TM 5-3810-300-24&P-3
5 COOLING SYSTEM
Reverse-flush the radiator as follows:
Miscellaneous Cooling System Checks
1. Remove the radiator inlet and outlet hoses and
In addition to the above cleaning procedures, the other
replace the radiator cap.
components of the cooling system should be checked
periodically to keep the engine operating at peak
2. Attach a hose at the top of the radiator to direct the
efficiency. The thermostat and the radiator pressure cap
water away from the engine.
should be checked and replaced, if found defective. The
cooling system hoses should be inspected and any hose
3. Attach a hose to the bottom of the radiator and
that feels abnormally hard or soft should be replaced
insert a flushing gun in the hose.
immediately.
4. Connect the water hose of the gun to a water outlet
When water connection seals and hoses are installed be
and an air hose to the compressed air outlet.
sure the connecting parts are properly aligned and the
seal or hose is in its proper position before tightening the
5. Turn on the water and, when the radiator is full, turn
clamp. All external leaks should be corrected as soon as
on the air in short blasts.
detected. The fan belt must be adjusted to provide the
proper tension, and the fan shroud must be tight against
CAUTION: Apply air gradually. Do not exert
the radiator core to prevent recirculation of air which may
more than 30 pounds (p.s.i.) air pressure. Too
lower cooling efficiency.
great a pressure may rupture a radiator tube.
Contaminated Engine
6. Continue flushing until only clean water is expelled
When the cooling system or lubricating system becomes
from the radiator.
contaminated, it should be flushed thoroughly to remove
the contaminants before the engine is seriously
Reverse-flush the cylinder block and cylinder head
damaged. One possible cause of such contamination is
water passages as follows:
a cracked oil cooler core. In such a case, oil will be
forced into the cooling system while the engine is
1.
Remove the thermostat and the water pump.
operating, and coolant will leak into the lubricating
system when the engine is stopped.
2. Attach a hose to the water inlet of the cylinder block
to drain the water away from the engine.
Coolant contamination of the lubricating system is
especially harmful to an engine during the cold season
3. Attach a hose to the water outlet at the top of the
when the cooling system is normally filled with an
engine and insert a flushing gun in the hose.
ethylene glycol antifreeze solution. If mixed with the oil
in the crankcase, this antifreeze forms a varnish which
4. Block the bottom opening and fill the coolant
quickly immobilizes moving engine parts.
passages with water; then unblock the bottom opening
and blow the water from the engine with full air pressure
To remove such contaminants from the engine, both the
from the flushing gun.
cooling system and the lubricating system must be
thoroughly flushed as outlined below:
5. Again fill the engine cooling system with water and
blow clean with full air pressure. Repeat this procedure
COOLING SYSTEM
until the flushing water runs clean.
If the engine has had a failure resulting in the
contamination of the cooling system with lubricating oil,
If the scale deposits in the radiator cannot be removed
the following flushing procedure is recommended:
by chemical cleaners or reverse-flushing, it may be
1. Prepare a mixture of Calgon, or its equivalent, and
necessary to remove the upper tank and rod out the
water at the rate of two ounces (dry measure) to one
individual radiator tubes with flat steel rods. Circulate
gallon of water.
water through the radiator core from the bottom to the
2. Remove the engine thermostat to permit Calgon
top during this operation.
and water mixture to circulate through the engine and the
radiator.
3. Fill the cooling system with the Calgon solution.
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