International Harvester Company CUB Operator's Manual page 23

COOLING SYSTEM
The thermo- siphon principle is used for
circulating water in the cooling system. (The
temperature of the water governs the rate of
circulation.) Therefore, a thermostat and a
water pump are not required.
When the 1;ractor is shipped from the fac-
tory it is equipped with a nonpressure-type
radiator cap.
A pressure-type radiator cap is available
from your International Harvester dealer as a
replacement for the regular production radi-
ator cap, if so desired.
(I ~
Caution must be exercised in removing
~ . the pressure-type radiator cap when
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the water in the cooling system is hot.
See instructions in the following section.
The water is circulated through the engine
block. cylinder head. and radiator by the
thermo- siphon rnethod. As the engine warms
up. the water is heated. expands. and circu-
lates back through the radiator where the
water is cooled before again circulating
through the engine.
When the radiator is equipped with a pres-
sure-type radiator cap, the cooling system
operates under pressure which is controlled
by means of a regulating valve
b~lt
into the
radiator cap. Always use clean water (soft or
rain wat.er if possible).
FILLING THE COOLING SYSTEM
Be sure the radiator drain plug
(lIIust.
22) Is
closed; then fill the radiator to a level slightl;
below the bottom of the filler neck, when
equipped with a nonpressure-type radiator cap
or to a level approximately 2-inches below the
top of the filler neck, when equipped with a
pressure-type radiator cap. Filling the radi-
ator to this level will allow for expansion of
the coolant under normal operating conditions.
Use clean water; soft or rain water is recom-
mended, as it does not contain alkali, which
forms scale and eventually clogs passages.
Before replacing the filler cap, be sure to
remove any chaff or dirt particles which may
be on the gasket surface or cap, and tighten
the cap clockwise to the stop.
Note:
A pressure -cooled system will not
operate properly unless the cooling system is
tight.
21
The gasket surface must be in good condi-
tion. The cap must be properly tightened to
the stop, and the system must not have·loose
connections or leaks. Unless these instruc-
tions are followed, pressure will not be main-
tained, and loss of water and consequent·over-
heating will result. When draining the radia-
tor, always remove the filler cap to premit
complete drainage.
If the regulating valve is faulty, :J:"epIace the
radiator cap with a new one of the same type.
Do not attempt to repair or replace any of
the regulating valve parts.
If the engine is to be operated in freezing
temperatures, refer to "Cold Weather Pre-
cautions. "
ADDING WATER TO THE COOLING SYSTEM (When
Equipped w'ithe Pressure-Type Radiator Cap)
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Caution!
If the water in the cooling sys-
~
tem is hot and water is to be added, ob-
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serve the following:
Turn radiator cap "A"
(lIIust.
21) slowly
counterclockwise to the safety stop to allow
the pressure of any steam to escape; then
press down on the cap and continue to turn
until the cap is free to be removed.
"A" Radiator cap.
"·B" Filler cap gasket.
"c"
Filler neck.
"0" Upper water tank.
"E" Overflow pipe.
lIIust.
21
Water level In pressure-cooled radiator.