Tips for Cooling System Maintenance
by Ed Eckert, CLS
Diagnostics Manager

Maintaining the coolant in an engine is critical to its reliability and performance. The bullet points below offer suggestions and tips to maintaining a healthy cooling system.

  • Always use 50/50 premix and never concentrate whenever possible – this ensures proper source water is being used.
  • If possible, use distilled water when mixing with concentrate. If using tap water, have the water tested or go online to look up the local water municipality’s water quality report. Using improper source water can lead to elevated levels of sulfates and chlorides or water hardness. Sulfates and chlorides are corrosive to the system, and water hardness can produce excessive scale build-up. Scale build-up will impede proper heat transfer.
  • If using an auto mixer, submit a sample coming directly from the unit to ensure the equipment is working properly and dispensing 50/50.
  • For proper coolant management, ensure engines that are out in the field have a container or two of the same coolant that is used in the shop. This will eliminate the possibility of mixing two different coolant types if a top-up is needed and potentially reducing the life of the coolant.
  • Using nitrite free coolant, but the nitrites are showing up on your report? This is an indication of mixing with another coolant type which contains nitrites, or that an SCA filter is installed on the engine. Some engine manufacturers require the use of Nitrite Free (NF) coolants due to aluminum components in the engine and cooling system. Nitrites will react with aluminum initiating surface corrosion. If you have ever noticed an ammonia odor coming from the cooling system, it’s the nitrites reacting with the aluminum.
  • If using ELC coolants, DO NOT use a chemical filter that contains SCA (Nitrites). Not only will the chemistry of the ELC be compromised, but SCA’s form a sacrificial coating on the metal surfaces that will reduce the heat transfer properties of the coolant. Think of being hot then throwing a blanket around yourself, you’re only going to get hotter. By removing the blanket of SCA’s the cooling system will operate more efficiently. Make sure you are using a particulate filter only.
  • Looking at the pH level can indicate a failed EGR cooler. Did you know you can tell if an engine has an EGR leak just by looking at the pH? Exhaust gases entering the cooling system will considerably lower the pH of the coolant. By routine monitoring of the coolants pH level, noticing a sudden drop in pH could mean the engine has a leak in the EGR cooler.
  • Never return used coolant back into the engine after a repair. Depending on the repair, the used coolant may be corrosive, contain excessive particulate contamination or is degraded, which will cause harm to the newly repaired engine.
  • Use your oil analysis results to identify that an engine may be over-heating, and the need to check the cooling system. Elevated viscosity and increased soft metals (lead, copper, tin) are an indication the engine is running hot. Insufficient water and excessive glycol concentration can do this. Check the radiator cap for integrity. If the system is not tight, water will boil out of the coolant.