Improper maintenance of a heavy duty coolant system can create cavitation pitting. If engine metals lack proper protection, the damage can affect the entire coolant system and engine operation.

Improper maintenance of a heavy duty coolant system can create cavitation pitting. If engine metals lack proper protection, the damage can affect the entire coolant system and engine operation.

The wrath of winter’s impact on heavy-duty diesel engines across North America has been thoroughly tested so far this year. Arctic sub-zero temperatures and double-digit wind-chills left many trucks stranded or with incapacitated equipment.

For many of those stranded during the winter cold snap, it was decisions made about what to do (or what not to do) with their antifreeze/coolant systems that may have sealed their fate.

At a glance, coolant maintenance may seem to be as simple as pouring in new coolant. However, given the vast number of new antifreeze/coolant technologies and formulations, making decisions regarding their maintenance is a very serious matter that can potentially affect the bottom line of any fleet. Ask anyone who may have been stranded or stuck in the shop during any brutal winter cold snap.

The primary components of antifreeze, both glycol and water, can freeze; however, a combination of both has the ability to prevent freezing to a lower temperature.

While recognizing glycol levels in antifreeze/coolant is essential to maintaining a properly operating heavy-duty vehicle, it is by no means less of a concern than corrosion within the engine. During extreme temperatures, fleets are not thinking so much about corrosion protection as they are trying to make sure the necessary percent of glycol is correct in their formula. Corrosion protection is a daily concern for the heavy duty engine, and freezing concerns tend to be seasonal.

“A solid practice for antifreeze/coolant maintenance would be to take the opportunity to check the overall effectiveness of coolant while also checking for seasonal freezing protection," says Peter Woyciesjes, worldwide research development and engineering coolants manager for Prestone.

There are three steps for such an inspection:

  1. Test your glycol for freeze-point.
  2. Test it for inhibitors to make sure you’re still getting the correct corrosion protection.
  3. Make sure you’ve got the right volume in your cooling system so you’re not getting air pockets.

“Air entrapment in the engine is a serious problem for any engine,”  Woyciesjes says. “Seasonal cold weather testing is the ideal time to make sure your engine is full and topped-off.”

A routine loss of coolant due to leaks and other maintenance issues can be expected. In these cases, topping off with the appropriate 50% pre-diluted coolant is ideal. If an engine has encountered cooling system failure, draining and replacing the coolant with a fresh fill of a quality coolant is recommended.

“I would not recommend that coolant collected from a leaking system or a system being drained be reused,” Woyciesjes says. “Given everything within the engine that relies on the cooling system, it is much safer to refill the system with a fresh batch of antifreeze/coolant.”

Antifreeze/coolant should:

  • Provide freezing protection to the lowest temperature encountered.
  • Provide effective inhibition of corrosion for all cooling system metals through a wide range of temperatures.
  • Provide efficient transfer of engine heat to help control critical metal temperatures.
  • Maintain minimum engine temperature for fuel and lubrication efficiencies.
  • Increase the cooling index to help prevent boilover and over-heating failures.

Unless routine testing reveals a change is needed earlier, following engine manufacturer guidelines is the best practice for ensuring appropriate antifreeze/coolant protection.

Effective antifreeze/coolant maintenance is not just a seasonal concern and it is not just about protecting an engine from running too hot or too cold. Responsible testing recognizes coolant has key protective characteristics that can minimize additional issues such as corrosion or scaling buildup.

Colin Dilley is the director of technology for Prestone Products Corp. He can be reached at Prestone manufactures and markets Prestone Command antifreeze/coolant and related products. You can find more at

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