Evinrude & Johnson E75DPLSCB, Service Manual, Page: 194 / 349

192
COOLING SYSTEM
COMPONENTS
Pressure Relief Valve
A pressure relief valve is used to control water
flow and operating temperature at higher speeds
(above approximately 2000 RPM). The pressure
relief valve opens as water pressure increases.
Spring tension sets the opening pressure.
Overheating:
A restricted or faulty 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 2000 RPM).
Overheating:
A restricted or faulty thermostat typ-
ically results in LOW SPEED overheating.
Overcooling:
Debris may prevent the thermostat
from closing completely.
Block Venting
A fitting and hose connected to the top of the
exhaust cover allows the constant movement of
water and/or air from the block. Circulated water
flows through the
EMM and vapor separator
before exiting through the overboard indicator.
Water Pressure Connection
A fitting and hose for an accessory water pressure
gauge can be connected at the top of the cylinder
block next to the pressure valve housing.
Pressure relief valve components
002437
1. Cover and O-ring
2. Spring and thermostat
3. Seal
4. Cylinder head
002439
4 3 2 1
1. Fitting 002440
1. Fitting 002461
1
1