Adapter/Inner Exhaust Housing; Pressure Relief Valve; Thermostats; Block Venting - BRP Evinrude E-Tec Series Service Manual

Adapter/Inner Exhaust Housing

Adapts the cylinder/crankcase assembly (pow-
•
erhead) to the exhaust housing and the water
tube.
Provides water passages which route incoming
•
and outgoing cooling water.
Provides exhaust passages which connect to
•
the lower inner exhaust.
1
20 in. models
2
25 in. models
1. Adapter/inner exhaust housing
2. Water tube(s)

Pressure Relief Valve

A pressure relief valve is used to control water
flow and operating temperature at higher speeds
(above approximately 2500 RPM / 21 PSI). Pres-
sure relief valve activates or "blows-off the seat"
as water pressure increases. Spring tension is
used to set the "blow off" pressure.
Overheating: A restricted or faulty valve typically
results in HIGH SPEED overheating. (Minimum
water pressure at 3000 RPM is 21 PSI.)
25 in. models
005396
Overcooling: Debris may prevent the valve from
closing completely.
Pressure Relief Valve Components

Thermostats

Thermostats are used to control water flow and
operating temperature at lower speeds (below
2500 RPM).
Overheating: Restricted or faulty thermostats typ-
ically result in LOW SPEED overheating.
Overcooling: Debris may prevent the thermostat
from closing completely.
Thermostat
Refer to THERMOSTAT SERVICING on p. 233.

Block Venting

A fitting and hose from the top of the block allows
the constant movement of water and/or air from
the center water passage (top) of the block. Circu-
lated water flows through the EMM to the Vapor
Seperator and then overboard through the water
outlet fitting in the rear exhaust grommet.
COOLING SYSTEM
COMPONENTS
005391
005392
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