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The cooling system operates under pressure which is controlled by the radiator pressure cap. Removing the cap while the system is hot may allow the escape of hot coolant and steam, causing serious burns. Before you remove the radiator cap, allow the system to cool. Use a thick cloth and turn the radiator cap slowly to the first stop to allow pressure to escape before fully removing the cap. Avoid contact with coolant. |
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Every attempt is made to provide accurate, up-to-date information. By the use of this document, you agree that Caterpillar Inc. is not responsible for errors or omissions. |
The information that is provided is the latest recommendations for the Cat diesel engines that are covered by this Special Publication. This information supersedes all previous recommendations which have been published for the Cat diesel engines that are covered by this Special Publication. Special fluids may be required for some engines. Continue to use these special products. Refer to the applicable Operation and Maintenance Manual.
This publication is a supplement to the Operation and Maintenance Manual. This publication does not replace the engine Operation and Maintenance Manual.
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These recommendations are subject to change without notice. Consult your local Cat dealer for the most up to date recommendations. |
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In order to avoid potential damage to your Cat machine and/or Cat engine, only purchase Cat fluids and Cat filters through your Cat dealer or Cat authorized outlets. For a list of authorized Cat parts outlets in your area, consult your Cat dealer. If you purchase what appear to be Cat fluids and/or Cat filters through other outlets/sources, you are at a very high risk of purchasing counterfeit (“look-alike”) products. Counterfeit or “look-alike” products may visually appear the same as the original Cat product, but the product performance and internal quality will typically be very low. Counterfeit or “look-alike” products have a very high likelihood of causing and/or allowing engine and/or machine compartment damage. |
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Commercial products that make generic claims of meeting “Cat” requirements without listing the specific Cat recommendations and requirements that are met may not provide acceptable performance. Commercial products may cause reduced engine and/or machine fluid compartment life. Refer to this Special Publication and refer to product specific Operation and Maintenance Manual for Cat fluids recommendations and requirements. |
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Never add coolant to an overheated engine. Engine damage could result. Allow the engine to cool first. |
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If the engine is to be stored in, or shipped to an area with below freezing temperatures, the cooling system must be either protected to the lowest outside temperature or drained completely in order to prevent damage caused by freezing coolant. |
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Never operate an engine without water temperature regulators in the cooling system. Water temperature regulators help to maintain the engine coolant at the proper operating temperature. Cooling system problems can develop without water temperature regulators. If you operate the engine without the regulator, some coolant bypasses the radiator. This may cause overheating. |
Note: Refer to the specific engine Operation and Maintenance Manual, "Maintenance Interval Schedule" for the correct interval for the replacement of the thermostat.
Refer to Special Instruction, SEBD0518, "Know Your Cooling System" for more detailed information.
Many engine failures are related to the cooling system. The following problems are related to cooling system failures:
- Overheating
- Leakage of the water pump
- Plugged radiators or heat exchangers
- Pitting of the cylinder liners
These failures can be avoided with proper cooling system maintenance. Cooling system maintenance is as important as maintenance of the fuel system and the lubrication system. Quality of the coolant is as important as the quality of the fuel and the lubricating oil.
A coolant that is ready to use in the engine can also be referred to as “finished coolant”. A finished coolant is a coolant that has been diluted with appropriate amount of acceptable quality water.
Coolant is normally composed of the following elements:
- water
- additives
- glycol
- Embitterment: in coolants containing ethylene glycol to make the coolant taste bad.
Technical information for each of the coolant elements is provided in this Special Publication.
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Never use water alone as a coolant. Water alone is corrosive at engine operating temperatures. In addition, water alone does not provide adequate protection against boiling or freezing. |
Note: In glycol-based coolants, Cat strongly recommends a minimum of 30 percent glycol in diesel engine cooling systems, with a minimum of 50 percent glycol recommended. Use only glycol-based coolants that meet one or more of the coolant specifications that are defined as preferred or acceptable in this Special Publication and that also comply with any additional requirements that are stated in this Special Publication (that is, chemical composition, the use of SCA, the use of Extender). Refer to the Operation and Maintenance Manual for your engine for any exceptions, and refer to Table 1 for marine engine exceptions.
