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The coolant provides a medium for heat transfer and controls the internal temperature of the engine during operation. In an engine having proper coolant flow, some of the heat of combustion is conveyed through the cylinder walls and the cylinder head into the coolant. Without adequate coolant, normal heat transfer cannot take place within the engine, and engine temperature rapidly rises. Therefore, coolant must be carefully selected and properly maintained. ‪

The following terms are used throughout this section and must be understood. ‪

  • Coolant - The fluid mixture circulating in the engine cooling system.
  • IEG - Full strength (non-diluted) Inhibited Ethylene Glycol meeting applicable heavy-duty formulation specifications.
  • IPG - Full strength (non-diluted) Inhibited Propylene Glycol meeting applicable heavy-duty formulation specifications.
  • SCA - Supplemental Coolant Additives. Used to prevent corrosion, cavitation, and the formation of deposits.
  • Initial fill - Any time the cooling system is empty, then filled with new coolant.
  • Precharged IEG - Also referred to as a - fully formulated IEG. Contains the proper amount of SCA. Additional SCA must not be used with a precharged IEG at initial fill.
  • Precharged IPG - Also referred to as a - fully formulated IPG. Contains the proper amount of SCA. Additional SCA must not be used with a precharged IPG at initial fill.
  • Dropout - Sludge or deposit formation in or on cooling system components.

Using a coolant with the appropriate concentrations of SCA is one of the most important aspects of quality engine maintenance. To achieve the chemical balance needed to protect a cooling system, certain coolant basics must be understood. ‪

This section provides the directions and information required to ensure cooling system protection. These recommendations are general rules and reflect the current technology. Specific concerns not covered should be addressed to your local Detroit Diesel representative. ‪

The coolant must meet the following basic requirements: ‪

  • Provide an adequate heat transfer medium.
  • Protect against cavitation damage.
  • Provide a corrosion/erosion-resistant environment.
  • Prevent formation of scale or sludge deposits.
  • Be compatible with cooling system hose and seal materials.
  • Provide adequate freeze protection.

A properly maintained coolant can be used for two years, 321,868 km (200,000 miles), or 4000 hours, whichever comes first. At this time the cooling system must be drained, thoroughly cleaned and filled with new coolant. ‪

To achieve these requirements, coolants are mixtures of good quality water, SCA and often an IEG or IPG for freeze protection. The rest of this bulletin will describe the requirements and usage of the water, SCA, IEG, and IPG. ‪


Water is the best practical medium for heat transfer. However, water alone can cause corrosion and inherently contains minerals that can produce scale deposits on internal cooling system surfaces. Chlorides, sulfates, magnesium, and calcium dissolved in the water can cause scale deposits, sludge deposits and/or corrosion. ‪

Distilled or deionized water is preferred to minimize the adverse effects of minerals in water. The maximum allowable limits for minerals in water are listed in Table . The procedure for evaluating the quality of water is shown in the next illustration. See Figure 20868 . ‪


Limit - ppm

Limit - grains per gallon

Chlorides ‪

40 ‪

2.5 ‪

Sulfates ‪

100 ‪

5.8 ‪

Total dissolved solids ‪

340 ‪

20 ‪

Total Hardness: Magnesium & Calcium ‪

170 ‪

10 ‪

Table Maximum Allowable Limits for Minerals in Water

Figure Water Evaluation Procedure

Antifreeze, Inhibited Ethylene Glycol

Ethylene glycol is used for freeze protection of the coolant. IEG, commonly referred to as "antifreeze," also contains chemicals that provide a limited protection against corrosion. The use of an IEG product with a low silicate formulation that meets either the GM 6038-M formulation (GM1899-M performance) or ASTM D 4985 requirements is recommended. ‪

Antifreeze, Inhibited Propylene Glycol

An IPG/water mixture provides freeze protection. ‪

Propylene glycol must meet the performance requirements of ASTM D 4985 and the physical/chemical requirements of ASTM D5216. The maintenance procedures for propylene glycol are the same as for IEG. All references to IEG will also apply to IPG for the engines. ‪

