hoses, thermostat, radiator fan, fan switch, and fan relay.
There are three modes of coolant circulation: (a) cold
engine, (b) normal operating temperature, (c) hot engine.
When the engine is cold such as during warming up, the
water is cold, and the thermostat is closed. The water,
forced out from the water pump, goes up around the
cylinders and through the cylinder head, then takes a
short cut through the bypass pipe and returns to the
This brings a cold engine up to proper temperature
quickly. While the engine is in normal operating tem·
perature range, the thermostat opens only partially.
The size of the valve opening of the thermostat, and
the amount of water flowing to the
depending on water temperature. The higher the water
temperature becomes, the more water goes through
the radiator, keeping the temperature of the returning
When the water temperature exceeds
the normal operating temperature, the thermostat opens
fully to allow all water to flow through the radiator.
If the water temperature goes up beyond the predeter·
mined level, the thermostatic fan switch conducts to
operate the fan relay. The fan relay closes its
completes the fan motor circuit, and the cooling fan
turns to speed up the cooling action of the
When the water cools down; the fan switch cuts the
relay current, and the fan stops. This electric cooling
fan system saves engine power, and reduces the battery
fan and fan switch are
connected dlrecdy to the battery. The
radiator tan may start even if the ignition switch is
off. NEVER TOUCH THE RADIATOR FAN UNTI L
THE ENGINE COMPLETELY COOLS
BEFORE THE ENGINE COOLS
COULD CAUSE INJURY FROM THE FAN BLADES.
By circulating in the cooling system, the coolant
transfers the heat generated at the engine to the radiator.
To protect the cooling system (consisting of the aluminum
engine and radiator) from rust and corrosion, the use of
corrosion and rust inhibitor chemicals in the water is
If coolant contain ing corrosion and rust
inhibitor chemicals is not used, over a period of time,
the cooling system accumulates rust and scale in the
water jacket and radiator. This will clog up the water
passages, and considerably reduce the efficiency of the
~s~ coolant cont~i!,ing corrosio~ in-
L. _ _ _ _ • •
hlblton made specIfIcally for aluminum
engines and radiaton in accordance with the instructions
of the manufactures.
Chemicals are harmful to the
Soft or distilled water must be used with the inhibitor
chemicals and the antifreeze (see below for antifreeze)
in the cooling system.
~ :"':~d .:!era!~~~t:~n ~~ ~:e:;t~!
passages, and considerably reduces the efficiency of the
If the lowest ambient temperature encountered falls
below the water freezing point in the winter, protect
the cooling system against engine and radiator freeze·up,
as well as from rust and corrosion. Use a permanent
type of antifreeze (soft water and ethylene glycol plus
corrosion and rust inhibitor chemicals for aluminum
engines and radiators) in the cooling system. On the
mixture ratio of coolant, choose the suitable one reo
ferring the relation between freezing point and strength
directed on the container.
~ ~e;~:e~!vety:~-C::!ro~~~~r:~~e a~;i-r~~
properties. When it is diluted excessively, it looses its
Dilute a permanent type of
antifreeze in accordance with the instructions of the
NOTE: A permanent type of antifreeze is installed in
the cooling system when shipped.
It is colored green,
includes the 43% solution of ethylene glycol, and has
the freezing point of
Visually inspect the coolant in the reserve tank. If
small wh itish cotton-like clusters are observed, aluminum
parts in the cooling system are corroded. The brownish
color of the coolant indicates rusting of steel parts. In
these cases, flush the cooling system (Pg. 208).
If the coolant gives off an abnormal smell when
changing, check for a cooling system leak (Pg. 209).
It may be caused by exhaust gas leaking into the cooling
NOTE: Be sure to inspect the coolant at the reserve
If the coolant is checked at the radiator by
removing the radiator cap, the air must be bled from
the cooling system
Water Pump, Mechanical Seal
The water pump lets the coolant circulate in the cool·
The mechanical seal prevents the coolant
from leaking along the pump shaft.
If the mechanical seal is damaged
the coolant leaks
through the seal, and the leaking coolant is drained
through the passage into the cylinder block.
A. Drainage Outlet