DETROIT DIESEL
Engine Systems
pump should be removed and the radiator and engine
all of the drain cocks open until refilling the cooling
reverse-flushed separately to prevent dirt and scale
system.
deposits clogging the radiator tubes or being forced
The exhaust manifolds of marine engines are cooled
through the pump. Reverse-flushing is accomplished
by the same coolant used in the engine. Whenever the
by hot water, under air pressure, being forced through
engine cooling system is drained, each exhaust
the cooling system in a direction opposite to the
manifold drain cock, located on the bottom near the
normal flow of coolant, loosening and forcing scale
exhaust outlet, must be opened.
deposits out.
Raw water pumps are drained by loosening the cover
The radiator is reverse-flushed as follows:
attaching screws. It may be necessary to tap the raw
water pump cover gently to loosen it. After the water
1. Remove the radiator inlet and outlet hoses and
has been removed, tighten the screws.
replace the radiator cap.
2. Attach a hose at the top of the radiator to lead
Flushing
water 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, preparing the
4. Connect the water hose of the gun to the water
cooling system for a new solution. The flushing
outlet and the air hose to the compressed air outlet.
operation should be performed as follows:
5. Turn on the water and, when the radiator is full,
1. Drain the previous season s solution from the
turn on the air in short blasts, allowing the radiator to
engine.
fill between air blasts.
2. Refill the cooling system with soft clean water. If the
CAUTION: Apply air gradually. Do not exert
engine is hot, fill slowly to prevent rapid cooling and
more than 30 psi (207 kPa) air pressure. Too
distortion of the engine castings.
great a pressure may rupture a radiator tube.
3. Start the engine and operate it for 15 minutes to
circulate the water thoroughly.
6. Continue flushing until only clean water is expelled
from the radiator.
4. Drain the cooling system completely.
The cylinder block and cylinder head water passages
5. Refill the system with the solution required for the
are reverse-flushed as follows:
coming season,
1. Remove the thermostat and the water pump.
Cooling System Cleaners
2. Attach a hose to the water inlet of the cylinder block
to drain the water away from the engine.
If the engine overheats and the fan belt tension and
water level are satisfactory, clean and flush the entire
3. Attach a hose to the water outlet at the top of the
cooling system. Remove scale formation by using a
cylinder block and insert the flushing gun in the hose.
quality de-scaling solvent. Immediately after using the
solvent, neutralize the system with the neutralizer. It is
4. Turn on the water and, when the water jackets are
important that the directions printed on the container
filled, turn on the air in short blasts, allowing the
of the de-scaling solvent be thoroughly read and
engine to fill with water between air blasts.
followed.
5. Continue flushing until the water from the engine
After the solvent and neutralizer have been used,
runs clean.
completely drain the engine and radiator and reverse-
flush before filling the cooling system.
If scale deposits in the radiator cannot be removed by
chemical cleaners or reverse-flushing as outlined
above, it may be necessary to remove the upper tank
Reverse-Flushing
and rod out the individual radiator tubes with flat steel
rods. Circulate water through the radiator core from
After the engine and radiator have been thoroughly
the bottom to the top during this operation.
cleaned, they should be reverse-flushed. The water
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