DETROIT DIESEL 53
Cooling System 5
2. Attach a hose at the top of the radiator to lead water
Flushing
away from the engine.
The cooling system should be flushed each spring and
3. Attach a hose to the bottom of the radiator and
fall. The flushing operation cleans the system of
insert a flushing gun in the hose.
antifreeze solution in the spring and removes the
summer rust inhibitor in the fall, cleaning the system for
4. Connect the water hose of the gun to the water,
the next solution. The flushing operation should be
outlet and the air hose to the compressed air outlet.
performed as follows:
5. Turn on the water and, when the radiator is full. turn
1. Drain
the previous season's solution
from
the
on the air in short blasts, allowing the radiator to fill
engine.
between air blasts.
CAUTION: Apply air gradually. Do not
2. Refill with soft clean water.
exert more than 30 psi air pressure.
CAUTION: If the engine is hot, fill slowly
Too great a pressure may rupture a
to prevent rapid cooling and distortion
radiator tube.
of the engine castings.
6. Continue flushing until only clean water is expelled
3. Start the engine and operate it for 15 minutes to
from the radiator.
thoroughly circulate the water.
The cylinder block and cylinder head water passages
4. Drain the unit completely.
are reverse-flushed as follows:
5. Refill with the solution required for the coming
1. Remove the thermostats and the water pump.
season.
2. Attach a hose to the water inlet of the cylinder block
Cooling System Cleaners
to drain the water away from the engine.
If the engine overheats, and the fan belt tension and
3. Attach a hose to the water outlet at the top of the
water level have been found to be satisfactory, clean
cylinder block and insert the flushing gun in the hose.
and flush the entire cooling system. Remove scale
formation by using a reputable and safe de-scaling
4. Turn on the water and, when the water jackets are
solvent. Immediately after using the de-scaling solvent,
filled, turn on the air in short blasts, allowing the engine
neutralize the system with the neutralizer. It is important
to fill with water between air blasts.
descaler that the directions printed on the container of
the be thoroughly read and followed.
5. Continue flushing until the water from the engine.:
runs clean.
After the solvent and neutralizer have been used,
completely drain the engine and radiator and reverse-
If scale deposits in the radiator cannot be removed by
flush before filling the system.
chemical cleaners or reverse-flushing as outlined above,
it may be necessary to remove the upper tank and rod
Reverse-Flushing
out the individual radiator tubes with flat steel rods.
Circulate water through the radiator core from the
After the engine and radiator have been thoroughly
bottom to the top during this operation.
cleaned, they should be reverse-flushed. The water
pump should be removed and the radiator and engine
Miscellaneous Cooling System Checks
reverse-flushed separately to prevent dirt and scale
deposits clogging the radiator tubes or being forced
In addition to the above cleaning procedures, the other
through the pump. Reverse-flushing is accomplished by
components of the cooling system should be checked
hot water, under air pressure, being forced through the
periodically to keep the engine operating at peak
cooling system in a direction opposite to the normal flow
efficiency. The cooling system hoses, thermostats and
of coolant, loosening and forcing scale deposits out.
radiator pressure cap should be checked and replaced if
found to be defective.
The radiator is reverse-flushed as follows:
When water connection seals and hoses are installed,
be sure the connecting parts are properly aligned and
1. Remove the radiator inlet and outlet hoses and
replace the radiator cap.
1972 General Motors Corp.
August, 1972
SEC. 5 Page 5
