The engine in the typical car runs at very high temperatures due to a variety of factors, including friction as the pistons reciprocate inside the cylinder walls and high-temperature explosions as fuel and air ignite in the cylinders to drive those pistons. Most modern cars are equipped with a liquid cooling system and its primary responsibility is to keep the engine from getting too hot. Interestingly enough, the coolant system also has to make sure the engine doesn’t get too cold. Cylinder temperatures need to remain warm in order to ensure the most efficient combustion possible of the air/fuel mixture and engine oil temperatures must be maintained at a specified minimum in order to provide the best lubricity and protection for the moving parts it coats. The cooling system contains several components that must work together in order to maintain a constant and effective operating temperature.
The heart of the cooling system is the water pump. The water pump pushes coolant through all of the hoses, pipes, tubes and reservoirs contained in this incredible circulatory system. In order to better understand how the system works, we will follow the flow of the coolant. The water pump sends fluid into the engine block where it flows through engine passages and around the cylinder walls as it makes its way to the cylinder heads. The cylinder walls and cylinder heads get very hot, as we mentioned before, due to the friction of the pistons and the heat of the explosions that drive the pistons.
A thermostat is located where the coolant leaves the engine. The thermostat is temperature sensitive and acts as a valve to that can route the coolant directly back to the water pump or through the radiator. If the fluid is cool enough, the thermostat remains closed and the coolant is directed back to the pump for recirculation into the engine. If the coolant is too hot, the thermostat opens and sends the fluid to the radiator to be cooled.
The radiator is what most people envision when they think about the engine cooling system in a car. The radiator is a series of tubes connected to a number of cooling fins. As the coolant flows through the radiator, a cooling fan blows through the radiator and conducts the heat in the coolant through the fins and into the air around the radiator. The fluid is significantly cooler once it passes through the radiator and is routed to the water pump to start the process over. In addition to managing engine temperature, the cooling system has separate circuits to cool the transmission and warm the air that heats the cabin of the car.
The engine coolant system is a vital component in the overall operation of a vehicle and needs to be inspected and maintained. Coolant hoses need to be fastened securely and replaced if any are cracked or excessively worn. Antifreeze must be topped off and its temperature properties checked to ensure they are appropriate for the weather (especially important during winter months). Understanding a vehicle’s key systems and keeping them maintained will provide owners with greater driving security and decrease the likelihood of unexpected failures and expensive repairs.