LO 11-4 Classify and describe the types, functions, and applications of diesel engine coolant

Ethylene Glycol Antifreeze Base

Coolant has evolved considerably since the early days of automotive technology. In the past, coolant included mixtures of alcohol and water as well as water mixed with honey and soluble oils. In the 1940s, ethylene glycol was developed to provide both freeze and boil-over protection. When initially manufactured, ethylene glycol is a clear, colorless, syrupy fluid. Green dye is added for identification. One of the most significant reasons ethylene glycol is dyed is to clearly distinguish it from other coolants, as it is extremely poisonous. If ingested, 4 oz (113 g) of ethylene glycol will cause fatal kidney failure in humans after a couple of days. Many animals die from antifreeze poisoning every year because they are attracted to the antifreeze’s sweet odor and taste. Embitterment may be added to antifreeze by some producers to discourage animals from drinking antifreeze leaking from engines. Ethylene glycol–based coolants must be recovered and recycled to prevent environmental contamination. TMC categories for ethylene glycol are types I, II, and IV. Types V and VI are not designated as having any specific type of antifreeze base.