Automobile Cooling SYstem


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Automobile Cooling System Explained :

Automobile Cooling System Explained An automobile's cooling system is the collection of parts and substances (coolants) that work together to maintain the engine's temperature at optimal levels. Comprising many different components such as water pump, coolant, a thermostat , etc, the system enables smooth and efficient functioning of the engine at the same time protecting it from damage.

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The cooling system essentially comprises passages inside the engine block and heads, a  pump to circulate the coolant, a thermostat to control the flow of the coolant, a radiator to cool the coolant and a radiator cap controls the pressure within the system. In order to achieve the cooling action, the system circulates the liquid coolant through passages in the engine block and heads. As it runs through, the coolant absorbs heat before returning to the radiator, to be cooled itself. Next, the cooled down coolant is recirculated and the cycle continues to maintain the engine's temperature at the right levels.

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Engine Cooling System Components A number of different constituents enable smooth operation of the automobile's cooling system. Some of the most essential ones are explained below.

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Engine Cooling Fluids An engine coolant is a fluid which flows through the engine and prevents it from overheating by transferring the heat generated by the engine to other components that either make use of it or dissipate it. Features of an ideal coolant entail a low viscosity, high thermal capacity, has chemical inertness and is low-cost. Further, it should neither cause or promote corrosion of the cooling system.

Water Cooling Systems:

Water Cooling Systems A water cooling system accomplishes the cooling action with the help of water. There are  various components that make up the cooling system are the Air Blower, Cooling Fans, Radiator Pressure Caps, Water Pipes, Coolant Hoses, Radiator Parts, Radiators and Water Pumps. Each of these components plays an essential role. For instance, the radiator cools the coolant so that it can be reused, the water pump pumps the coolant through the system via water pipes, the Air Blower draws air through the radiator to achieve the cooling action, etc.


Valves The cooling system valves have an essential role to play. An engine's cooling system for an internal combustion engine utilizing liquid coolant, includes a liquid coolant filled radiator and engine "water" jacket, a radiator cap to pressurize the radiator, a coolant pump and a thermostat. While the thermostat determines when it is appropriate to either prohibit coolant flow or to allow coolant flow between the engine or radiator, the valve assembly act like a door that opens up and closes as required.

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Cooling System Gaskets The cooling system for engines include a cylinder block defining a water jacket with in it, which has an inlet. Further, a water pump housing is attached to the the cylinder block, and a water pump suction cover is fixed to the housing and sealed upon it by a gasket. The gasket plays an important role of projecting the water into the water jacket inlet so as to guide water within the system

Engine Cooling Systems :

Engine Cooling Systems It stands to reason that if you fill a metal engine with fuel and air hundreds of times a second and make it explode, the whole thing is going to get pretty hot. To stop it all from melting into a fused lump of steel and aluminium, all engines have some method of keeping them cool.

Air cooling :

Air cooling You don't see this much on car engines at all now. The most famous cars it was used on were rear- engined boxers like the original VW Beetle, Karmann Ghia , and Porsche Roadsters. It is still used a lot on motorbike engines because it's a very simple method of cooling. For air cooling to work, you need two things - fins (lots of them) and good airflow. An air-cooled engine is normally easy to spot because of the fins built into the outside of the cylinders. The idea is simple - the fins act as heat sinks, getting hot with the engine but transferring the heat to the air as the air passes through and between them. Air-cooled engines don't work particularly well in long, hot traffic jams though, because obviously there's very little air passing over the fins.

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.. Air cooled engines can't regulate the overall temperature of the cylinder heads and engine, so the temperature tends to swing up and down depending on engine load, air temperature and forward speed. The image on the right is ©Ducati and shows the engine from the Monster 695 motorbike. It's a good example of modern air-cooled design and you can see the fins on the engine are all angled towards the direction of travel so the air can flow through them freely.

Oil cooling :

Oil cooling To some extent, all engines have oil-cooling. It's one of the functions of the engine oil - to transfer heat away from the moving parts and back to the sump where fins on the outside of the sump can help transfer that heat out into the air. But for some engines, the oil system itself is designed to be a more efficient cooling system. BMW 'R' motorbikes are known for this (their nickname is ' oilheads '). As the oil moves around the engine, at some points it's directed through cooling passageways close to the cylinder bores to pick up heat. From there it goes to an oil radiator placed out in the airflow to disperse the heat into the air before returning into the core of the engine. Actually, in the case of the 'R' motorbikes, they're air- and oil-cooled as they have the air-cooling fins on the cylinders too.

