Importance and Working of Coolants in Heavy Duty Vehicles

Composition of a Coolant

Coolant is primarily a mixture of de-ionized water, glycol (mainly ethylene glycol or propylene glycol) and chemical additives. It is incumbent to select a coolant according to your requirement. The choice depends on the kind of environment and temperatures the engine is frequently exposed to. In a hot climate, an ideal coolant protects itself from boiling off into air due to overheat and in a cold climate, it does not freeze. At least 40% of the engine problems are due to lack of sufficient cooling.

Types of Coolants:

Depending on the usage and applications, there are at least 3 types of coolants used in heavy duty vehicle engines. They are as follows

1. Traditional Coolant
These are the regular or conventional coolants having corrosion inhibiting properties that protect the metals such as steel, aluminum and copper from corrosion. In heavy duty engines, this coolant provides excellent protection against wet sleeve liner corrosion. These coolants are typically found in green or purple color. The corrosion inhibitors in the coolant have faster depletion rate and hence a limited lifespan.

2. OAT Coolant
OAT or Organic Acid Technology are silicate free and long life coolants. Unlike the traditional coolants, the carboxylate acid corrosion inhibitors used in them have very low depletion rates. Hence, frequent periodical fueling of Supplemental Coolant Additives is not required and one refill can often be used over the engine’s lifetime. They are typically red or orange in color. It also provides an outstanding protection of aluminum at high temperatures.

3. Hybrid Coolant
This coolant technology combines the benefits offered by traditional corrosion inhibitor technology and combines this with the benefits of OAT corrosion inhibitor technology. This coolant is found typically in yellow and red color. They are used in both light and heavy duty diesel applications. This hybrid technology is also referred to as HOAT technology.

Why Coolant is Important in Heavy Duty Engines?

Coolants are used because simply water is not appropriate. The property of water makes it boil and evaporate at high temperatures and freeze at low temperatures, hence defeating the purpose of a coolant. Coolants are specifically designed to sustain extreme temperatures thereby protecting the heavy duty engines. It maintains the temperature using efficient heat transfer without which the engine would either freeze or burn out. Also, the anti-corrosion property of the coolants save the metal components of the engine from getting corroded and oxidized. Without an efficient cooling mechanism, the lifespan and efficiency of the engine will be reduced.