flow is
directed down the cylinder head water passage to
the water outlet passage of the block. Water then
exits through the adapter/exhaust housing.
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2 1
005393
At higher speeds, water pressure increases. The
pressure valve opens, or lifts off the seat, at
approximately 2500 RPM. Water flows through
the pressure valve and bypasses the thermostats.
Hoses route the water flow from the pressure
valve to the vertical water passages below the
thermostats. All water flows through the cylinder
heads to the outlet passages of the block and then
exits through the adapter housing.
This pressure controlled water outlet circuit pro-
vides a "high flow" discharge of water during high
speed operation.
This cooling system configuration provides "bal-
anced cooling" at higher RPM by utilizing one
pressure valve to control the discharge of water
through both cylinder heads.
Refer to HOSE ROUTING AND WATER FLOW
DIAGRAMS on p. 226.
Vapor Separator and
EMM Cooling
Cooling water is routed from the top of the cylinder
block to the inlet fitting of the EMM and through
the EMM water cavity. Cooling of the EMM mini-
mizes the temperatures of internal components.
Cooling water from the EMM is routed to the water
inlet fitting of the vapor separator water cavity.
Cooling the vapor separator fuel chamber mini-
mizes fuel vaporization.
Cooling water from the vapor separator is routed
to the water outlet fitting in the rear exhaust grom-
met.
Improper EMM cooling will acti-
IMPORTANT:
vate service codes (code 29 and 25) and initiate
S.A.F.E. or SHUTDOWN. Refer to EMM DIAG-
NOSTICS on p. 104 for specific service code
information.