How do engine coolants work?
In: 1
Engines do produce a lot of heat. First as the compress the air which makes it hot, and then when the fuel is burned the temperature increases even further. If the engine gets too hot it will fail. The metal will warp or even melt. The lubricating oil will decompose or burn turning it into charcoal. Metal will expand so pieces will no longer fit together. Rubber hoses and such will melt. Even things like spark plugs may end up melting so they stop working.
So the engine can not get too hot and it needs to be cooled. Some smaller engines can be air cooled. Just letting enough air flow over it and fill the outside with cooling ribs for more surface area will cool them down enough. But this is not enough for larger engines like most of the ones you find in cars, and even medium sized bikes. Air is not good at transporting heat so we need much larger surface area. This is what the radiator is for. Tiny fins in the radiator makes for lots of surface area to carry the heat away. But to get the heat from the engine to the radiator we use a liquid. So the engine block have lots of coolant passages going through it and a coolant pump to pump the liquid from the engine block to the radiator and back. Some vehicles might have other things connected to the cooling loop. The liquid is basically water, but it is best practice to add things like glycol to it in order to prevent it from freezing if you park in winter and various other things to prevent it from rusting out the metal.
There are lots of little details to this system. The radiator cap is designed to let steam vent if the radiator can not keep up and the coolant boils. There is often an expansion tank so the coolant can expand when it is hot and shrink as it gets cold, although this tank is usually integrated in the radiator. The engine have freeze plugs to let the water out if it would freeze in winter. There is a thermostat to allow coolant to bypass the radiator if it is cold in order to heat up the engine to operating temperature faster and keep it at this optimal temperature. Some of the coolant is sent to the cabin heater to heat up the cabin if it gets cold. Certain cars have electrical heaters in them to allow for easier cold start, or they may have connectors to combine the cooling loops of a running car to a parked car to heat it up before starting it. There are lots of these details and concepts around the cooling system of a car.
Engines do produce a lot of heat. First as the compress the air which makes it hot, and then when the fuel is burned the temperature increases even further. If the engine gets too hot it will fail. The metal will warp or even melt. The lubricating oil will decompose or burn turning it into charcoal. Metal will expand so pieces will no longer fit together. Rubber hoses and such will melt. Even things like spark plugs may end up melting so they stop working.
So the engine can not get too hot and it needs to be cooled. Some smaller engines can be air cooled. Just letting enough air flow over it and fill the outside with cooling ribs for more surface area will cool them down enough. But this is not enough for larger engines like most of the ones you find in cars, and even medium sized bikes. Air is not good at transporting heat so we need much larger surface area. This is what the radiator is for. Tiny fins in the radiator makes for lots of surface area to carry the heat away. But to get the heat from the engine to the radiator we use a liquid. So the engine block have lots of coolant passages going through it and a coolant pump to pump the liquid from the engine block to the radiator and back. Some vehicles might have other things connected to the cooling loop. The liquid is basically water, but it is best practice to add things like glycol to it in order to prevent it from freezing if you park in winter and various other things to prevent it from rusting out the metal.
There are lots of little details to this system. The radiator cap is designed to let steam vent if the radiator can not keep up and the coolant boils. There is often an expansion tank so the coolant can expand when it is hot and shrink as it gets cold, although this tank is usually integrated in the radiator. The engine have freeze plugs to let the water out if it would freeze in winter. There is a thermostat to allow coolant to bypass the radiator if it is cold in order to heat up the engine to operating temperature faster and keep it at this optimal temperature. Some of the coolant is sent to the cabin heater to heat up the cabin if it gets cold. Certain cars have electrical heaters in them to allow for easier cold start, or they may have connectors to combine the cooling loops of a running car to a parked car to heat it up before starting it. There are lots of these details and concepts around the cooling system of a car.
Liquid cooled engines have channels that go through them that allow liquid to travel via something called a water pump. As the liquid goes through the channels, it picks up heat generated from the engine and then it is deposited at the top of the radiator. The liquid then drains to the bottom while the fins in the radiator spread the heat to a large area and is blown on by the radiator fan and air coming in from driving. The cooler liquid is then shot through the engine again with the water pump and the whole process starts again.
A common problem with engines is sludgy oil / coolant, there is a failure somewhere (all the moving parts in an engine sit in what is essentially a bath of oil except for the combustion chambers) which is allowing the coolant that moves through the engine to mix with the oil.
Not all engines are liquid cooled, Lycoming and Continental produce 4 and 6 cylinder horizontally opposed engines that are entirely air cooled. They can do that because there is a huge prop that acts as a fan *and* as the airplane goes up in altitude the air cools significantly, making liquid cooling mostly unnecessary.
Liquid cooled engines have channels that go through them that allow liquid to travel via something called a water pump. As the liquid goes through the channels, it picks up heat generated from the engine and then it is deposited at the top of the radiator. The liquid then drains to the bottom while the fins in the radiator spread the heat to a large area and is blown on by the radiator fan and air coming in from driving. The cooler liquid is then shot through the engine again with the water pump and the whole process starts again.
