Field Testing Coolants
It is possible to test coolant in the shop to find obvious and potentially serious problems. The two most common problems are coolant dilution with water (or sometimes failure to dilute), and low liner protection in diesels. The use of a refractometer is recommended for freeze point (antifreeze mix) testing, and nitrite test strips are well proven as valuable screening tools to check SCA concentrations.
Field testing engine coolant is possible with refractometers and test strips to screen for major problems.
Hydrometers sold for antifreeze testing have been reviewed by ASTM, and the performance thereof was so poor that ASTM has withdrawn the hydrometer test method from the books. In its place, a method employing a refractometer has been established. This is a good method, and definitely the method of choice check the coolant freeze point.
Diesel engines often use coolant that contains nitrite or nitrite and molybdate to protect wet sleeve liners. The coolant companies have developed test strips appropriate for their coolant technologies. It is a valuable screening tool, but the technician must use a test strip appropriate for the coolant that he is testing. Using the wrong kind of test strip can result in misinterpretation of the coolant condition, resulting in incorrect maintenance decisions.
Any problems identified by a field test method should be confirmed by sending a coolant sample to a qualified coolant testing lab.
