Evinrude E-Tec 40 HP, Service Manual

Page: 179 / 426

177
COOLING SYSTEM
COMPONENTS
9
Adapter/Inner Exhaust Housing
3-C
YLINDER
M
ODELS
•
Adapts the cylin der/crankcase assembly (pow-
erhead) to the exh aust housing and the water
tube.
•
Provides water passages which route incoming
and outgoing cooling water.
•
Provides exhaust p assages which connect to
the gearcase.
Pressure Relief Valve
A pressure relief valve is used to control wa ter
flow and operating temperature at highe r speeds
(above appro ximately 1800 RPM). The pressure
relief valve ope ns a s water pressure incre ases.
Spring tension sets the opening pressure.
Overheating:
A restricted or fa ulty valve typically
results in HIGH SPEED overheating.
Overcooling:
Debris may prevent the valve from
closing completely.
Thermostat
The thermostat controls water flow and operating
temperature at lower speeds (below 1800 RPM).
Overheating:
A restricted or faulty thermostat typ-
ically results in LOW SPEED overheating.
Overcooling:
Debris may prevent the thermostat
from closing completely.
1. Megaphone
2. Exhaust housing
3. Water tube
4. Adapter housing
5. Inner exhaust housing
002436
3
5
2
4
1
Pressure relief valve components
002437
1. Cover and O-ring
2. Spring and thermostat
3. Cylinder head
4. Cylinder head seal
002439
4 3 2 1