A common problem with engines is sludgy oil / coolant, there is a failure somewhere (all the moving parts in an engine sit in what is essentially a bath of oil except for the combustion chambers) which is allowing the coolant that moves through the engine to mix with the oil.
Not all engines are liquid cooled, Lycoming and Continental produce 4 and 6 cylinder horizontally opposed engines that are entirely air cooled. They can do that because there is a huge prop that acts as a fan *and* as the airplane goes up in altitude the air cools significantly, making liquid cooling mostly unnecessary.
Liquid cooled engines have channels that go through them that allow liquid to travel via something called a water pump. As the liquid goes through the channels, it picks up heat generated from the engine and then it is deposited at the top of the radiator. The liquid then drains to the bottom while the fins in the radiator spread the heat to a large area and is blown on by the radiator fan and air coming in from driving. The cooler liquid is then shot through the engine again with the water pump and the whole process starts again.
A common problem with engines is sludgy oil / coolant, there is a failure somewhere (all the moving parts in an engine sit in what is essentially a bath of oil except for the combustion chambers) which is allowing the coolant that moves through the engine to mix with the oil.
Not all engines are liquid cooled, Lycoming and Continental produce 4 and 6 cylinder horizontally opposed engines that are entirely air cooled. They can do that because there is a huge prop that acts as a fan *and* as the airplane goes up in altitude the air cools significantly, making liquid cooling mostly unnecessary.
Basically water that you send through the engine to cool it, then you take the hot water to a heat exchanger that cools the water using outside air.
The coolant can’t be simple water cause water is full of salt and at high temperature it becomes corrosive to metals. Coolant you buy is likely made with purified water and additives.
Additives can be chemicals that make water less corrosive.
then some other additive is present to prevent the water to freeze (more of it or less of it according to the temperatures of the place/country, the recommended temperature is written on the coolant container and should match the specs of your car manual, adjusted for local temperatures)
Then there are additives that may raise the boiling point so the coolant will not boil in the engine. Boiling creates vapors that create pressure and this pressure can blow a hole in a pipe or make other mechanical damage.
Then there are additives that keep the circuit clean. Imagine a sort of soap that prevents debris to build up in the pipes.
Distilled water is a decent substitute for coolant if you need it. But at that point, you are in a shop so just buy the coolant is a better option.
Tap water is usable in an emergency, not recomended long term. At the end of the emergency is better to drain the system and refill with proper coolant for all the above reasons.
For all this reasons, some engines are oil cooled or air cooled, it’s more common on machinery and aviation, and in both cases it’s a trade off, losing some performance in order to achieve higher reliability. Again water cooling is the cheapest way to cool powerful engines, not the most reliable.
Basically water that you send through the engine to cool it, then you take the hot water to a heat exchanger that cools the water using outside air.
The coolant can’t be simple water cause water is full of salt and at high temperature it becomes corrosive to metals. Coolant you buy is likely made with purified water and additives.
Additives can be chemicals that make water less corrosive.
then some other additive is present to prevent the water to freeze (more of it or less of it according to the temperatures of the place/country, the recommended temperature is written on the coolant container and should match the specs of your car manual, adjusted for local temperatures)
Then there are additives that may raise the boiling point so the coolant will not boil in the engine. Boiling creates vapors that create pressure and this pressure can blow a hole in a pipe or make other mechanical damage.
Then there are additives that keep the circuit clean. Imagine a sort of soap that prevents debris to build up in the pipes.
Distilled water is a decent substitute for coolant if you need it. But at that point, you are in a shop so just buy the coolant is a better option.
Tap water is usable in an emergency, not recomended long term. At the end of the emergency is better to drain the system and refill with proper coolant for all the above reasons.
For all this reasons, some engines are oil cooled or air cooled, it’s more common on machinery and aviation, and in both cases it’s a trade off, losing some performance in order to achieve higher reliability. Again water cooling is the cheapest way to cool powerful engines, not the most reliable.
Basically water that you send through the engine to cool it, then you take the hot water to a heat exchanger that cools the water using outside air.
The coolant can’t be simple water cause water is full of salt and at high temperature it becomes corrosive to metals. Coolant you buy is likely made with purified water and additives.
Additives can be chemicals that make water less corrosive.
then some other additive is present to prevent the water to freeze (more of it or less of it according to the temperatures of the place/country, the recommended temperature is written on the coolant container and should match the specs of your car manual, adjusted for local temperatures)
Then there are additives that may raise the boiling point so the coolant will not boil in the engine. Boiling creates vapors that create pressure and this pressure can blow a hole in a pipe or make other mechanical damage.
Then there are additives that keep the circuit clean. Imagine a sort of soap that prevents debris to build up in the pipes.
Distilled water is a decent substitute for coolant if you need it. But at that point, you are in a shop so just buy the coolant is a better option.
Tap water is usable in an emergency, not recomended long term. At the end of the emergency is better to drain the system and refill with proper coolant for all the above reasons.
For all this reasons, some engines are oil cooled or air cooled, it’s more common on machinery and aviation, and in both cases it’s a trade off, losing some performance in order to achieve higher reliability. Again water cooling is the cheapest way to cool powerful engines, not the most reliable.
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