1. Classifications of Coolant

1.5. Glycerin-Based Antifreeze

LO 11-04: Classify and describe the types, functions, and applications of diesel engine coolant.

 

Glycerin-Based Antifreeze
Glycerin is another nontoxic base for antifreeze. Glycerin was used as a heat transfer agent in antifreeze formulations as early as the 1920s but was eventually displaced by ethylene glycol. Interest in this antifreeze base has been revived due to the biofuel industry, which produces huge amounts of glycerin as a byproduct of biofuel production. Glycerin, which is also sometimes called propanetriol or glycerol , has a number of distinct advantages, including:

  • Close to neutral pH
  • Inexpensive, or at least cost-competitive, price point
  • Environmentally friendly, nontoxic properties
  • Support of the renewable fuel industry
  • Compatibility with most cooling system material

Cummins currently produces a glycerin-based antifreeze, Compleat™, that meets the recently developed ASTM International (formerly known as the American Society for Testing Materials) standard for the latest antifreeze technology. There is currently no TMC designation for this type of antifreeze.

The primary disadvantage of glycerin is that its freeze- protection temperature is high in comparison to that of ethylene glycol. Diluted to a 30/70 water-to-glycerin concentration, glycerin can provide freeze protection only to −36° F (−37.8° C). At that concentration and freeze-protection point, glycerin-based coolant is not able to remove as much heat as a mixture with a higher amount of water and the same freeze protection. The different density of the antifreeze also requires new test instruments, such as a purpose-made refractometer, to evaluate freeze protection. Test strips presently used for the evaluation of glycol-based coolant conditions in service are not usable for glycerin-based coolants.

  Technicians Tip  
  Understanding which type of antifreeze to use can be confusing to even the most well-informed technician. The various bases, chemical formulations, and colors of antifreeze available today are chosen primarily for their compatibility with materials in the cooling system and environmental concerns. The wrong antifreeze can cause severe deterioration in the cooling system, gaskets, and cylinder head gaskets as well as cause damage to coolant hoses Figure 31. To avoid problems and confusion, always check the manufacturer’s recommendations for antifreeze noted on surge tank decals or service bulletins. In emergencies, no more than 5% contamination is permissible by most manufacturers.  

 

  Fig11_31

FIGURE 11-31: Note that this coolant is not blue but contains purple type II antifreeze with organic acid technology additives but no phosphate. Both Detroit Diesel and other European engine manufacturers do not want dissolved solids, such as phosphates, in their engine coolant.

   Fig11_32

FIGURE 11-32: This Kenworth truck chassis, with an electric drive propulsion system, has a fuel cell. It is critical that only the correct coolant and distilled or deionized water is added to the cooling system.

  

 

  Technicians Tip  
  In electric vehicles with fuel cells, it is critical that only deionized or distilled water and the correct antifreeze formulation is added to the fuel cell cooling system. Any other coolant, particularly tap water with trace minerals, metals, and chlorine, form coolant electrolytes and make it electrically conductive. Electrically conductive coolant will cause severe and potentially catastrophic damage to fuel cells Figure 32.  

 

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