The most common four-cylinder car traveling at 90 km per hour on the road will make almost 5000 controlled explosions per minute inside the cylinders as the spark plugs ignite the mixture of air and fuel in each of the cylinders. This is what propels the car along the road. These explosions generate an excessive amount of heat and destroy the motor within minutes if the heat is not controlled. The engine cooling system (ECS) is designed to control and regulate these high temperatures.
Modern refrigeration systems have not changed much compared to older refrigeration systems, but have become much more efficient and reliable in doing their job. The basic cooling system still consists of liquid coolant circulating through the combustion engine block and cylinder head (or heads in a V-configuration engine) and forced into the radiator to be cooled by counterflow air passing through the grille on the front of the car.
Radiator must maintain a constant temperature in the engine, regardless of whether the air temperature is hot +40 degrees or cold 30 degrees below zero. If the engine temperature is very low, this will result in reduced fuel consumption and increased emissions to the environment. If the engine temperature is too high, the engine will be damaged. The high temperature difference between the engine coolant and the outside air makes heat transfer more efficient. SOD consists of a coolant, channels inside the cylinder block and cylinder head, a water pump for coolant circulation (antifreeze / antifreeze or ordinary water), a thermostat for controlling the temperature of the coolant, and a radiator for cooling this liquid.
The engine coolant performs the main function of convective heat transfer for the motor. The coolant is a mixture of water, antifreeze, corrosion inhibitors and lubricants. The refrigerant was designed to overcome the shortcomings of water as a heat transfer medium. Many modern vehicles are equipped with extended life or long life coolant that is rated for up to five years or 250 km. Green coolant usually lasts two years or 000 km. The right mix and quality of coolant will prevent freezing in winter, prevent boiling in summer, prevent rust and corrosion of metal parts, be a good conductor of heat, and help prevent electrolysis.
Principle of operation
Each cooling system of a car works by circulating liquid refrigerant through passages in the cylinder block. As the coolant passes through these channels, heat is transferred from the engine components to the coolant. The heated coolant then travels through a rubber hose to a radiator at the front of the engine bay. As it passes through the thin tubes in the radiator, the hot fluid is cooled by the airflow entering the engine compartment through the grille in front of the car. After cooling, the fluid returns to the engine to absorb more heat. The water pump is designed to maintain fluid circulation in the system while the engine is running.
A thermostat is installed between the engine and the radiator to keep the coolant above a certain set temperature to keep the engine running optimally. If the coolant temperature falls below this temperature, the thermostat blocks the flow of coolant to the radiator, pushing the coolant instead through the bypass directly back into the engine. The coolant will continue to circulate in this manner until the optimum operating temperature is reached, at which point the thermostat will open and allow the coolant to return through the radiator to cool.
The cooling system is designed to pressurize to prevent the coolant from boiling over. However, too much pressure will cause hoses and other components to rupture and leak, so a system is needed to relieve the pressure if it exceeds a certain point. The work of maintaining pressure in the cooling system belongs to the radiator or tank cap to restore pressurized coolant. The cap typically increases the pressure in the cooling system by 14 or 15 psi and raises the boiling point by about 43 degrees Fahrenheit. The cap releases pressurized coolant into the coolant overflow tank. This fluid is then returned to the cooling system after the engine has cooled down. Never remove the radiator cap immediately after stopping the engine, as the pressurized coolant will immediately boil as soon as the pressure is released. Burns and serious injury will almost certainly occur.
There are several rubber hoses that connect parts of the cooling system. The two main hoses are called the upper and lower radiator hoses. These two hoses direct the coolant between the engine and the radiator. The heater hoses carry heated coolant from the engine to the heater core. One of these hoses may have a built-in heater control valve to block heated coolant from entering the heater core when the A/C is set to maximum cooling. Another hose, called the bypass hose, is used to circulate coolant through the engine, bypassing the radiator when the thermostat is closed. Some engines do not use a rubber bypass hose. Instead, they may use a metal tube or have a built-in passage in the front engine casing.
On the back of the heatsink on the side closest to the engine, one or two electric cooling fans are installed inside the case, which is designed to protect fingers and direct airflow. The fans are controlled by the car's computer. The sensor monitors the temperature of the engine and sends the information to the computer. The computer determines if the fan should be on and activates the fan relay if additional airflow through the heatsink is required. The fans keep air flowing through the radiator when the vehicle is moving slowly or stopped while the engine is running. If the fans stop working, the engine temperature will start to rise every time the car is stopped.
If the car is equipped with air conditioning, an additional radiator, called the air conditioner condenser, is installed in front of the radiator of the engine cooling system. The air conditioning condenser also needs to be cooled by the airflow entering the engine compartment. If the air conditioner is turned on, the system will keep one electric cooling fan running even if the engine is not running. If no air flows through the air conditioner condenser, the air conditioner will not be able to cool the air entering the vehicle interior.
Conclusion
An overheated engine will quickly fail. Proper maintenance of the cooling system is vital to the life of the motor and the smooth functioning of the cooling system. It is important that a certified technician inspect all components of the cooling system annually. On inspection, the technician should check the pressure on the radiator cap to make sure the cooling system is operating at the proper pressure level, run the vehicle up to operating temperature to make sure the engine thermostat is properly controlling the engine temperature, inspect the coolant fluid level, and visually inspect for any signs coolant leaks, check the coolant protection level and pH level to determine if the coolant should be replaced, and visually inspect the coolant hoses.