25 Maintenance Section Cooling System Specifications

Table 9

Caterpillar Minimum Acceptable Water Requirements

Property

Maximum Limit

ASTM Test

 

 

 

Chloride (Cl)

40 mg/L

“D512”,

(2.4 grains/US gal)

“D4327”

 

 

 

 

Sulfate (SO4)

100 mg/L

“D516”

(5.9 grains/US gal)

 

 

 

 

 

Total Hardness

170 mg/L

“D1126”

(10 grains/US gal)

 

 

 

 

 

Total Solids

340 mg/L

“D1888”

(20 grain/US gal)

 

 

 

 

 

Acidity

pH of 5.5 to 9.0

“D1293”

 

 

 

For a water analysis, consult one of the following sources:

•Caterpillar dealer

•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

•Pitting and erosion from cavitation of the cylinder liner

•Foaming of the coolant

Many additives are depleted during engine operation. These additives must be replaced periodically. This can be done by adding Supplemental Coolant Additives (SCA) to Diesel Engine Antifreeze/Coolant (DEAC) or by adding ELC Extender to Extended Life Coolant (ELC).

Additives must be added at the proper concentration. Overconcentration 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 and the cylinder liner

For optimum performance, Caterpillar recommends a 1:1 mixture of a water/glycol solution.

NOTICE

All Caterpillar diesel engines equipped with air-to-air aftercooling (ATAAC) require a minimum of 30 percent glycol to prevent water pump cavitation.

Note: Use a mixture that will provide protection against the lowest ambient temperature.

Note: 100 percent pure glycol will freeze at a temperature of −23 ￿C (−9 ￿F).

Most conventional heavy-duty coolant/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. See Tables 10 and 11.

Table 10

Ethylene Glycol

Concentration

Freeze

Boil

Protection

Protection

 

 

 

 

50 Percent

−36 ￿C (−33 ￿F)

106 ￿C (223 ￿F)

 

 

 

60 Percent

−51 ￿C (−60 ￿F)

111 ￿C (232 ￿F)

 

 

 

 

 

 

NOTICE

Do not use propylene glycol in concentrations that exceed 50 percent glycol because of propylene glycol’s reduced heat transfer capability. Use ethylene glycol in conditions that require additional protection against boiling or freezing.