CG938H Wheel Loader. Manual - part 27

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IV    Maintenance of Engine’s Cooling System

 

4.1 Coolant 

Keeping normal working temperature of diesel engine will improve the efficiency of the 

engine. Therefore it is necessary to maintain the cooling system properly. Overheat, 

overcooling, pitting corrosion, gaseous cavitation, crack of cylinder end, piston sticking and 

blockage of radiator are common failures of the cooling system. 

z  It is suggested to add 30% anti-icing fluid into the cooling mixture. Under the working 

temperature of the engine, all kinds of water have causticity, regardless of the high 

concentration of the anti-icing fluid. 3%~ 6% coolant additives shall be added to protect 

the cooling system. 

z  Do not add coolant into the overheated engine, or not the engine will be damaged. Prior to 

adding the coolant upon request, the engine shall be cooled firstly.   

z  As the concentration of the additive exceeds 6%, and the sum of the additive’s 

concentration and the one of the anti-icing fluid exceeds 65%, sedimentation will be 

formed, and results in blockage of radiator’s pipe, engine’s overheat and inefficient 

sealing of water pump. 

z  If the machine is stored or transported to the area 0  below, the cooling system shall be 

℃

protected as per the possible minimal temperature. 

z  Under lower temperature, the specific gravity of the coolant shall be examined frequently 

so as to facilitate taking enough protective measures. 

z  If the coolant is polluted, the engineer is involved in overheat or radiator has foam, the 

cooling system shall be cleaned. 

z  Per 1500 hours or one year, the coolant shall be discharged, and the system shall be 

cleaned. And new coolant shall be added. 

z  In case the speed of adding coolant exceeds 20L/min, air bubbles of cooling system will 

be caused possibly. 

z  After adding the new coolant, start the engine and uncover the radiator until the coolant is 

up to the normal working temperature and the liquid level is stable. If necessary, more 

coolant shall be added in the system until reaching the proper liquid level. 

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4.2 Cooling Water 

z  If hard water or water with many calcium or manganese 

ions mixes with the silicon and phosphorus of the 

additive in the cooling system, indissoluble compound 

will be formed easily. 

z  The tendency that silicon and phosphorus form 

indissoluble compound will increase with the increase of 

the water’s hardness. After a series of heating and 

cooling circulation, the hard water or water with many 

calcium or manganese ions will form indissoluble 

compound easily. 

z  We suggest using distilled water or plasma water to weaken the possibility and severity of 

the formation of indissoluble compound.       

ppm= number of particles per one million

. 

z  Using the water that meets this requirement not always prevent the formation of the 

indissoluble compound, but reducing the rate of deposition for eligible level. 

 

4.3 Anti-icing Fluid 

z  The coolant shall adopt the eligible water and shall contain about 30% anti-icing fluid so 

as to maintain the operation temperature of water pump’s cavity for a higher efficiency of 

the water pump. 

z  To protect the possible minimal ambient temperature, antifreezing agent may be added in 

the coolant in advance. The amount of the antifreezing agent depends on the antifreezing 

agent purchased and possible minimal ambient temperature at the machine position. 

Nevertheless, the concentration of the antifreezing agent in the coolant shall not exceed 

60%. Over 60%, the antifreezing protection action on the engine will be weakened and 

the possibility of precipitation formation in the cooling system will be increased. 

z  Try best to buy anti-icing fluid with less silicate and proper coolant additive for heavy 

diesel engine. 

z  Add properly anti-icing fluid additive 

Adding the anti-icing fluid as make-up liquid into the cooling system’s liquid is a kind of 

Usable Water Minimally 

Ingredient of 

Water 

Limit gr/gal (ppm)

Chlorine 

(CL) 

Max. 2.4(40) 

Sulfate (SO

4

) Max. 

5.9(110) 

Total 

hardness 

Max. 10(170) 

Total 

 

granularity 

Max. 20(340) 

PH value 

5.5~9.0 

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unacceptable method. In this way, the concentration of the anti-icing fluid in the coolant will 

be increased. The mixture of water and antifreezing agent shall be added into the cooling 

system. 

Refer to the following table to determine the concentration of the anti-icing fluid (only as 

reference, please see the user’s manual of anti-icing fluid for details) 

Concentration of Anti-icing Fluid 

Protection 

Temperature 

Concentration 

-15  above

℃

 

30% anti-icing fluid, 70% 

water 

-23 above

℃

 

40% anti-icing fluid, 60% 

water 

-37 above  

℃

 

50% anti-icing fluid, 50% 

water   

-51 above

℃

 

60% anti-icing fluid, 40% 

water 

The different anti-icing fluids and additives made by different manufacturers shall not be 

mixed together. In case the anti-icing fluid and additive must be replaced, the cooling system 

shall be cleaned, and then the mixed anti-icing fluid and additive may be added. 

z  Ancillary coolant additive 

The coolant additive is used to prevent rust, dust, pitting corrosion and corrosion of the 

engine’s parts due to contact with the coolant. Most anti-icing fluid has no enough ancillary 

coolant additive. 

In the coolant, the additive or corresponding liquid of proper amount shall be added. The 

coolant cannot be used separately, except the anti-icing fluid with the additive above. Under 

this circumstance, the additive may not be added. Nevertheless, in the process of maintenance, 

the additive shall be added. 

As the coolant additive is used, the concentration in the cooling system may increase by 

3%~6% to prevent corrosion. 

In order to excessive antirust in the cooling system of the engine, the concentration of 

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the coolant additive shall not exceed the maximum 6% we recommend. 

For a higher concentration of the additive, precipitation may be formed possibly at the 

high-temperature surface of the cooling system, and an adiabatic layer may be formed to 

weaken the heat exchange performance of the engine. The decrease of the heat exchange rate 

will possibly cause the crack of the cylinder end and other high-temperature parts. The higher 

concentration of the additive will also increase wear of the water pump’s seal.   

As the premixed coolant of the anti-icing liquid is not used, the coolant additive shall be 

added.  

As the coolant is added into the new or reworked engine for the first time, if the 

antifreezing agent above is not used, 1L ancillary coolant additive or corresponding matter 

shall be added in each 30L coolant, so the concentration of the ancillary additive in the cooling 

system occupies up 3%~6%. 

In order to maintain the concentration of 3%~6%, every 250 hours or in oil replacement 

(later or first), the ancillary additive shall be added.