Cooling system is the most important system that is seen under the hood of any car. If engine is the heart of a car, cooling systems can be considered as the ribs that protect the heart. This article discusses about two important components of the cooling system.
Table of Contents
Thermostat
Thermostat helps in regulating the coolant flow into the engine. Temperature of the engine is very important. If the temperature is high, it leads to Engine Knocking . Low temperatures decrease the efficiency of the engine. So, the thermostat works in such a way that the temperature is maintained so i.e. open the line if the temperatures are high and shut the valve if the temperatures are low.
Working
The thermostat is located in the engine in the coolant outlet side. When the engine does not need cooling, the thermostat is in its mean position which does not allow the coolant to flow outside the engine hence the same coolant recirculates. This is especially used to warm up the engine during starting conditions. When the engine gets hotter, the coolant gets hot as well. When the temperature of the coolant gets above 75oC, it melts the wax packed in the capsule. This pushes the valve down and the recirculation stops. The coolant goes through the above passage and reaches the radiator. The spring is provided to close the valve again at lower engine temperatures.
Pressure cap
This is also a valve placed on top of the radiator and this unlike thermostat which works on temperature changes, it works on pressure.
Working
When the pressure inside the system reaches above the critical level, the pressure of the fluid pushes the cap up and the fluid flows to the overflow tank. Whenever there is a pressure drop, vacuum is generated and coolant is taken from the tank.
Why control pressure?
Before answering this let me say why there is an increase in pressure. As the engine gets very hot at times, the coolant also gets very hot, it expands and hence pressure increases.
By controlling the pressure, we control the boiling point which is very important in a cooling system. When it is not controlled, the coolant vaporises as it comes out of the engine. This can damage the pump very badly also cooling won`t be very good.
Never touch the cap as it will be very hot.