For best overall performance, a 50% concentration of IEG (1/2 IEG, 1/2 water) is recommended. An IEG concentration over 67% (2/3 IEG, 1/3 water) is not recommended because of poor heat transfer, reduced freeze protection, and possible silicate dropout. An IEG concentration below 33% (1/3 IEG, 2/3 water) offers little freeze or corrosion protection and is not recommended ( See Figure 20870 , See Figure 20871 , and See Figure 20869 ). ‪

IEG coolants require the addition of SCA to provide cooling system corrosion and deposit protection. The SCA added should match the chemistry of the additive package included in the coolant. If this precaution is not observed, coolant monitoring can become difficult, making overinhibiting more likely. IEG formulations available in the market may contain from zero to the full amount of the required SCA. A basic IEG with no SCA must have additional SCA added at the time of initial fill. A Fully Formulated or Precharged IEG such as Detroit Diesel Power Cool already contains the required SCA ( listed in Table ). Over concentration will result if SCAs are added to a fully formulated IEG coolant at the time of initial fill. This can result in solids dropout and the formation of deposits. ‪

Power Cool - DDC Part Number


23512138 ‪

1 gallon ‪

23512139 ‪

55 gallons ‪

23512140 ‪

bulk ‪

Table Power Cool Fully Formulated/Precharged IEG

Figure IPG Boiling Point

Figure IPG Freezing Point

Figure Coolant Freezing and Boiling Temperature vs. Inhibited Ethylene Glycol Concentration (Sea Level)

Coolants Not Recommended

Methyl alcohol-based antifreeze should not be used because of its effect on the non-metallic components of the cooling system and its low boiling point. Similarly, methoxy propanol-based antifreeze should not be used because it is not compatible with fluoroelastomer seals found in the cooling system. Glycol-based coolants formulated for heating/ventilation/air conditioning (HVAC) should not be used. These coolants generally contain high levels of phosphates, which can deposit on hot internal engine surfaces and reduce heat transfer. ‪

Supplemental Coolant Additive

SCAs provide protection for the cooling system components. The coolant must have the proper concentration of SCAs. Detroit Diesel Maintenance products are recommended. ‪


Excessive amounts of chemicals in the engine coolant can cause a gel-type or crystalline deposit that reduces heat transfer and coolant flow. The deposit, called dropout takes the color of the coolant when wet, but appears as a white powder when dry. It can pick up solid particles in the coolant and become gritty, causing excessive wear of water pump seals and other cooling system components. The wet gel can be removed by non-acid (alkali) type heavy-duty cleaner, Detroit Diesel Maintenance Product cleaner DD-2001 (sodium nitrite/sodium tetraborate). If the gel is allowed to dry, it is necessary to disassemble the engine and clean with a caustic solution or mechanically clean individual components. ‪

The proper application of SCA will provide: ‪

  • A pH control to prevent corrosion.
  • Water-softening to deter formation of mineral deposits.
  • Cavitation protection to reduce the effects of cavitation.

The proper dosage for initial cooling system fill is listed in Table . Maintenance cooling system fill is listed in Table , initial coolant inhibitor element size requirements for IPG and IEG plus water coolant mixtures are listed in Table . Coolant inhibitor element size requirements, initial dosage for water-only systems, are listed in Table . The proper maintenance dosages are listed in Table . ‪


Coolant Element


Precharged IEG and Water ‪



IEG and Water ‪

Select Element listed in Table . ‪

3% by Volume, or 1 pint per 4 gallons * ‪

Water only ‪

Select Element listed in Table . ‪

6% by Volume, or 1 quart per 4 gallons * ‪

Table Initial Fill SCA Dosage

Note: * 8 pints = 1 gallon, 4 quarts = 1 gallon, 1 gallon = 3.8 L

Coolant Element


Select element listed in Table

0.6% by Volume or 1 pint per 20 gallons * ‪

Table Maintenance SCA Dosage

Note: * 8 pints = 1 gallon, 1 gallon = 3.8 L

Cooling System Capacity Gallons (L)


DDC Part Number

Nalco Part Number

9-12 (34-45) ‪

1 ‪

23508426 ‪

DDF-3000.12 ‪

13-16 (49-61) ‪

1 ‪

23507189 ‪

DDF-60.16 ‪

Table Coolant Inhibitor Element Size Requirements-Initial Fill Dosage for IEG or IPG plus Water Coolant Mixtures

Cooling System Capacity Gallons (L)

