Importance of Coolants Today

By: Jonathan Sowers, CLS

Yes, we all agree that Extended Life Coolant (ELC) is one of the most significant technological advancements in antifreeze development since the introduction of ethylene glycol in the 1930’s.  It is similar, in a way, to how we view synthetic motor oils.  It will last an extraordinarily long time, with very slow additive depletion, and will provide excellent protection.  However, just as in the case of engine oils, the coolant in your radiator, whether ELC or Conventional, can be exposed to contamination, coolant dilution, additive mixing, and oxidation due to extreme temperatures. 

Modern diesel engine design is driven by demands for increased power, increased reliability, better fuel economy and let’s not forget reduced emissions.  To meet these demands OEMs have added beefed-up turbochargers, charge air coolers, EGR and other emission reducing equipment, electronically timed fuel injection and computerized combustion controls – all placing higher thermal demands on the cooling system.  Changes in cooling system technology have not kept pace with the recent frequent engineering advances in the engine.  There we see increased flow rates, higher pressures (radiator cap) to control the boiling point, better performing fans and fan shrouds, sometimes increased radiator size, but not everywhere. There is also a trend away from copper toward lighter aluminum coolers and heat exchangers, which means we have to take a closer look at our coolant chemistry and inhibitor additive package.

Oh, yes, let’s not forget about the other engine components that contribute heat to the cooling system. Things like heater blocks, the HVAC system, transmissions, oil coolers, etc., all adding additional stress to the cooling system and coolant in particular.

Heavy duty diesel engines today typically run at temperatures of 250ºF and higher. 

The impact of all this on the coolant and coolant formulations is significant.  Ethylene glycol is hydrocarbon based, and as such will oxidize when exposed to high temperatures – just like the lubricating oil in the engine.  It “breaks down” and forms acidic byproducts.  Additives, such as nitrites (used to inhibit corrosion of cast iron and liner pitting due to cavitation), will oxidize and be reduced to nitrates and lose their effectiveness.  The higher temperatures also enhance the formation of scale, from use of improper water in the original charge or as make-up.

This all sounds pretty scary, but there are things you can do to help yourself.  For one thing, there are a variety of coolants available for use, usually classified by their additive chemistry.  Familiarize yourself with their performance characteristics and see which will meet your needs and budget.  Make sure you are maintaining your coolant system with correct water (distilled) and you are not mixing coolant chemistries (such as adding Conventional as make-up to ELC).  It is a good idea to consider making it a practice to use pre-mixed solutions provided by the vendor.  You will need to be sure to regularly inspect and test the coolant system according to OEM suggested PMs. 

For more information on coolant testing services offered by Staveley please click here.