These failures can be avoided with correct cooling
system maintenance. Cooling system maintenance is
as important as maintenance of the fuel system and
the lubrication system. Quality of the coolant is as
important as the quality of the fuel and the lubricating
oil.
Coolant is normally composed of three elements:
Water, additives, and glycol.
Water
Water is used in the cooling system to transfer heat.
Distilled water or deionized water is
recommended for use in engine cooling systems.
DO NOT use the following types of water in cooling
systems: Hard water, softened water that has been
conditioned with salt and sea water.
If distilled water or deionized water is not available,
use water with the properties that are listed in Table 6
.
Table 6
Acceptable Water
Property
Maximum Limit
Chloride (Cl)
40 mg/L
Sulfate (SO
4
)
100 mg/L
Total Hardness
170 mg/L
Total Solids
340 mg/L
Acidity
pH of 5.5 to 9.0
For a water analysis, consult one of the following
sources:
• Local water utility company
• Agricultural agent
• Independent laboratory
Additives
Additives help to protect the metal surfaces of the
cooling system. A lack of coolant additives or
insufficient amounts of additives enable the following
conditions to occur:
• Corrosion
• Formation of mineral deposits
• Rust
• Scale
• Foaming of the coolant
Many additives are depleted during engine operation.
These additives must be replaced periodically.
Additives must be added at the correct concentration.
Over concentration of additives can cause the
inhibitors to drop out-of-solution. The deposits can
enable the following problems to occur:
• Formation of gel compounds
• Reduction of heat transfer
• Leakage of the water pump seal
• Plugging of radiators, coolers, and small passages
Glycol
Glycol in the coolant helps to provide protection
against the following conditions:
• Boiling
• Freezing
• Cavitation of the water pump
For optimum performance, Perkins recommends a
1:1 mixture of a water/glycol solution.
Note:
Use a mixture that will provide protection
against the lowest ambient temperature.
Note:
100 percent pure glycol will freeze at a
temperature of −13 °C (8.6 °F).
Most conventional antifreezes use ethylene glycol.
Propylene glycol may also be used. In a 1:1 mixture
with water, ethylene and propylene glycol provide
similar protection against freezing and boiling. Refer
to Table 7 and refer to table 8 .
Table 7
Ethylene Glycol
Concentration
Freeze Protection
50 Percent
−36 °C (−33 °F)
60 Percent
−51 °C (−60 °F)
NOTICE
Do not use propylene glycol in concentrations that
exceed 50 percent glycol because of the reduced
heat transfer capability of propylene glycol. Use ethyl-
ene glycol in conditions that require additional protec-
tion against boiling or freezing.
Table 8
Propylene Glycol
Concentration
Freeze Protection
50 Percent
−29 °C (−20 °F)
To check the concentration of glycol in the coolant,
measure the specific gravity of the coolant.
36
SEBU9077-01