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All Cat engines that are equipped with a Cat NOx Reduction System require a minimum of 50 percent glycol to help prevent cavitation damage and boiling of the engine coolant. These engines include Tier 4 engines. |
| Special Requirements(1) | |
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| Cat 3618 engine model | Water based ELI is recommended. Water based SCA is acceptable. Glycol-based coolants are NOT allowed. |
| (1) | Water based ELI and SCA are not recommended for use in applications that require freeze protection. Water based coolants are glycol-free. |
C7-C32 heat exchanger cooled marine engines require a minimum of 30 percent glycol to prevent cavitation of cooling system components, with a minimum of 50 percent glycol recommended.
Note: For engines that require a maximum of 20% glycol, make sure that the amount of additive in the final mix is appropriate. Example of mixing a 20% glycol solution is given in Table 2.
| Example of Mixing Up a 20% Glycol Coolant (1) | |||
| Total Volume of the Cooling System | Add the Following: | ||
| ELC Concentrate | ELI Concentrate | Water | |
| 10 Gallons | 2 Gallons | 0.5 Gallons | 7.5 Gallons |
| (1) | Volumes can also be in liters as long as all the volume units are consistent |
Water in the water/glycol coolants is more effective than glycol alone in transferring heat.
Distilled water or deionized water is recommended to add to glycol or to water based coolants in engine cooling systems.
DO NOT use the following types of water in cooling systems: hard water, softened water that has been conditioned with salt and sea water.
If distilled water or deionized water is not available, use water that meets or exceeds the minimum acceptable water requirements that are listed in Table 3.
| Cat Minimum Acceptable Water Requirements | ||||
|---|---|---|---|---|
| Property | Maximum Limit | ASTM Test | ||
| Chloride (Cl) | |
"D512", "D4327" | ||
| Sulfate (SO4) | |
"D516"
"D4327" |
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| Total Hardness | |
"D1126" | ||
| Total Solids | |
"D1888"
"Federal Method 2504B"(1) |
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| Acidity | pH of 5.5 to 9.0 | "D1293" | ||
| (1) | Total dissolved solids dried at |
For a water analysis, consult one of the following sources:
- Cat dealer
- Local water utility company
- Agricultural agent
- Independent laboratory
Periodic analysis of water that is used to add to the coolant is recommended. Water quality can be affected by various factors including malfunctioning purification equipment, earthquakes, and droughts.
Additives help to protect the metal surfaces of the cooling system and can improve coolant performance. A lack of coolant additives, insufficient amounts of additives, or improper additives for the application can cause 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. Additives that can be added:
- ELC Extender to Cat ELC (Extended Life Coolant)
- ELC Extender to Cat ELI (Extended Life Inhibitor)
- Cat SCA (Supplemental Coolant Additive) to Cat DEAC (Diesel Engine Antifreeze/Coolant)
- · Cat SCA to Cat SCA in water finished coolant
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 in the coolant helps to provide protection against the following conditions:
- Boiling
- Freezing
- Water pump cavitation (ATAAC equipped engines)
For optimum performance, Cat recommends a 50 percent by volume of glycol in the finished coolant (also referred to as 1:1 mixture).
Note: Use a mixture that will provide protection against the lowest ambient temperature.
Most conventional heavy-duty coolant/antifreezes use ethylene glycol. Propylene glycol may also be used. In a 50 percent by volume of glycol in the finished coolant, ethylene and propylene glycol provide similar protection against freezing and boiling. Refer to tables 4 and 5.
| Ethylene Glycol Concentration | ||
|---|---|---|
| Concentration | Freeze Protection | Boil Protection(1) |
| 20 Percent | |
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| 50 Percent | |
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| 60 Percent | |
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| (1) | Boiling protection is increased with the use of a pressurized radiator. |
Do not use propylene glycol in concentrations that exceed 50 percent glycol because of the reduced heat transfer capability. Use ethylene glycol in conditions that require additional protection against boiling or freezing. Do not use ethylene glycol in concentrations that exceed 60 percent glycol.
