- What is the primary function of an engine coolant?
- What other functions does a Coolant offer?
- What are the principle components of a Coolant?
- What is the role of glycol in the coolant?
- Why do we use high quality de-ionized water as a coolant ingredient?
- Can a glycol based coolant concentrate be used as is?
- What is the operating temperature range of various water and coolant concentrate blends?
- What simple tests can be used to check in-service coolant?
- Can a conventional coolant based on silicate inorganic corrosion inhibitors be used to top-up an extended life coolant based on organic corrosion inhibitors?
- What is the difference between a SCA and a Coolant Extender?
- What is cavitation and what impact does it have?
What is the primary function of an engine coolant?
To effectively remove heat generated from the combustion of fuel in the engine block.
What other functions does a Coolant offer?
Coolant provides corrosion protection to engine components, freeze protection when subject to sub zero temperature, boil protection, heat transfer to the passenger compartment of vehicles, lubrication to the water pump and general chemical and oxidative stability to ensure efficient functioning of the cooling system.
What are the principle components of a Coolant?
Coolant is comprised of a heat transfer medium, typically high quality water and glycol, various corrosion inhibitors and functional additives depending on the coolant type.
What is the role of glycol in the coolant?
Water is an effective heat transfer fluid but has a limited operating temperature range. Glycol when combined with water offers a wider operating temperature range than either fluid used by itself. Ethylene glycol is the most prevalent glycol used in coolant based on functionality, cost and availability. Depending on the application and climate, an engine coolant may be based on water only if an extended operating temperature range is not required.
Why do we use high quality de-ionized water as a coolant ingredient?
Water that is free of dissolved minerals is required for use in coolant since minerals contribute to scale formation, which impedes efficient functioning of the coolant system, leading to a failure. All global coolant specifications and standards have quality requirements for the water appropriate for use in a coolant product. Municipal or well water can contain appreciable amounts of dissolved minerals and fine particulate and is not recommended to dilute coolant concentrate for this reason. De-ionized water has been specifically processed to remove dissolved minerals and particulate making it ideally suited for use in coolants.
Can a glycol based coolant concentrate be used as is?
No. Glycol based coolant concentrate in of itself does not offer sufficient heat transfer and corrosion protection characteristics. To optimize the heat transfer and other functional attributes a coolant concentrate must always be diluted with high quality water, preferable deionised water at a 50:50 ratio with coolant concentrate. Glycol based coolant concentrate should always be diluted to between 30% and 70% strength as exceeding these limits would compromise coolant performance.
What is the operating temperature range of various water and coolant concentrate blends?
Volume dilutions and resultant temperature operating ranges are provided below for typical ethylene glycol coolant concentrate.
|% ANTIFREEZE||% WATER||PROTECTION AGAINST FREEZING||*PROTECTION AGAINST BOIL-OVER|
What simple tests can be used to check in-service coolant?
A refractometer is the best tool to measure the glycol content and subsequent freeze and boil protection being offered by the coolant. Bulb type hydrometers may be less accurate and not recommended. Test strips can be used to determine select corrosion inhibitor levels as part of a proper coolant maintenance program. Most test strips on the market are specific to heavy duty diesel coolant analysis and measure either nitrite or molybdate levels.
Can a conventional coolant based on silicate inorganic corrosion inhibitors be used to top-up an extended life coolant based on organic corrosion inhibitors?
Using a conventional coolant in this manner will not disrupt the ability of the extended life coolant to protect the coolant system but will diminish its extended service life characteristics. Therefore it is not recommended to top-up an extended life coolant based on organic corrosion inhibitors with any coolant other than an extended life coolant as this will negate the extended service life offered by the original coolant in the cooling system.
What is the difference between a SCA and a Coolant Extender?
A Supplemental Coolant Additive (SCA) is used to convert an automotive rated traditional coolant into a “fully formulated” coolant suitable for heavy duty diesel use. The SCA includes those corrosion inhibitor additives necessary for protection of diesel engines. It is added as a “precharge” with the initial fill of coolant into the diesel application and typically contains a variety of inorganic corrosion inhibitors.
A Coolant Extender is used between drain intervals to maximize coolant life by replenishing corrosion inhibitor additives that have depleted from a heavy duty extended life coolant. It is used at the midpoint of the service interval of the coolant and typically contains nitrite corrosion inhibitor and other additives.
What is cavitation and what impact does it have?
Cavitation results when mechanical agitation (vibration) causes local pressure changes in a fluid. Instances of low pressure result in the immediate vaporization of the fluid and gas bubble formation and subsequently collapse when the pressure normalizes. In an engine this typically occurs within the water pump due to the mechanical action of the impeller and along the cylinder liners as a result of the piston movement (piston slap vibration) and most pronounced in diesel engines. This constant bubble creation and collapse along surfaces can be repetitive and violent enough to corrode the underlining metal resulting in cooling system failure and is of a concern with higher water to glycol ratio coolants. Select corrosion inhibitors such as nitrite and/ or molybdate are preferably used in coolant to combat this cavitation corrosion since they form barrier films on metal surfaces preventing corrosion resulting from localized bubble implosion.