33 Maintenance Section Cooling System Specifications

When a heavy-duty coolant/antifreeze is used, treat the cooling system with three to six percent Caterpillar SCA by volume. For more information, see this publication, “Conventional Coolant/Antifreeze Cooling System Maintenance” topic (Maintenance Section).

If Caterpillar SCA is not used, select a commercial SCA. The commercial SCA must provide a minimum of 1200 mg/L or 1200 ppm (70 grains/US gal) of nitrates in the final coolant mixture.

Coolant/antifreeze that meets “ASTM D5345” or

“ASTM D4985” specifications MAY require treatment with SCA at the initial fill. These coolants WILL require treatment with SCA on a maintenance basis.

When concentrated coolant/antifreeze is mixed, Caterpillar recommends mixing the concentrate with distilled water or with deionized water. If distilled water or deionized water is not available, water which has the required properties may be used. For the water properties, see this publication, “General Coolant Information” topic (Maintenance Section).

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•Cavitation erosion of the cylinder liner

•Foaming of the coolant

If Caterpillar SCA is not used, select a commercial SCA. The commercial SCA must provide a minimum of 2400 mg/L or 2400 ppm (140 grains/US gal) of nitrates in the final coolant mixture.

The quality of the water is a very important factor in this type of cooling system. Distilled water

or deionized water is recommended for use in cooling systems. If distilled water or deionized water is not available, use water that meets the minimum requirements that are listed in the table for recommended water properties in this publication, “General Coolant Information” topic (Maintenance Section).

A cooling system that uses a mixture of SCA and water only needs more SCA than a cooling system that uses a mixture of glycol and water. The SCA concentration in a cooling system that uses SCA and water should be six to eight percent by volume. Refer to Table 22 for the amount of SCA that is required for various capacities of the cooling system.

Water/Supplemental Coolant Additive (SCA)

SMCS Code: 1350; 1352; 1395

NOTICE

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

NOTICE

Never use water alone without Supplemental Coolant Additives (SCA) or without inhibited coolant. Water alone is corrosive at engine operating temperatures. Water alone does not provide adequate protection against boiling or freezing.

Note: Premix the coolant solution in order to provide protection to the lowest ambient temperature that is expected.

Note: Pure undiluted antifreeze freezes at −23 ￿C (−9 ￿F).

In engine cooling systems that use Supplemental Coolant Additive (SCA) and water alone, Caterpillar recommends the use of SCA. SCA helps to prevent the following conditions from occurring:

•Corrosion

•Formation of mineral deposits