TM 5-3895-359-14&P
with hot water, under air pressure, being forced through
Miscellaneous Cooling System
the cooling system in a direction opposite to the normal
flow of coolant, thus loosening and forcing the scale
Checks In addition to the above cleaning procedures,
deposits out.
the other components of the cooling system should be
checked periodically to keep the engine operating at
Reverse-flush the radiator as follows:
peak efficiency.
The thermostat and the radiator
pressure cap should be checked and replaced, if found
1. Remove the radiator inlet and outlet hoses and
defective.
replace the radiator cap.
When water connection seals and hoses are installed be
2. Attach a hose at the top of the radiator to direct the
sure the connecting parts are properly aligned and the
water away from the engine.
seal or hose is in its proper position before tightening the
clamps. All external leaks should be corrected as soon
3. Attach a hose to the bottom of the radiator and insert
as detected. The fan belt must be adjusted to provide
a flushing gun in the hose.
the proper tension and the fan shroud must be tight
against the radiator core to prevent recirculation of air
4. Connect the water hose of the gun to the water outlet
which may lower the cooling efficiency.
and the air hose to the compressed air outlet.
Contaminated Engine
5. Turn on the water and, when the radiator is full, turn
on the air in short blasts.
When the cooling system or lubricating system becomes
contaminated, it should be flushed thoroughly to remove
CAUTION:
the contaminants before the engine is seriously
Apply air gradually. Do not exert
damaged. One possible cause of such contamination is
a cracked oil cooler core. In such a case oil will be
more than 30 psi (207 kPa) air
forced into the cooling system while the engine is
pressure. Too great a pressure may
operating, and coolant will leak into the lubricating
rupture a radiator tube.
system when the engine is stopped.
6. Continue flushing until only clean water is expelled
Coolant contamination of the lubricating system is
from the radiator.
especially harmful to an engine during the cold season
when the cooling system is normally filled with an
Reverse-flush the cylinder block and cylinder head
ethylene glycol antifreeze solution. If mixed with the oil
water passages as follows: I. Remove the thermostat
in the crankcase, this antifreeze forms a varnish which
and the water pump.
quickly immobilizes moving engine parts.
2. Attach a hose to the water inlet of the cylinder block
To remove such contaminants from the engine, both the
to drain the water away from the engine.
cooling system and the lubrication system must be
thoroughly flushed as outlined below:
3. Attach a hose to the water outlet at the top of the
engine and insert the flushing gun in the hose.
4. Block the bottom opening and fill the coolant
If the engine has had a failure resulting in the
passages with water; then unblock the bottom opening
contamination of the cooling system with lubricating oil,
and blow the water from the engine with full air pressure
the following flushing procedure is recommended:
from the flushing gun.
1. Prepare a mixture of Calgon, or its equivalent, and
5. Again fill the engine cooling system with water and
water at the rate of two ounces (dry measure) to one
blow clean with full air pressure. Repeat this procedure
gallon of water.
until the flushing water runs clean.
2. Remove the engine thermostat to permit the Calgon
If the scale deposits in the radiator cannot be removed
and water mixture to circulate through the engine and
by chemical cleaners or reverse-flushing, it may be
the radiator.
necessary to remove the upper tank and rod out the
individual radiator tubes with flat steel rods. Circulate
3. Fill the cooling system with the Calgon solution.
water through the radiator core from the bottom to the
top during this operation.
4. Run the engine for five minutes.
10-6-4
