KEEPING COOLANT
IN SOUTHERN REGIONS, THE COLDER NIGHTS REMIND MANY PEOPLE TO CHECK THEIR ANTI-FREEZE, EVEN THOUGH THE COOLING SYSTEM HAS A YEAR-ROUND JOB TO DO. LET’S CHECK IN ON THE COOLING SYSTEM
T
he coolant used to protect engines is typically a 50/50 mix of water and ethylene (or propylene) glycol. Why a mix? Water is an excellent medium for removing heat, but it provides no protection from the build up of rust or corrosion in the cooling system passageways or components. It also has a limited operating range, with a freeze point of 0°C and boiling point of 100°C. The development of pressurised cooling systems during World War II raised the upper limit a bit, but it did nothing to lower the bottom end, so glycol had to be added to the water to prevent it from freezing. Ethylene glycol has a freeze point of -12°C and a boiling point of 196°C. The high end is fine but the low end is still short on freeze protection when used in extremely cold climates. Alone, it is also less efficient than water at absorbing heat — about 10-20 per cent less efficient. So, while it appears a better choice than pure water alone (and it is), the use of coolant alone is still lacking and no better as an option. However, when mixed in a 50/50 proportion, the resulting cooling fluid has a freeze point of -36°C and, with a 14 psi radiator cap installed, a boiling point of 129°C. A mixture range of 40-60 percent will still provide sufficient heat transfer, while maintaining freeze protection. What’s the best way to test the mixture ratio? Manufacturers agree that the use of a refractometer is the best way to test, with coolant test strips coming in a close second. The hydrometers of old are not accurate enough to test the coolant mixture and should be avoided.
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Auto Channel Issue #47 June 2022
The best way to check the mixture ratio is with a tool called a refractometer. Just be sure to compensate as outlined in the tool’s manual prior to taking your reading