SCA Element Quantity

Detroit Diesel SCA Element Part Number

Additional SCA Liquid Required

Nalco Element Part Number

10 (38) ‪

1 ‪

23507189 ‪

DDF-60.12 ‪

None ‪

Table Coolant Inhibitor Element Size Requirements-Initial Dosage for Water-Only System

Cooling System Capacity, Gallons (L)


DDC Part Number

Nalco Part Number

9-12 (34-45) ‪

1 ‪

23507545 ‪

DDF-3000 ‪

13-16 (49-61) ‪

1 ‪

23507545 ‪

DDF-3000 ‪

Table Coolant Inhibitor Element Size Requirements-Maintenance Dosage for IEG, IPG, Precharged, and Water-Only Coolant Mixture

The concentration of SCA will gradually deplete during normal engine operation. Check the SCA concentration at the regular intervals listed in Table . Additional SCA must be added to the coolant when it becomes depleted below a specified level ( listed in Table ). Maintenance dosage of SCA must only be added if nitrite concentration is less than 800 ppm. If nitrite concentration is greater than 800 ppm, do not add additional SCA. ‪

Service Application

Inhibitor Test Interval

On-highway Trucks and Motor Coaches ‪

15,000 miles (24,000 km) ‪

Table Required Coolant Inhibitor Test Intervals


Minimum SCA ppm

Maximum SCA ppm

Boron (B) ‪

1,000 ‪

1,500 ‪

Nitrite (NO 2 ) ‪

800 ‪

2,400 ‪

Nitrates (NO 3 ) ‪

1,000 ‪

2,000 ‪

Silicon (Si) ‪

50 ‪

250 ‪

Phosphorus (P) ‪

0 ‪

500 ‪

pH ‪

8.5 ‪

10.5 ‪

SCA Limits with GM6038-M or ASTM-D 4985 (50/50 Coolant/Water Mixture)

Soluble Oils

Soluble oil additives are not approved for use in the cooling systems. A small amount of oil adversely affects heat transfer. A 1.25% concentration of soluble oil increases the fire deck temperature 6%. A 2.50% concentration increases the fire deck temperature 15%. ‪


Chromate additives are not approved for use in cooling systems. Chromate additives can form chromium hydroxide, commonly called green slime. This, in turn, can result in engine damage due to poor heat transfer. Cooling systems operated with chromate-inhibited coolant must be chemically cleaned with Nalcool 2015 cooling system cleaner and conditioner (or equivalent sulfamic acid/sodium carbonate cleaner) and flushed. ‪

Some coolant filter elements with magnesium internal support plates have caused engine damage. The coolant dissolves the magnesium and deposits it on the hot zones of the engine where heat transfer is most critical. The use of elements with these plates is not approved. ‪

Detroit Diesel Cooling System Maintenance Products

Detroit Diesel Maintenance Products SCA are water-soluble chemical compounds. These products are available in coolant filter elements, liquid packages, and a fully formulated IEG. ‪

Coolant Filter Elements

Replaceable coolant filter elements (spin-on canisters) are available in various sizes suitable for cooling systems of varying capacity. Selection of the proper element size is vital when precharging the coolant system at initial fill and at maintenance intervals. ‪

Note: A fully formulated IEG or IPG must NOT have SCA added at initial fill.

The need for maintenance elements is determined by the results of the SCA concentration test performed at each cooling system service interval. ‪

Supplemental Coolant Additive Test Procedures

Nitrite concentration is an indication of the SCA concentration in the coolant. Nitrite test kits and test strips are commercially available. The coolant must be tested for required inhibitor levels at the intervals listed in Table . SCA levels must be within the ranges listed in Table . ‪

Liquid Supplemental Coolant Additive

Detroit Diesel Cooling System Maintenance Procedures SCA and Cleaners are available in liquid form and are listed in Table . ‪



DDC Part No.

