One very important system in our beloved automobile is the cooling system. Since the engine generates a lot of heat when it is operating, it must operate at a certain temperature for it to be efficient. If the temperature gets to high, the engine could seize. If the engine runs below the required temperature, it would not run efficiently. The job of the cooling system is to keep the engine temperature just right. Modern combustion engines are what are known as liquid cooled engines. Water is used as a medium to cool down the engine.
If you get a cross-section of the cylinder head and the engine block, you would notice chambers around the combustion chamber and the cylinders. These are known as water jackets. They allow water to circulate around the engine and absorb the heat generated in the combustion chamber. A water pump, which is driven by the crankshaft pulley, circulates the water around the engine and radiator. The radiator removes heat from the liquid coolant as it passes through the tubes with fins around it. The tubes absorb the heat, then releases it through the fins. Air then passes through the fins removing the heat. The fan can be an electric fan controlled by a thermo switch or a clutch fan driven by the crankshaft. A thermostat is used to control the flow of liquid coolant around the cooling system. If the water in the engine block is hot, it allows the coolant to flow to the radiator to cool down.
Now, as the coolant heats up, it also expands. If the coolant expands the volume of radiator will be greater and would create pressure in the system. To relieve this pressure and regulate the increase in coolant volume the radiator cap will allow some coolant to escape and overflow to the expansion tank. This will prevent the coolant from doing damage to the system. As the temperature goes down inside the radiator the coolant will contract. As this happens a vacuum will be produced. The vacuum pressure can be enough to cause an implosion. So, to prevent this, the radiator cap will use the vacuum pressure to allow the coolant from the expansion tank to return to the radiator to fill in the vacuum. Ever wonder how you experience cracks on the top portion of your radiator (it is not because it has a plastic top). This is one reason why it happens. This could be due to a faulty radiator cap or the coolant escaping to the expansion tank cannot return.
Short story here… some time ago, I was able to talk with people from a manufacturer of radiators. They supply OEM (original equipment manufacturer) radiators to the automotive industry. I asked them if they manufacture radiator caps. They said, “they tried to,” but trying to attain the high quality standard of the auto manufacturers was very, very hard.
Not for anything, I have looked at several cars with overheating problems. A good number of them where caused by a faulty radiator cap. At one instance, the syphon/return hose inside the expansion tank fell off. The coolant could not return to the radiator causing the car to overheat.
As to the question of what coolant to use… stick with the manufacturer’s recommended brand. It is going to be a can of worms if we discuss what brand to use. But, it would be prudent to replace the cap, regularly.
Even radiators have a working life span. Having it rebuilt or overhauled can keep the cost down. But from an engineering and performance standpoint, they also wear down, faster. Cooling efficiency goes down.
Another part of the cooling system is the lubricating system. People don’t really associate lubrication with cooling. But if you think about it, if you don’t have oil in your engine… your engine would seize. The oil minimizes friction between the moving parts(friction causes heat). If the oil system is in good shape you can keep friction to a minimum level. Having an oil change regularly and flushing the engine once in a while will prevent sludge from forming inside the engine.
Having an efficient cooling and lubricating system will help you through the up coming summer season. A system which will surely benefit from a good cooling system is the Air Conditioning system of our cars. This we will dwell into, next time.