217
Cooling System
Operation
9
Overcooling: Debris may prevent the valve from
closing completely.
Thermostats
Thermostats control water flow and operating tem-
perature at lower speeds (below 2500 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 from the top of the exhaust
manifold on the cylinder block allows the constant
movement of water and/or air from the block. Cir-
culated water flows through a hose and tee-fitting,
exiting through the overboard indicator.
Operation
All models use a two-stage cooling system
design. The cooling system is dependent on water
pump pressure and controlled by thermostat and
pressure valve operation.
Cylinder Block / Cylinder Head
Cooling
The flow of water through the cooling system is
controlled by two thermostats and one pressure
valve. The pressure valve is connected by hoses
to the top of each cylinder head.
The thermostats and pressure valve control the
flow of water leaving the water passages of the
cylinder heads.
Pressure Relief Valve
009260
Thermostat
009261
NOTICE
Restricted or inadequate water flow through
the outboard reduces cooling system perfor-
mance and may lead to severe powerhead
damage.
1. Thermostats
2. Pressure valve assembly
009262
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