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Engine coolants are a combination of three chemical components: ethylene glycol (antifreeze), inhibiting coolant additives, and quality water.
Coolant Specifications
Some products, including John Deere John Deere COOL-GARD Prediluted Coolant, are fully formulated coolants that contain all three components in their correct concentrations. Do not add an initial charge of supplemental coolant additives to these fully formulated products.
Some coolant concentrates, including John Deere COOL-GARD Coolant Concentrate, contain both ethylene glycol antifreeze and inhibiting coolant additives. Mix these products and quality water, but do not add an initial charge of supplemental coolant additives.
Coolants meeting ASTM D5345 (prediluted coolant) or ASTM D4985 (coolant concentrate) require an initial charge of supplemental coolant additives.
Replenish Coolant Additives
The concentration of coolant additives is gradually depleted during engine operation. Periodic replenishment of inhibitors is required, even when John Deere COOL-GARD is used. Follow the recommendations in this manual for the use of supplemental coolant additives.
Why Use Supplemental Coolant Additives?
Operating without proper coolant additives will result in increased corrosion, cylinder liner erosion and pitting, and other damage to the engine and cooling system. A simple mixture of ethylene glycol and water will not give adequate protection.
Use of supplemental coolant additives reduces corrosion, erosion, and pitting. These chemicals reduce the number of vapor bubbles in the coolant and
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help form a protective film on cylinder liner surfaces. This film acts as a barrier against the harmful effects of collapsing vapor bubbles.
Avoid Automotive-Type Coolants
Never use automotive-type coolants (such as those meeting ASTM D3306 or ASTM D4656). These coolants do not contain the correct additives to protect heavy-duty diesel engines. They often contain a high concentration of silicates and may damage the engine or cooling system.
Water Quality
Water quality is important to the performance of the cooling system. Distilled, deionized, or demineralized water is recommended for mixing with ethylene glycol base engine coolant concentrate. All water used in the cooling system should meet the following minimum specifications for quality:
| Chlorides |
<40 mg/L |
| Sulfates |
<100 mg/L |
| Total Dissolved Solids |
<340 mg/L |
| Total Hardness |
<170 mg/L |
| pH |
5.5 to 9.0 |
Freeze Protection
The relative concentrations of ethylene glycol and water in the engine coolant determine its freeze protection limit.
| Ethylene Glycol |
Freeze Protection Limit |
| 40% |
-24°C (-12°F) |
| 50% |
-37°C (-34°F) |
| 60% |
-52°C (-62°F) |
DO NOT use a coolant-water mixture greater than 60% ethylene glycol.
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