Every passenger vehicle produced today with an internal combustion engine in it has a cooling system for the engine itself. All common four stroke engines are liquid cooled and the cooling system is made up of many different components.
The most common components in a cooling system are: water pump radiator, thermostat, heater matrix/heater core, cooling fans, Coolant temp sensors, radiator cap and overflow bottle.
Starting with the water pump, it does as its name implies, pumps the water (coolant) through the system to aid in cooling. It works by centrifugal force, drawing coolant in through the inlet side and expelling it through the outlet in order to circulate it throughout the system.
The radiator is the systems holding tank which is specially designed to have fluid pushed in the inlet side of it, then as the fluid pushes through the radiator it is forced along the vanes, which are exposed to cool air by the air that passes over the radiator when driving, this then cools the coolant as it enters the outlet side of the radiator to go back into the system.
The thermostat is located in the engine block in the direct coolant flow; the thermostats job is to regulate the flow of coolant through the system based on the temperature of the coolant itself. When the coolant is cold, the thermostat stays closed so it limits the amount of flow allowing the engine to heat the coolant that is inside of it to the proper operating temperature. Once this temperature is reached the thermostat opens allowing cool fluid into the block to repeat the process again.
The heater matrix allows the interior passenger compartment to use heat from the engine to warm the cabin. Warm coolant flows through the matrix and a fan mounted on the backside of it pushes the heat into the cabin.
The cooling fans serve an important purpose. If you are in heavy traffic or standing idle, no air is going over the radiator fins to cool the coolant. The fans make this so it is not a problem; they are governed by the coolant temperature switch. The switch activates once the engine temperature hits a certain set value, then sends current to the fans in order to force air over the radiator fins eliminating the need for the vehicle to be moving to cool itself.
Two parts are left to normal cooling systems, the radiator cap and the overflow bottle. These work in conjunction to each other. The radiator cap is meant to hold in pressure to a set rating, normally between 10 and 16 lbp of pressure. Since pressurised fluid has a higher boiling point it allows the water/coolant mixture to surpass the boiling point before actually boiling. If the pressure in the system exceeds the cap rating, the cap is designed so that the spring depresses allowing the coolant to be expelled from the system into the overflow tank. When the system is working properly the overflow tank is designed to be able to re draw the coolant back into the system once the vehicle cools down in order to keep the coolant level to the proper level.
