NOTICE Never use water alone without Supplemental Coolant Additive SCAs or inhibited coolant. Water alone is corrosive at engine operating temperatures and does
not provide adequate boil protection.
Distilled water or deionized water is recommended for use in cooling systems. Do not use hard tap water or salt softened tap water in engine cooling systems. If distilled
water or deionized water is not available, use water that meets the minimum requirements that are listed in the following table.
Caterpillar Recommended Quality Limits Water Property
grains3.8 L ppm1 US gal
Chloride CI 2.4 40 maximum
SO. 5.9 100 maximum
Total Water Hardness
10 170 maximum Total Solids
20 340 maximum Total Solids
20 340 maximum Acidity
5.5 pH to 9.0 pH For a water analysis, consult one of the following organizations:
1. The Caterpillar Laboratory for an SOS Analysis 2. The LOCC Corporation
3. Local water department 4. Agricultural agent
5. Independent laboratory
Coolant additives help in the following ways: • Preventing rust from forming
• Preventing scale and mineral deposits from forming
• Protecting metals from corroding • Preventing cavitation of the liner
• Preventing coolant from foaming Many additives are depleted during engine operation and these additives need to be
replaced. This can be done through the addition of Supplemental Coolant Additives SCA to Diesel Engine AntifreezeCoolant DEAC or by adding 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. This can cause a gel compound to
form in the radiator. An overconcentration of additives can produce deposits on water pump seals that can cause water pump seal leakage. A low concentration of additives
can produce the following problems:
1. Pitting 2. Cavitation erosion
3. Rust 4. Scale
Glycol in the coolant provides anti-boil protection and freeze protection. Glycol in the coolant prevents water pump cavitation. Glycol in the coolant also reduces cylinder
liner pitting. For optimum performance, Caterpillar recommends a solution that contains a 1:1 mixture of water and of glycol.
Note: Caterpillar engines with air-to-air aftercooling require a minimum of 30 percent glycol in order to prevent water pump cavitation.
Most conventional heavy-duty coolantantifreezes use ethylene glycol. Propylene glycol may also be used. In a mixture that is 50 percent water, ethylene glycol and
propylene glycol have similar properties that are relative to the following elements: heat transfer, freeze protection, control of corrosion and compatibility of the seal.
Check the glycol level of the coolant system with the 1U - 7298 Coolant Tester Group °C or with the 1U-7297 Coolant Tester Group °F. Tables 13 and 14 define the
freeze protection for ethylene glycol and for propylene glycol.
TORQUES FOR BOLTS AND NUTS
The following tables give general torques for metric bolts, nuts, and taperlock studs of Grade 8.8.
The material strength identification is usually shown on the bolt head by numbers 8.8, 10.9, etc.