
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 11 and refer to table 12 .
Table 11
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 12
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.
Note:
Some commercially available coolants are
based on alternative fluids, such as 1, 3-propanediol
(beta-propylene glycol, PDO), glycerin (glycerol) or
mixtures of these alternatives with ethylene/
propylene glycols. At the time of publication of this
document no industry standard exists for coolants
based on these chemicals. Until such standard/
specifications are published and evaluated by
Perkins, use of PDO, glycerine or other alternative
coolants is not recommended in Perkins diesel
engines.
Coolant Recommendations
• ELC
Extended Life Coolant
• SCA
Supplement Coolant Additive
• ASTM
American Society for Testing and
Materials
ELC - extended life coolant. A coolant that relies on
organic inhibitors for corrosion and cavitation
protection. Also called OAT coolant (Organic Acid
Technology).
SCA - supplemental coolant additive, concentrated
inorganic inhibitor package.
Extender - concentrated organic inhibitor package.
Conventional Coolant - a coolant that relies on
inorganic inhibitors for corrosion and cavitation
protection.
Hybrid Coolant - a coolant in which the corrosion and
cavitation protection is based on a mixture of organic
and inorganic inhibitors.
The following coolants are recommended for used in
Perkins diesel engines:
Preferred
– Perkins ELC
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