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The typical cooling system is made up of a number of parts. The following is a list of these parts:
The following is a diagram of a typical cooling system on today's vehicles:
You may find it necessary to refer to this diagram periodically as you read through the rest of the information to follow.
GENERAL OPERATION AND PURPOSE OF A COOLING SYSTEM
The basic purpose of the cooling system is of course to do just that; cool the engine and it's parts. The reason that this system is required is quite simple. The common engine in today's vehicles works through internal combustion and thus creates temperatures of up to 4,000 deg. F. When fuel is burned in an internal combustion engine some of it is turned into power to propell the vehicle, some of it will go out the exhaust pipe as wasted and some of it is turned into heat energy. Two types of cooling systems exist in today's vehicles. One is based on air cooling and the other on water (antifreeze) cooling. Air cooled systems are more commonly found on motor bikes, lawn mowers and air planes. Most of todays passenger cars and trucks are cooled with water (antifreeze) cooling systems. The diagram above shows a typical water (antifreeze) cooling system. In a system such as the one shown above the water (antifreeze) is cycled through the system by means of the water pump. As the water (antifreeze) is pushed through the system it is cooled by the radiator and then introduced back into the system in order to disepate further heat. In this article it is our intent to give you some details about each of the components in the cooling system and then discuss further how they operate together. It is not our intent to become overly technical as this article is being written to give you a basic understanding of the function of a cooling system rather than details on how to diagnose it or repair it.
DESCRIPTIONS OF PARTS WITHIN YOUR COOLING SYSTEM
Your radiator is a container made up of fine tubes that carry the coolant (antifreeze) over a large surface area at the front of the vehicle that wind passes through. The general idea of this is that it will have time to cool off as it passes through these tubes so that it can dissipate more heat once it is introduced back into the engine. The coolant follows a steady cycle of doing this same job over and over again.........
The water pump in your vehicle is like any other kind of pump that you might have seen or be able to imagine. The sole purpose of the water pump is to make the coolant flow from the block of the engine into the radiator where it is cooled and then back into the engine so that it can cool the internal and external components as well as the engine oil. It is through the constant flow of the coolant that it looses and regains heat from the engine. The following is a quick definition of a water pump taken from about.com. The accompanying picture (also from about.com) shows the inside of the water pump revealing the impellers. These impellers are what move the coolant through the pump. Definition: A small impeller-like pump that circulates coolant through the engine's cooling system. The water pump is mounted on the engine and is driven by the fan belt, alternator belt or overhead cam timing belt. The pump shaft has a large bearing and seal, which after 40,000 miles or so usually starts to leak. The pump can be replaced with a new or rebuilt unit, but the degree of difficulty varies, depending on pump accessibility.
The expansion or over flow tank in your vehicle holds excess coolant from the radiator as the system heats up and cools down. You will find that most expansion tanks have two lines drawn on the exterior of the tank and are made of a plastic that is clear enough to see through. The reason for this is to be able to tell what level the antifreeze is at. One of these lines will be marked as full hot and the other marked as full cold. The purpose of this is obviously to allow proper filling of the tank. When the coolant becomes hot it expands and will move to the hot mark on the tank. As it cools off it will contract and move back to the cold mark.
Your radiator cap is designed to hold a certain amount of pressure. By keeping the coolant under pressure it raises the boiling point. Without the radiator cap sealing the system and allowing it to pressurize to 15psi the coolant boiling point is reduced to 226°F. Sealed to 15 psi, it will not boil before 265°F. This difference is what allows for hotter running in the summer time. Your vehicle will run more efficiently and perform better when running at the proper operating temperature. When your vehicle is in for its semi-annual cooling system flush the radiator cap would be tested.
Radiator hoses are usually referred to as the upper and the lower radiator hoses. These hoses have a fairly limited and simply task. They simply carry the antifreeze to and from the radiator as required to cool the engine. The normal flow is from the lower hose to the water pump, through the cooling passages in the engine, and back through the thermostat to the upper hose and then into the radiator. Radiator hoses are made of a rubber compound that will withstand the high temperatures of coolant flowing through it along with the pressure created by the cooling system.
The thermostats main function is to keep the engine running at proper operating temperature. It is also responsible for redirecting the coolant to the heater core in order to produce heat inside of the vehicle as well as to speed up the process of getting the engie to operating temperature. Once the coolant has reached normal operating temperature it is then directed to the radiator as the thermostat opens. This is when the cooling process starts. Once the antifreeze gets below normal operating temperature from flowing through the radiator the thermostat will close again. This same process is simply repeated over and over again as the antifreeze heats up and cools down.
Your heater core is just a miniature version of your radiator. It is typically located behind the dash on the passenger side but location is dependant on the vehicle make, model and year. The purpose of the heater core is to produce heat inside of the vehicle. Through a number of tubes, hoses and vents the antifreeze is pushed to the heater core and then back to the radiator. The heating system has a fan called a blower motor that blows air over the heater core and back into the passenger compartment. This air is heated as it passes over the heater core in order to create heat inside the vehicle.
Cooling fans come in two basic types as listed below:
Electric cooling fans are controlled by a coolant temperature sensor and are driven by an electric motor. The advantage of an electric fan versus a mechanical or belt driven fan is that the fan can keep running after the engine has been turned off. This allows for better cooling of the engine when shut down in a hot state. The coolant temperature sensor is located in different places on different vehicles but the one common element is that a probe sits into the coolant in order to get a proper temperature reading. Then the coolant reaches a point just above operating temperature the fan is commanded to come on and when it drops below operating temperature that fan is commanded to turn off.
Belt driven cooling fans or mechanical fans as they are often referred to are driven by the engine itself. They are driven by a clutch that operates on temperature. As the clutch gets hot it engages the fan and as it cools off it disengages the fan. This is not nearly as accurate for operating temperature as an electric fan but serves the same purpose.
Belts operate things such as your water pump and or cooling fan. A vast majority of vehicles today have only one belt that is referred to as a serpentine belt. This belt now drives a number of components such as your water pump, power steering, alternator, air conditioning compressor and or any other accessories in the vehicle.
Oil cooler lines can refer to two different types of lines. Engine oil cooler lines as well as Transmission oil cooler lines exist on most vehicles. The idea of these lines is the cool these fluids while they are kept out of their operating environment. Although every passenger vehicle today has a transmission oil cooler not all have an engine oil cooler. The oil cooler is a miniature radiator that can be found mounted along side the radiator. The oil cooler lines will carry fluid from the engine or transmission to their respective coolers and then back again to that component after having been cooled off. |
