TM 5-3810-300-24&P-3
5.3
RADIATOR
The temperature of the coolant circulating through the
casionally, however, oil may be present requiring the use
engine is lowered by the action of the radiator and the
of a solvent, such as oleum, to loosen the dirt. The use
fan. The radiator is mounted in front of the engine so
of gasoline, kerosene, or fuel oil is NOT recommended
that the fan will draw air through it, thereby' lowering and
as a solvent. A spray gun is an f effective means of
maintaining the coolant temperature to the degree
applying the solvent to the radiator core. Use air to
necessary for efficient engine operation.
remove the remaining dirt. Repeat this process as many
times as necessary, then rinse the' radiator with clean
The life of the radiator will be considerably prolonged if
water and dry it with air.
the coolants used are limited to either clean, soft water
with a rust inhibitor or a mixture of water and a high
Another method of cleaning the radiator is the use of
boiling point type antifreeze. The use of any other type
steam or a steam cleaning device, if available. If the
antifreeze is not recommended.
foreign deposits are hardened, it may be necessary to
apply solvents.
To increase the cooling efficiency of the radiator, a metal
shroud is placed around the fan. The fan shroud must
The scale deposit inside the radiator is a result of using
be fitted airtight against the radiator to prevent re-
hard, high mineral content water in the cooling system.
circulation of the hot air drawn through the radiator. Hot
The effect of heat on the minerals in the water causes
air which is permitted to pass around the sides or bottom
the formation of scale, or hard coating, on metal surfaces
of the radiator and is again drawn through the radiator
within the radiator, thereby reducing the transfer of heat.
will cause overheating of the engine.
Some hard water, instead of forming scale, will produce
a silt-like deposit which restricts the flow of water. This
Another cause of overheating is slippage of the fan drive
must be flushed out at least twice a year --more often if
belts which is caused by incorrect belt tension, worn
necessary.
belts or worn fan belt pulley grooves, or the use of fan
belts of unequal length when two or more belts are used.
To remove the hardened scale, a direct chemical action
The belt tension and condition of the belts should be
is necessary.
A flushing compound such as
checked periodically.
salammoniac, at the specified rate of 1/4 pound per each
gallon of radiator capacity, should be added to the
A radiator that has a dirty, obstructed core or is leaking, a
coolant water in the form of a dissolved solution while the
leak in the cooling system, or an inoperative thermostat
engine is running. Operate the engine for at least 15
will also cause the engine to overheat. The radiator
minutes, then drain and flush the system with clean
must be cleaned, the leaks eliminated, and defective
water.
thermostats replaced immediately to prevent serious
damage from overheating.
Other flushing compounds are commercially available
and should be procured from a reliable source. Most
The external cleanliness of the radiator should be
compounds attack metals and should not remain in the
checked if the engine overheats and no other causes are
engine for more than a few minutes. A neutralizer should
apparent.
be used in the cooling system immediately after a de-
scaling solvent is used.
Cleaning Radiator
The radiator should be cleaned whenever the foreign
For extremely hard, stubborn coatings, such as lime
deposits are sufficient to hinder the flow of air or the
scale, it may be necessary to use a stronger solution.
transfer of heat to the air. In a hot dusty area, periodic
The corrosive action of a stronger solution will affect the
cleaning of the radiator will prevent a decrease in
thin metals of the radiator, thereby reducing its operating
efficiency and add life to the engine.
life. A complete flushing and rinsing is mandatory and
must be accomplished skillfully.
The fan shroud and grille should be removed, if possible,
to facilitate the cleaning of the radiator core.
After the solvent and neutralizer have been used and the
cooling system is flushed, completely drain the entire
An air hose with a suitable nozzle is often sufficient to
system again and fill it with clean, soft water plus a rust
remove loose dust from the radiator core. Oc-
inhibitor or high boiling point type antifreeze. After filling
the cooling system, inspect the radiator and engine for
water leaks.
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