European International Journal of Multidisciplinary Research
and Management Studies
42
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TYPE
Original Research
PAGE NO.
42-46
DOI
OPEN ACCESS
SUBMITED
23 January 2025
ACCEPTED
26 February 2025
PUBLISHED
25 March 2025
VOLUME
Vol.05 Issue03 2025
COPYRIGHT
© 2025 Original content from this work may be used under the terms
of the creative commons attributes 4.0 License.
Engine Cooling System
Maintenance
Avliyokulov J.S.
Tashkent State Transport University, Uzbekistan
Magdiyev Sh.P.
Tashkent State Transport University, Uzbekistan
Tadjiyev R.D.
Tashkent State Transport University, Uzbekistan
Ashuraliyev E.Sh.
Tashkent State Transport University, Uzbekistan
Abstract:
The efficiency and longevity of modern
automobile engines depend significantly on their
thermal conditions, especially in desert-sandy areas
where overheating is a frequent issue. The cooling
system plays a crucial role in maintaining optimal
thermal conditions, and its reliability is influenced by
factors such as water pump efficiency, radiator
cleanliness, and coolant quality. The accumulation of
scale within the cooling system can severely impact heat
dissipation, leading to engine wear and possible failure.
Various chemical and mechanical methods are available
for descaling and flushing the cooling system, thereby
improving engine performance and preventing
overheating. Additionally, the use of softened water and
anti-corrosive additives can enhance the durability of
the cooling system. This paper discusses the
maintenance procedures, descaling techniques, and
best practices for ensuring efficient engine cooling.
Keywords:
Engine cooling system, overheating, scale
formation, descaling, water hardness, radiator
maintenance, thermal efficiency.
Introduction:
The cooling system of an automobile
engine is essential for maintaining optimal operational
temperatures and preventing overheating. This is
particularly
important
in
high-temperature
environments, such as desert-sandy areas, where
excessive heat can negatively impact engine
performance. The engine's thermal stability depends on
several factors, including load conditions, ambient air
European International Journal of Multidisciplinary Research
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European International Journal of Multidisciplinary Research and Management Studies
temperature, and the functionality of the cooling
system.
A properly functioning cooling system ensures that
excess heat is effectively dissipated, preventing wear
and tear on engine components. However, issues such
as scale formation, coolant leaks, and radiator clogging
can lead to thermal inefficiencies. Scale deposits on the
walls of the cooling jacket significantly reduce heat
transfer due to their low thermal conductivity,
resulting in increased engine stress and potential
failure. This paper explores the importance of
maintaining the cooling system, methods for removing
scale, and best practices for using water and chemical
treatments to enhance system reliability.
Research
High thermal stress of engine operation occurs due to
the harmful effect of scale, formed on the walls of the
cooling system jacket. This is explained by the fact that
the thermal conductivity coefficient of scale is
approximately 20-30 times less than the thermal
conductivity coefficient of cast iron, steel or brass.
Consequently, in the presence of scale, the conditions
for heat removal from the cylinder-piston group of the
engine worsen, and the resulting overheating of the
parts increases the intensity of their wear.
The presence of a scale layer in the engine cooling
jacket is the cause of cylinder scoring and clogging of
the radiator tubes. To remove scale and flush the
cooling system, you can use a 6% lactic acid solution or
a 10% caustic soda solution. The time required to
remove scale with lactic acid is 1-3 hours, and with
caustic soda 6-8 hours. Soda-kerosene solutions are
widely used to flush the cooling system of diesel
engines. Such solutions are prepared using caustic
soda, kerosene and water. The composition of the
solution: caustic soda - 7, kerosene - 2.3, water - 90.7%.
To flush one engine, on average, the following is
required: soda 4.8-5.8, kerosene 1.5-1.9, water 60-75
liters. The prepared solution is poured into the cooling
system, the engine is started and allowed to run at
medium speed for 5-10 minutes, the engine is stopped
and the solution is kept in the cooling system for 10-12
hours; the engine is started again and warmed up; the
solution is drained from the cooling system; the cooling
system is flushed with water in a volume of two to
three times the capacity of the system.
The clogging of the radiator and engine cooling system
can be determined by filling it with water coming from
a measuring tank installed 300-400 mm above the
radiator neck and connected to it by a flexible hose. In
this case, the time and volume of water required to fill
the entire cooling system or the radiator and the
cylinder block jacket space separately are determined.
The data obtained are compared with the time and
volume of water required to fill the engine cooling
system of a new car of the same brand.
