Coolant is important in your equipment’s cooling systems to prevent freezing, corrosion, cavitation and rust. A periodic coolant analysis can provide important information about the health of your machine.
What’s in coolant?
Nearly all heavy-duty antifreeze is about 95% ethylene glycol and 5% water and additives. About 1% of all antifreeze sold is made from propylene glycol, an alternative to ethylene glycol which is less toxic, but more expensive. By mixing glycol with various ratios of water, coolant is created. Typically, coolant is 30 – 50% glycol.
Formulations differ with the additive package that’s blended into the ethylene glycol. All of these additives fight rust, scale and corrosion but may have different chemical compositions. In diesel engines the additives also protect wet cylinder sleeves from cavitation.
What to look for when buying coolant
- Make sure the coolant you purchase for your diesel engines states that it complies with ASTM standard D-6210 on the package.
- Deionized water is preferred and the coolant should be prediluted, so there is no need to add water.
- Pick an antifreeze type, avoid mixing it with other types, and follow the maintenance recommendations suggested for that coolant.
Maintenance Recommendations
- Periodic visual test
Check color—should be clear, indicating no rust is present, and correct, showing that it has not mixed with another antifreeze type. - Test additive concentrations with a coolant analysis test by taking a sample and submitting it for analysis.
The recommended interval for testing is 1,000 hours. - Sample strips are available to test additive concentrations yourself. Using paper chemically sensitive test strips, you can see problems from color changes which indicate freeze/boil point (glycol content) nitrite (or nitrite/molybdate) levels and, in some instances, pH.