LO 11-8 Outline maintenance procedures and identify tools and methods used to perform maintenance on a diesel engine cooling system

1.12. Testing Coolant Nitrite or Diesel Coolant Additive/Supplemental Coolant Additive Levels

Testing Coolant Nitrite or Diesel Coolant Additive/Supplemental Coolant Additive Levels
Nitrite is the most important additive used in diesel coolant because it prevents cavitation damage in the cooling system. Nitrite is one of the ingredients present in DCA and SCA coolant conditioner packages. Coolant filters also have a specific level of nitrite that requires matching a coolant filter with the cooling system maintenance requirements. In engines that use conventional type I antifreeze, nitrite levels should be checked at every oil change. For engines using ELC, nitrite levels should be checked once or twice a year. Different nitrite levels are required depending on the antifreeze formulation used. Type I requires 3–5% nitrite levels, but long-life formulations require substantially less. A coolant test strip that contains at least three kinds of chemically treated testing pads should be used: one for antifreeze concentration, another for nitrite levels, and another for pH. Additional pads can be found on test strips for testing other corrosion inhibitors. To test coolant nitrite or DCA/SCA levels, follow the steps in Skill Drill 11-4.