The cooling system can also be cleaned by using an air-
water jet in the direction opposite to the circulation of
liquid in the cooling system. To do this, the cooling liquid
is released from the cooling system, the upper and
lower connecting hoses are disconnected and a special
tip is installed in the lower radiator pipe or the engine
block pipe, through which water and air are supplied
under pressure. The pressure of the air supplied to the
radiator should not exceed 0.5-0.75 N/cm2, since at
higher pressure the radiator may be destroyed. Flushing
should be done until clean water without traces of silt
deposits comes out of the radiator neck. It is advisable
to perform this method of cleaning the cooling system
after treating the system with special flushing solutions.
The cooling system of most modern automobile engines
is closed, i.e. sealed, due to which the pressure in it
exceeds atmospheric. An increase in pressure by every
0.1 N/cm2 above atmospheric increases the boiling
point of water by 2.4-2.5 °C. To prevent excessive
pressure in the system, a safety valve is installed in the
radiator cap. Usually, caps are used that provide excess
pressure of 0.28 and 0.49 N/cm2. The boiling point of
water with the first cap will be 106.7 °C, with the second
111.7 °C.
Increasing the water temperature in the cooling system
improves engine efficiency, which reduces fuel
consumption, and excess pressure prevents cavitation,
especially in the low-pressure zone of the water pump.
When preparing for summer operation, the radiator cap
should be checked for tightness of the neck closure and
correct operation of the safety valve. Cooling system
caps can be checked with a device (Fig. 1), consisting of
a pump with a pressure gauge installed on it. In this case,
the tested cap is fixed in the device, and the pump
creates the required pressure, which should be stable
for 10 seconds.
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Figure 1.
Device for checking the steam-air valves of the radiator caps and the
condensation tank of the cooling system: 1-test plug; 2-device div; 3-pump; 4-tray;
5-test pressure gauge; 6-test drain tube
When checking the engine cooling system for leaks,
this device is installed on the radiator neck and, using
a pump, excess pressure of 0.6-0.7 N/cm2 is created in
the cooling system, under the action of which leaks can
be detected. Then it is advisable to start the engine and
warm it up at idle speed to 45-50°C.
In this case, the fluctuation of the pressure gauge
needle indicates the presence of an internal leak in the
cylinder head gasket. However, as operating practice
has shown, if the system is normally filled, but the
water boils, then the reasons for the increase in
temperature in the cooling system may be, for
example: excessive back pressure at the outlet,
incorrect adjustment of the brakes and clutch
mechanism, malfunction of the valves of the engine
distribution
mechanism,
abnormal
clearances
between pistons and cylinders, incorrect ignition
setting, worn spark plugs.
During the process of preparing the vehicle for
operation, all of the above mechanisms must be
carefully checked and any faults detected must be
eliminated. When operating vehicles in hot climates,
intensive evaporation of water from the cooling
system occurs, which makes it necessary to
periodically top up the radiators with water. Frequent
refilling of the cooling system with water increases the
intensity of scale formation, especially when using
water that is highly hard and contaminated with
mechanical impurities. Using a closed cooling system,
you can significantly reduce (by 70-80%) the water
consumption for refilling.
Water used to fill engine cooling systems may contain
a large number of various dissolved substances,
consisting mainly of calcium and magnesium
carbonates, which cause water hardness. Depending
on the content of various salts and carbonate
compounds of calcium and magnesium in water,
temporary and permanent hardness are distinguished.
Temporary hardness is caused by the presence of
bicarbonate salts of calcium and magnesium
(bicarbonates) in water, which, when boiling water,
become insoluble and are deposited on the walls of
vessels! When filling the cooling system with water with
a high content of salts of temporary hardness without
preliminary treatment, the salts settle on the walls of
the engine cooling jacket and radiator tubes and form
scale. Therefore, it is recommended to use clean water
with a minimum content of calcium and magnesium
salts to fill the cooling system. Before filling the cooling
system with water having high temporary hardness, it
should be pre-boiled in hot water boilers or water-oil
heaters.
Permanent water hardness is caused by the presence of
soluble salts in it, which do not precipitate when boiling
water. These salts are less dangerous for the cooling
system. However, a large number of salts of permanent
hardness destroys radiator tubes and thermostats.
General hardness consists of temporary, eliminated by
boiling, and permanent, which remains after boiling.
The unit of hardness is milligram equivalent per liter
(mg-eq/l), which is equal to the content of 20.04 mg of
calcium carbonate salts or 12.16 mg of magnesium salts
in 1 liter of water. Sometimes water hardness is
expressed in old units of hardness - German degrees.
