Heat peaks require targeted cooling
In modern Volvo heavy-duty engines, the highest thermal loads are mainly located in the cylinder head. Critical areas include:
- Exhaust valves and valve seats
- The area between two cylinders
- The vicinity of injectors or spark plugs
When heat in these areas is not sufficiently dissipated, the local metal temperature rises rapidly. Because engine components do not heat up and cool down uniformly, additional thermal stresses occur in the material. This increases the risk of deformation, cracking, and accelerated wear.
Customized for local loads
To mitigate these risks, Volvo prescribes a coolant for engines such as the D11K1 and D13K diesel engines and the G13 gas engine that meets the VCS-2 specification, applied in a fixed mixing ratio of 40% antifreeze and 60% water.
This ratio is chosen to effectively dissipate heat under heavy operating conditions. Water efficiently absorbs heat, while the VCS-2 additives provide:
- Metal protection
- Seal protection
- Stability at elevated operating temperatures
Thus, the coolant directly contributes to stable heat dissipation, even under prolonged stress.
From specification to practice
For workshops and fleet managers, this cooling strategy means that not only the correct specification is important, but also a coolant that reliably adheres to these requirements in practice. Deviations in composition or mixing ratio can restrict heat dissipation and lead to higher local temperatures.
The use of a coolant that does not meet the VCS-2 specification can have consequences for the warranty and may result in increased wear or serious engine damage. In practice, this requires a coolant that demonstrably meets this OEM specification, such as Eurol Coolant -26°C VCS-2.
Differences between diesel and gas engines
The thermal load differs between diesel and gas engines.
In diesel engines, high combustion pressures and prolonged operation at high torque create peak loads in the cylinder head. Components such as the EGR cooler and oil cooler play a crucial role in total heat dissipation.
In the G13 gas engine, combustion temperatures are higher and more constant. As a result, the heat load is prolonged, emphasizing the thermal stability of the coolant at higher operating temperatures.
Post-operation heat
After heavy use, heat remains in the engine even as the workload decreases. This so-called heat soak effect is a normal part of the thermal profile of modern engines.
At this stage, the freezing point is not crucial, but rather the coolant's ability to absorb and retain heat. Water plays a significant role in this, while additives protect engine components from corrosion and deposits at elevated temperatures.
Implications for maintenance
Volvo's heavy-duty engine cooling strategy demonstrates that cooling is an essential part of engine protection. By using a coolant that meets the correct specification and mixing ratio, workshops can contribute to:
- Stable engine operation
- Control of local heat loads
- Extended service life of engine components
The right coolant according to the VCS-2 specification thus forms a practical basis for reliable daily maintenance.