Nalcool 2000 - Liquid SCA* ‪

1 pint (12 per case) ‪

23507858 ‪

Nalcool 2000 - Liquid SCA* ‪

half gallon (6 per case) ‪

23507859 ‪

Nalcool 2000 - Liquid SCA* ‪

5 gallons ‪

23507860 ‪

Nalcool 2000 - Liquid SCA* ‪

55 gallons ‪

23507861 ‪

Nalcool 3000 - Liquid SCA* ‪

1 pint (12 per case) ‪

23507854 ‪

Nalcool 3000 - Liquid SCA* ‪

half gallon (6 per case) ‪

23507855 ‪

Nalcool 3000 - Liquid SCA* ‪

5 gallons ‪

23507856 ‪

Nalcool 3000 - Liquid SCA* ‪

55 gallons ‪

23507857 ‪

Nalprep 2001 ON-LINE CLEANER* ‪

half gallon (6 per case) ‪

23507862 ‪

Nalprep 2001 ON-LINE CLEANER* ‪

5 gallons ‪

23507863 ‪

Nalprep 2001 ON-LINE CLEANER* ‪

55 gallons ‪

23507864 ‪

Nalcool 2015, Twin Pac, Dry, Chemical Cleaner/Conditioner* ‪

2 per case ‪

23507867 ‪

Table Liquid SCA and Additional Coolant Treatment Products

Note: * Nalcool 3000 is more compatible with hard water than Nalcool 2000. Use Nalprep 2001 for light deposits. Use Nalprep 2015 for heavy deposits or scale. Nalcool and Nalprep are licensed trademarks of the Penray Companies.

Test Kit Procedures

Use Detroit Diesel Power Trac 2-Way Coolant Test Strips (part number 23515917) to measure nitrite and glycol concentrations. Cavitation/corrosion protection is indicated on the strip by the level of nitrite concentration. ‪


Do not use Detroit Diesel Power Cool test strips to determine the inhibitor levels of coolant with non-DDC approved additive packages. Incompatible chemicals and variance in inhibitor levels in the additive packages may cause inaccurate interpretation of test strip readings. This can lead to under-inhibiting the coolant, which may result in cavitation erosion. ‪

Freeze/boilover protection is determined by glycol concentration. Use the test strips as follows: ‪

  1. Dip the strip into coolant for one second. Remove and shake briskly to eliminate excess fluid.
  2. Immediately compare end pad (% glycol) to the color chart.
  3. Sixty seconds (one minute) after dipping, compare the nitrite pad.

For best results make the tests while the coolant is between 50 and 140F (10 - 60C). Wait at least 60, but not longer than 75 seconds before reading the nitrite level. Promptly replace and tighten container cap after each use. Discard unused strips if they have turned light pink or tan. ‪

A factory coolant analysis program is also available through authorized Detroit Diesel service outlets under part number 23508774. ‪

Summary of Coolant Recommendations

Coolant recommendations may be summarized as follows: ‪

Note: Propylene glycol meeting ASTM D 4985, and ASTM D 5216 is approved for use.

  1. Always maintain the engine coolant to meet Detroit Diesel specifications.
  2. Only use water that meets Detroit Diesel specifications. Distilled or deionized water is preferred.
  3. The proper dosage of SCA must be included in the coolant at initial fill.

    This dosage can be either included in part or entirely in the IEG used, or it may need to be added. Dosage is also dependent on whether water or IEG is used. ‪

  4. Maintain the SCA to the prescribed concentration. Test the nitrite concentration by using a titration kit or Detroit Diesel 2-Way Coolant Test Strips. Add SCA only if the nitrite concentration is below 800 ppm.

    Do not use another manufacturer's test kit to measure the SCA concentration of Detroit Diesel Maintenance Products. ‪

  5. Pre-mix coolant makeup solutions at the proper concentration before adding to the coolant system.
  6. Where antifreeze/boilover protection is required, use only ethylene glycol coolant (low silicate formulation) meeting GM 6038-M, GM 1899-M, or ASTM D 4985. Propylene glycol meeting ASTM D 4985, and ASTM D 5216 is also approved for use.
  7. Always maintain proper coolant level.
  8. A properly maintained cooling system can be operated for up to two years, 200,000 miles (320,000 km) or 4000 hours, whichever comes first. At this interval the cooling system must be thoroughly cleaned and the coolant replaced.
  9. Do not use the following in Detroit Diesel engine cooling systems:
    • Soluble oil
    • Chromate SCA
    • Methoxy propanol-base coolant
    • Methyl alcohol-base coolant
    • Sealer additives or coolant containing sealer additives
    • HVAC coolant