One degree of hardness corresponds to the content of
10 mg of calcium oxide (quicklime) in 1 liter of water.
Water with a hardness of less than 8° is considered soft,
from 8 to 10° - medium hardness, from 12 to 30° - hard
and over 30° - very hard. Water with a hardness of up to
12 mg-eq/l or up to 20° is suitable for filling the engine
cooling system without artificially reducing its hardness.
If the water hardness is higher than 12 mg-eq/l, then
before filling the vehicle, it is necessary to reduce its
hardness by preliminary boiling or chemical treatment.
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You can reduce scale formation by adding up to 3 mg
of hexametaphosphate powder per 1 liter of water.
You can use calcined soda (Na2CO3) and trisodium
phosphate (NaPO3) to soften water, which are capable
of releasing salts from water that cause its temporary
hardness.
Washing soda and trisodium phosphate should be
dissolved in water in small quantities before adding it
to the cooling system:
• to soften medium
-hard water 1.0 g NaPO3 per 1 liter;
• to soften hard water from 1.5
-2.0 g per 1 liter.
The cooling system can only be filled with settled
water. It is not recommended to dissolve these
substances directly in the cooling system, since the
precipitation can clog the radiator tubes.
Soften the water as follows. Pour the required amount
of trisodium phosphate into a barrel of water and stir
until completely dissolved. Then the water is settled for
2-3 hours, after which it is ready for use. To soften the
water, you can use a softening mixture consisting of
sodium phosphate, caustic soda and oak extract.
The consumption of chemicals depends on the hardness
of the water (Table 1). Prepare a solution from a mixture
of substances as follows. First add the required amount
of caustic soda and oak extract to a clean bucket of hot
water, and then add sodium phosphate.
Table 1.
Water softening chemical consumption
Chemicals
Chemical consumption per 10 liters of water of varying hardness, g
15°
20°
25°
30°
over 30°
Sodium Phosphate
1
1,5
2,0
2,0
2.0
Caustic Soda
2,5
3,0
3,0
3,5
4,0
Oak extract
0,5
0,5
0,5
0,5
0,5
After the mixture has completely dissolved, mix it with
the required amount of water and let it settle for 2-3
hours. When repairing the cooling system, softened
water must be collected in a separate container.
The most effective substance for reducing scale
formation is chrompic acid (K2Cr2O7). This substance
easily dissolves in water and forms a protective oxide
film on the parts, which protects the parts from
corrosion. Chrompic acid can be dissolved directly in
the cooling system in an amount of 0.5% of its volume.
It is not allowed to use water whose hardness has not
been established to fill the cooling system, as this may
lead to intensive scale formation and corrosion of the
radiator tubes. In order to reduce the consumption of
cooling water, a condensation tank is installed on cars,
the installation of which does not require design
changes in the standard cooling system. Steam emitted
from the radiator enters the condensation tank,
where, cooling and condensing, it again enters the
engine cooling system.
When installing a condensation tank on a vehicle, the
following conditions must be met: install the tank on
the vehicle, if possible, so that it is cooled by the air
flow; place the tank at the level of the upper part of the
radiator; securely fasten the tank; the connecting
tubes must not have sharp bends; ensure a tight
connection between the condensation tank and the
radiator, while all hoses connecting the radiator and
the condensation tank are installed on nitro paint;
coolant is simultaneously poured into the radiator and
1.5-2 liters of it into the condensation tank so that the
end of the tube inside the tank is always below the liquid
level; the radiator plug, as well as the plug on the
condensation tank, must be tightly screwed in at all
times; when draining coolant from the cooling system,
it must also be drained from the condensation tank
(through the tap located in the bottom of the tank).
CONCLUSION
Maintaining the engine cooling system is critical for
ensuring optimal performance, especially in high-
temperature conditions. The presence of scale deposits
in the cooling system can drastically reduce heat
dissipation, leading to engine overheating and increased
wear on components. Regular descaling using chemical
solutions such as lactic acid, caustic soda, and soda-
kerosene mixtures can effectively clean the system and
restore its efficiency. Additionally, using softened water
and anti-corrosion additives minimizes the risk of scale
formation and extends the lifespan of the cooling
components. By implementing proper maintenance
practices and regularly inspecting the cooling system,
vehicle operators can significantly improve engine
reliability, reduce fuel consumption, and enhance
overall vehicle performance. Considering the high soil
hardness of water in hot climates due to the high salt
content, it is necessary to soften the water in a timely
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manner and use effective substances to reduce scale
formation, which will ensure reliable operation of the
engine cooling system.
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