A car engine produces a lot of heat when it is running, and must be cooled continuously to avoid engine damage. Generally this is done by circulating coolant liquid usually water mixed with an antifreeze solution through special cooling passages. Some engines are cooled by air flowing over finned cylinder casings.
Main Components of Engine Cooling System
1- Water pump
It is said to be the heart of engine cooling system. Water pump has a radial impeller inside its casing which is driven by engine itself. Serpentine belt is used to deliver rotational motion of engine main pulley to the water pump pulley.
2- Radiator
Radiator acts as a heat exchanger for an engine. it is usually made up of aluminium, and have lots of small diameter pipes with fins mounted on them. It exchanges the heat of hot water coming from engine with surrounding air. it also has an inlet port, outlet port, drain plug, and a pressure cap.
3- Thermostat
It is the thermostat which acts as a valve for coolant and allows it to flow through radiator only after exceeding a particular temperature value. Thermostat has paraffin wax in it which expands at a particular temperature and opens it up at that temperature.
4- Coolant Temperature Sensor
As name suggests it is a temperature sensing device in engine cooling system and it monitors the engine temperature. It provides the data required to control the operation of radiator fan. The engine temperature display at driver’s console gives reading according to the data provided by coolant temperature sensor. Further in the ECU controlled vehicles its data is used to optimize the fuel injection and ignition timings of engine for better performance of vehicle.
5- Rubber Hoses
In engine cooling system,these rubber hoses are required to make connection between water pump, radiator and engine so that water or coolant will flow through them thus completing the circuit.
6- Radiator overflow tank
It is a plastic tank generally mounted close to radiator and has inlet port connected with radiator and one overflow outlet. It is the same tank where you put in water before ride.
How the Engine Cooling System Works
1 – Some heat is sent through the exhaust valve, where exhaust gases move the heat away from the engine. But the exhaust valve can’t get ALL the heat out. The remaining heat is absorbed by the internal engine. So, there’s still work to do! This is where the coolant comes in to save the day.
2 – When your engine starts (even before the temperature goes way up), the water pump springs into action. It starts distributing coolant to the areas around the engine block to absorb the high temperatures.
3 – This gets the total coolant flow in motion. Coolant travels from the engine block to the cylinder head, then towards the radiator outlet.
4 – The thermostat plays a key role as the coolant comes back toward the radiator. It contains and restricts coolant flow until the coolant doesn’t go above normal operating temperature, which for most cars is around 225 degrees Celsius.
5 – Bypass hoses carry coolant to the heater core, only if the heater inside the cabin is turned on. Obviously, in the summertime, this part of the process is skipped. (Unless you’re one of those people that enjoy riding around with the heat on when it’s 98 degrees outside.)
6 – Back to the thermostat real quick. Once the coolant approaches normal operating temperature (just south of 200 degrees), the thermostat “opens up” and allows coolant into the radiator. Without this crucial step, your car’s coolant system quickly goes kaput.
7 – Next, the coolant enters the radiator and the fan automatically turns on. In order to avoid pressure buildup, the radiator’s pressure regulating valve provides an emergency outlet. If opened, coolant goes through the pressure regulating valve to the overflow reservoir.
8 – The radiator uses both gravity and cool air to decrease the coolant temperature. As the coolant moves downward in the radiator, outside air flows through the radiator, thus providing a cooling boost. Plus, the radiator fan also helps cool the temperature in the radiator.
9 – By the time the coolant goes from the radiator’s upper to lower area, the coolant has undergone enough heat loss to truly be considered “coolant.”
10 – Wash, rinse, repeat. Steps 1-9 are repeated as long as the car engine is running.
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