Let’s take a look at the different components. The coolant is the liquid medium that is used to transfer the heat from the engine to the radiator. This substance is made of pure water and antifreeze and is composed of approximately a 50-50 mixture. There are several different types of coolant that are used by various manufacturers and it is important to use the correct type when adding coolant to a system. When quality coolant is used, the boiling point is raised while reducing the freezing point of the fluid to safe levels to prevent the substance from freezing when very cold temperatures are present. Care should be taken to never allow the coolant to freeze into a solid, which would likely cause major engine damage.
Water The water pump is the mechanism that forces the coolant through the engine, which carries the heat out to the radiator. There are several methods used to drive the water pump: the accessory drive belt, the timing belt, the timing chain, or an electric motor. The water pump has a limited life span and will need service if it fails because of leaks or a bad bearing. The pump will leak if the seal fails. Coolant will escape from the weep hole if the seal fails.
This chart shows the various colors and types of coolant that are available in the marketplace. Caution should be used to make sure that the correct coolant is used in each application. (Photo Courtesy
The water pump has an impeller that forces the coolant through the engine, heater core, and radiator. The water pump is driven by the accessory belt, timing belt, or timing
The water pump is an important part of the engine cooling system because it moves the coolant throughout the engine as well as through the heater core and the
Water pumps that are driven by the timing belt require more work and labor time to replace when they fail. It is wise to go ahead and replace the water pump during the timing belt replacement interval because it is driven by the timing belt and is easily replaced while the timing belt is
The accessory belt is a common way to drive the water pump on many engines. The drive belt tensioner holds constant pressure on the belt to prevent belt slippage. The belt must be removed along with the water pump pulley to gain access to the water pump
The thermostat performs a vital job for the cooling system by regulating the temperature of the engine. The thermostat blocks coolant flow leading to the radiator when the engine is below normal operating temperature. This allows the engine to build temperature to reach a level required for optimum efficiency and reduced emissions. The thermostat also contributes to the heating system to produce warm air
The thermostat uses a temperature-sensitive pellet or spring to regulate coolant flow in the engine. If a thermostat opens too soon or fails in the open position, then the engine will not warm up at the normal rate, which will reduce fuel economy as well as the performance of the heating
The thermostat is the mechanical temperature-regulating device that works to allow the engine to reach and maintain normal operating temperature. The thermostat operates by holding coolant in the engine until a specified temperature is reached and then it opens to allow the hot coolant to leave the engine and travel to the radiator. When the heated coolant exits the engine, cooler coolant is allowed to enter the engine, which helps the engine cool down. This process continues with the goal of keeping the engine at a predetermined temperature, which is generally about 180 to 200°F.
The radiator is the heat exchanger that is located in front of the vehicle. Hot coolant enters the radiator and it passes through the core while air passes over it, which allows the heat to be removed from the coolant. Radiators are available in downflow and crossflow designs as well as various dimensions and core thicknesses. The size variables of the radiator are dependent on the needs of the engine setup. The radiator cap is an important item that is used to seal the radiator from leaking. An interesting aspect of the radiator cap is that it allows the cooling system to build up pressure as the temperature rises. This design allows for the boiling point of the coolant to be raised, which helps prevent an overheating situation.
The bottom side of the thermostat is exposed to the heated coolant produced by the engine. A thermostat that is stuck closed will quickly cause the engine to overheat and likely boil the
The radiator is the big heat exchanger located in the front grille area of the vehicle. This crossflow radiator has the tanks located on each side of the core. Coolant enters at the top left side and then flows across the core area, releasing heat to the passing airflow until it gets to the tank on the right side. The coolant exits on the bottom left side when the thermostat opens to allow hot coolant to leave the engine and cooled coolant to enter the
This radiator is a downflow design that has the tanks located on the top and the bottom of the core assembly. Coolant enters at the top tank and then flows downward through the core area, releasing heat to the passing airflow until it gets to the bottom tank. The coolant exits the bottom tank when the thermostat opens to allow hot coolant to leave the engine while letting cooled coolant enter the
The cooling system is designed to allow the heated coolant to build pressure, and the radiator cap operates to allow this pressure to build up to specified levels before releasing to the reserve tank. This added cooling system pressure raises the boiling point of the coolant to help prevent the system from boiling over under high-load conditions. The radiator cap should never be removed while the engine is hot because the pressurized coolant could cause burns if it gets sprayed onto the person removing the
Hoses and Radiator hoses and heater hoses are used to connect the various parts of the engine cooling system. Many hoses are designed to have natural bends that allow for direction changes without causing the hose to crimp, which would impede the flow of coolant. The hoses are secured in place with hose clamps that apply pressure to prevent leaks. Hose clamps are available in several sizes and styles, and each one is unique in how it is serviced.
The cooling system hoses are often designed and manufactured with natural bends that allow safe and reliable routing through the engine compartment. The constant tension hose clamps provide long-lasting service without losing any strength or holding
The upper radiator hose connects to the upper intake area of this engine and is held in place with a constant tension hose clamp. This hose also has some plastic conduit installed around it to provide further protection from the heat in the engine
The heater hoses are connected to the heater core at the lower section of the firewall. The hoses are secured with constant tension hose clamps that will provide reliable sealing of the hose
Hose clamps come in many sizes to accommodate the varying sizes of hoses. Two of the most common styles of hose clamps are the threaded style and the constant tension style. A screwdriver or a socket can be used to adjust the threaded style, while pliers or special hose clamp pliers are used to remove and install the constant tension–style
Coolant Pipes and Many manufacturers are using coolant pipes in place of coolant hoses. These coolant pipes are typically made from light metals or plastic and are connected with various styles of coupling techniques. These coupling processes used by manufacturers allow for quick assembly when the vehicle is being put together. However, these quick coupling devices do not allow for reliable outcomes when it comes time for servicing them. It is recommended that the coupling devices be replaced when they are removed for any service operation.
Plastic quick-connect coupling joints are used on many cooling systems to connect hoses and pipes together. These types of coupling joints require service when the plastic gets brittle with
Constant tension hose clamp pliers make servicing this style of clamp quick and
Many manufacturers use coolant pipes to carry coolant to various parts of the engine. These coolant pipes use quick-connect couplings to connect to other parts of the engine. It is wise to replace these quick-connect coupling connectors when service is required to reduce the chance of leakage after the
Some plastic quick-connect fittings use a small snap ring to hold the fitting together. All of these plastic coolant fittings have a shorter life span due to the deterioration of the plastic over
This coolant hose is fitted with a plastic quick-connect fitting that is factory crimped onto the hose. This hose assembly will need to be replaced with a similar style unit that has a quick-connect
This heater core is made from copper and wrapped with an insulating foam to ensure that the duct box air must pass over the core so it can be heated
