Cooling System Efficiency
The cooling system is a vital element to the reliable running of the engine. Regulating the engine temperature maximises engine performance, efficiency and economy.
With ever-increasing fuel efficiency and greater power demanded from modern engines, the pressures on the cooling system components are also increased in order to maintain the engine’s performance. Key system components include: the radiator, intercooler, cooling fan, thermostat, water pump and hoses.
Located at the front of the vehicle, either in front of, or behind the fan assembly, the radiator uses coolant to remove heat generated by the engine, and expels it into the atmosphere. Adequate cooling capacity for the car ensures optimum engine performance. In addition it provides coolant to the oil and EGR coolers. Maintaining the quality of the coolant will ensure water tightness under thermal loop pressure. The integrity of the radiator acts to resist the vibrations, torsions and bear the pressure pulsation caused by each engine start. A quality radiator is able to resist long term external corrosion caused by environmental conditions, such as salt spray in winter.
The radiator cap is the safety valve of the cooling system. It is designed to add pressure to the cooling system and increases the boiling point of the coolant. The cap also seals the system, keeping the air out and preventing corrosion.
The fan system forces air through the radiator. This helps to prevent the coolant from overheating. At high speeds there is naturally enough air flowing into the system to help keep things cool. At low speeds, driving in stop/start urban conditions for example, an electric motor drives the fan.
The intercooler is used in conjunction with the turbocharger. It is positioned between it and the inlet manifold. The turbo compresses more air into the engine, allowing more fuel to burn, thereby increasing power. Without an intercooler the compressed air temperature increases to as much as 180°C, and air pressure increases (>2.5 bar) causing mechanical stress within the engine. The intercooler, a heat exchanger, lowers air temperature to 50°C on its exit from the turbocharger, reducing mechanical stress. Cooled air is denser allowing an improved quantity of air to enter the combustion chamber.
This constantly monitors the temperature of the system and regulates coolant flow through the radiator. A good thermostat reduces engine warm-up time and regulates the engine’s operating temperature to ensure maximum performance.
To improve the efficiency of the cooling system, vehicle manufacturers have developed electronic thermostats that are far more sensitive to variations in temperature than the traditional thermostat, and which constantly alter the flow of coolant around the engine to maintain optimum temperature.
In addition to the changes to the thermostat, temperature sensors are now located around the engine to feedback operating temperature information to the ECU, to ensure that there are no ‘hotspots’ in the system.
A water pump circulates coolant through the cooling system by pushing fluid through the engine and into the radiator. As the coolant passes through the radiator it cools down before returning to the engine. This helps to prevent the engine from overheating.
A water pump is usually driven by the engine through the drive belt. Looking to the future, vehicle manufacturers are developing electronic water pumps, which along with the thermostat and temperature sensors allow the ECU to finely control the engine temperature according to engine load. Driver benefits include improved fuel economy and reduced engine emissions.
In addition to radiators, thermostats and water pumps, modern engines distribute coolant via hoses to components such as carburetor housings, fuel injection throttle bodies, turbochargers and oil coolers. Hoses must be durable in order to cope with the hostile environments created by increasingly compact engine compartments.
The hose range from Gates is not only extensive, but also versatile: curved hoses were developed to replace factory mouldings; silicone hoses in straight, curved or 90-degree variants have been developed for a wide range of higher temperature applications, and the Extra Service range provides solutions for trucks and buses.
Cooling system faults are among the major causes of roadside breakdowns in all seasons. Early detection of component deterioration is essential to avoid bigger problems in the future. For example, age affects hose performance and a reaction between the antifreeze chemicals in coolant and some radiator fittings can attack hose tubing and cause premature hose failure – even in low mileage applications.
Gates’ Ethylene Propylene Diene Monomer (EPDM) hoses provide a solution to the breakdown of hose exteriors by ozone pollution, while Electro Chemically Resistant (ECR) hoses provide the best preventative measure against electrochemical damage.
As part of an ongoing campaign, Gates is urging garage owners to promote further cooling system preventative maintenance options to motorists while memories of inconvenient breakdowns are still fresh in their minds.
Faults in radiators and intercoolers can be detected due to loss of power, noticeable when accelerating, or obvious crash damage. Higher emissions (which could lead to MOT failure) can now be detected by fault code readers in modern cars.
Reasons for radiator and intercooler failure
Radiators and intercoolers should always be replaced after a front end crash. This avoids the potential hazards of increased overheating, increased fuel consumption and at worst, head gasket failure.
When any part of the cooling system is replaced it is essential that the system is flushed out and new coolant added. This will help to ensure the continued efficiency of the whole system.
When working on the cooling system, always choose OE quality Aftermarket parts. Fitting substandard parts can have dire consequences. An OE quality part is designed and manufactured to perform day-in day-out, in all conditions and environments, but a non- OE quality product could result in damage to the engine.