| Propylene Glycol Concentration | ||
|---|---|---|
| Concentration | Freeze Protection | Boil Protection(1) |
| 50 Percent | |
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| (1) | Boiling protection is increased with the use of a pressurized radiator. |
Propylene glycol coolant that is used in the cooling systems for Cat diesel engines must meet ASTM D6210-06, "Fully-Formulated Glycol-Based Engine Coolant for Heavy-Duty Engines". When propylene glycol coolant is used in heavy-duty diesel engines, a regular addition of SCA is required for protection against liner cavitation. Consult your Cat dealer for additional information.
Ethylene or propylene glycols used in cooling systems for Cat diesel engines must meet ASTM E1177-06, "Standard Specification for Engine Coolant Grade Glycol".
Testing the Concentration of Glycol
To check the concentration of glycol, use the 245-5829 Coolant/Battery Tester/Refractometer or 360-0774 refractometer. The tester can be used with ethylene or propylene glycol.
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| Illustration 1 | g01189253 |
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Approximate curve of the freezing point for a typical ethylene glycol solution. | |
| Freeze Protection for Antifreeze Concentrations(1) | |
| Protection to: | Concentration |
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20% glycol
80% water |
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30% glycol
70% water |
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40% glycol
60% water |
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50% glycol
50% water |
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60% glycol
40% water |
| (1) | Ethylene glycol-based antifreeze. |
Alternative products that are used to protect from boiling or freezing of the engine coolant include:
- “1,3 propandiol” (PDO)
- glycerin
- mixtures of these alternative products with glycol
At the time of publication of this document, there currently exists no ASTM, "specifications" for coolants using these chemicals. Until specifications are published and then evaluated by Cat, use of PDO and glycerin or glycerin/glycol coolants are not recommended in Cat cooling systems.
Ethylene glycol is a toxic chemical with a naturally sweet taste. In order to avoid accidental excessive ingestion by humans or animals, coolants may contain embittering agents that make the coolant taste bad. All Cat glycol containing coolants (Cat ELC, Cat DEAC, and Cat NGEC) are embittered. Embittering agents have no beneficial or detrimental effect on coolant performance or characteristics.
Extended Life Coolant (ELC) - A coolant that relies largely on organic inhibitors for corrosion and cavitation protection. Carboxylate is an example of organic corrosion and cavitation inhibitors. Cat ELC and Cat ELI in water are extended life coolants that also include nitrites and molybdates for increased cavitation protection.
- Commercial extended life coolants containing silicate do not meet the additional requirements set in this Special Publication for coolants claiming to meet Cat EC-1 specification.
- Do not use commercial extended life coolants with more than 125 ppm silicon (present in the coolant in the form of silicate)
- Extended life coolants that meet "ASTM D4985-05" or "ASTM D6210-06" may be used at the recommended maximum coolant service life intervals stated in this Special Publication for coolants that meet the ASTM specifications.
Conventional coolant - A coolant that relies largely on inorganic inhibitors for corrosion and cavitation protection. Silicates and nitrites are examples of inorganic inhibitors. Conventional coolants are also referred to as heavy-duty coolants, heavy-duty fully formulated coolants, or traditional coolants. In order to be used in most Cat cooling systems, conventional coolants must meet "ASTM D4985-05" or "ASTM D6210-06". Cat DEAC and Cat SCA in water (also referred to as SCA/Water coolant) are conventional coolants
Supplemental Coolant Additive (SCA) - SCA is a general term for a concentrated inorganic inhibitor package. SCA is used for three different purposes:
- to precharge a new conventional coolant that is not fully Formulated. Cat DEAC is fully formulated and does not require SCA
- to provide corrosion protection in water/SCA cooling systems
- to recharge an in service conventional coolant on a maintenance basis to maintain proper inhibitor levels
Extender - An inhibitor package that is added to extended life coolants, to recharge an in-service coolant. Extenders, typically, only should be added at one half the service life of the coolant.