Water cooling :

Water cooling This is by far and away the most common method of cooling an engine down. With water cooling, a coolant mixture is pumped around pipes and passageways inside the engine separate to the oil, before passing out to a radiator. The radiator itself is made of metal, and it forces the coolant to flow through long passageways each of which have lots of metal fins attached to the outside giving a huge surface area. The coolant transfers its heat into the metal of the radiator, which in turn transfers the heat into the surround air through the fins - essentially just like the air-cooled engine fins. The coolant itself is normally a mixture of distilled water and an antifreeze component.

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The water needs to be distilled because if you just use tap water, all the minerals in it will deposit on the inside of the cooling system and mess it up. The antifreeze is in the mix, obviously to stop the liquid from freezing in cold weather. If it froze up, you'd have no cooling at all and the engine would overheat and weld itself together in a matter of minutes. The antifreeze mix normally also has other chemicals in it for corrosion resistance too and when mixed correctly it raises the boiling point of water, so even in the warmer months of the year, a cooling system always needs a water / antifreeze mix in it.

The complexities of water cooling:

The complexities of water cooling . Water cooling is the most common method of cooling and engine down, but it's also the most complicated. For example you don't want the coolant flowing through the radiator as soon as you start the engine. If it did, the engine would take a long time to come up to operating temperature which causes issues with the emissions systems, the drivability of the engine and the comfort of the passengers. In truly cold weather, most water cooling systems are so efficient that if the coolant flowed through the radiator at startup, the engine would literally never get warm. So this is where the thermostat comes in to play. The thermostat is a small device that normally sits in the system in-line to the radiator. It is a spring-loaded valve actuated by a bimetallic spring. In layman's terms, the hotter it gets, the wider open the valve is. When you start the engine, the thermostat is cold and so it's closed. This redirects the flow of coolant back into the engine and bypasses the radiator completely but because the cabin heater radiator is on a separate circuit, the coolant is allowed to flow through it. It has a much smaller surface area and its cooling effect is nowhere near as great. This allows the engine to build up heat quite quickly.

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The radiator fan . In the good old days, car radiators had belt-driven fans that spun behind the radiator as fast as the engine was spinning. The fan is there to draw the warm air away from the back of the radiator to help it to work efficiently. The only problem with the old way of doing it was that the fan ran all the time the engine was running, and stopped when the engine stopped. This meant that the radiator was having air drawn through it at the same rate in freezing cold conditions as it was on a hot day, and when you parked the car, the radiator basically cooked because it had no airflow while it was cooling down. So nowadays, the radiator fan is electric and is activated by a temperature sensor in the coolant. When the temperature gets above a certain level, the fan comes on and because it's electric, this can happen even once you've stopped the engine. This is why sometimes on a hot day, you can park up, turn off, and hear the radiator fan still going. It's also the reason there are big stickers around it in the engine bay because if you park and open the hood to go and start messing with something, the fan might still come on and neatly separate you from your fingers.

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The cabin heater . Most water-cooled car engines actually have a second, smaller radiator that the coolant is allowed to flow through all the time for in-car heating. It's a small heat-exchanger in the air vent system. When you select warm air with the heater controls, you will either be allowing the coolant to flow through that radiator via an inline valve in the cooling system (the old way of doing it) or moving a flap to allow the warm air already coming off that radiator to mix in with the cold air from outside. It's all these combinations and permutations of plumbing in a water-cooled engine that make it so relatively complex. The rendering below shows the basic elements a water-cooled engine.

Overheating on a snow day :

Overheating on a snow day If you live anywhere where it snows a lot, you'll have seen hundreds of motorists stranded at the side of the road, hood up, with steam pouring out of their radiators on the worst weather days - when it's snowing hard. It's counterintuitive at first - surely on the coldest, snowiest day of the year, the last thing you'd need to worry about was engine cooling? Well - sort of. If you're going on a long-distance drive - hours on end on the motorway, you probably need to consider covering part of your radiator so it doesn't get too much cold air - otherwise your engine will never quite get hot. That's rare though

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