Coolant is normally composed of three elements:
- Water
- Additives
- Glycol
Water
| NOTICE |
|---|
Never use water alone without Supplemental Coolant Additive (SCA's) 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 Water Quality Limits | ||
| Water Property | PPM mg per liter Max |
grains/US gal Max |
| Chloride (1) (Cl) | 40 | 2.4 |
| Sulfate (2) (SO4) | 100 | 5.9 |
| Total Water Hardness (3) | 170 | 10 |
| Total Solids (4) | 340 | 20 |
| Acidity (5) | 5.5 pH to 9.0 pH | |
| ( 1 ) | See "ASTM D512b", "ASTM D512d" or"ASTM D4327". |
| ( 2 ) | See "ASTM D516b"or "ASTM D516d". |
| ( 3 ) | See "ASTM D1126". |
| ( 4 ) | See "ASTM D1888a". |
| ( 5 ) | See "ASTM D1293". |
For a water analysis, consult one of the following organizations:
- The Caterpillar Laboratory for an S·O·S Analysis
- The LOCC Corporation
- Local water department
- Agricultural agent
- Independent laboratory
Additives
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 Antifreeze/Coolant (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:
- Pitting
- Cavitation erosion
- Rust
- Scale
- Foaming
Glycol
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 coolant/antifreezes 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 2 and 3 define the freeze protection for ethylene glycol and for propylene glycol.
| Ethylene Glycol | ||
| Concentration | Freeze Protection | Anti-Boil Protection |
| 50 Percent | -36°C (-33°F) |
106°C (223°F) |
| 60 Percent | -51°C (-60°F) |
111°C (232°F) |
| Propylene Glycol | ||
| Concentration | Freeze Protection | Anti-Boil Protection |
| 50 Percent | -29°C (-20°F) |
106°C (223°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 freeze or anti-boil protection. |