Coolant needs to be changed too.  Not as often as your oil does, but still, you will need to change or “flush” the coolant in your car.

Coolant needs to be flushed because it breaks down over the years and then loses the ability to serve its purpose of maintaining optimum temperature of the engine and preventing corrosion.  Dirt and rust particles are floating inside the coolant which can clog your radiator or heater core.  Clogs in the radiator will cause your car to overheat.  A clog in the heater core will prevent heat from getting into the car.  A heater core replacement is a very expensive repair, like $600-$900 expensive.  All to have some heat.  Yikes!

In a coolant or radiator flush, all of the old coolant is drained or flushed out and new clean efficient coolant is added in.  So, how often should you get a coolant flush?

It is best to follow your owner’s manual.  Each car has its own maintenance schedule and your owner’s manual will tell you when in miles or month/years to have your coolant flushed.

Here’s a rule of thumb.  Factory coolant or coolant that was added to the car when it was built should be drained by 100,000 miles if not before.  After 100,000 miles, it should be done every 3 years to keep your engine running at it’s best!


1. Radiator

Radiator is an iron-shaped composers used to cool coolant. The working principle of the radiator is to move the temperature from water to free air.

In a radiator will be encountered some parts like

Upper tank, is a tank to hold hot water or coolant from the engine.
Lower tank, is a tank to hold coolant that has been cooled and ready to be sent back to the engine.

The radiator core, is a flat-shaped channel that connects upper tank and lower tank space. The number of cores determines how much cooling power a radiator can carry.
The radiator fin, is a thin zinc formed between several cores on the radiator surface. This fins are used as heat receivers from cores while releasing heat into the air that passes through them.


The radiator works by utilizing the airflow passing through the radiator fins. This is the Mechanism, coolant that have hot temperature will be channeled to the radiator core. At here the heat will move to the core radiator and directly channeled to the radiator fin, because both of these materials are conductor. When there is air through the fins then the heat will move into the airflow.

2. The Radiator Cap 

The radiator cap serves as the cover of the upper tank radiator while keeping the air pressure inside the cooling system. This lid construction is not like a bottle cap or other lid, because there is a pressure regulating mechanism then there are other parts inside this lid.

The main part of radiator cap is a spring that pushes a valve downward. In a normal position, this spring will push the valve so that the valve can close the radiator duct. While the pressure inside the radiator increases, the pressure will fight the spring and cause the valve openned. Eventually the pressurized air comes out of the radiator and the pressure inside radiator becomes more stable.

The air pressure inside the cooling system may change due to the fact that the coolant temperature. The higher the temperature, the further water will evaporate. It has an effect to increase the air pressure within the system.

3. Radiator hoses

The function of radiator hoses are to supply radiator coolant from the engine to the radiator and back to the engine. Although its function is only channeling the coolant, this parts can not be underestimated.

The radiator hoses are required to be flexible but it must hold the coolant that have boiling temperature. Therefore, the radiator hose is made of special rubber which is designed to survive at high temperature but it flexible too.

There are about three types of hoses in the cooling system, namely;

Radiator input hose, is a radiator input hose that channels high temperature coolant from the engine.
Radiator Outlet hose, is a radiator output hose that carries low-temperature coolant to be supplied back to the water jacket on the engine.
By pass hose, this hose becomes a divider hose to several components at once. As to be supplied to the reservoir tank or heater.


4. Thermostat

Thermostat is a part that have function like valve. This valve will close and open the port between water jacket and high temperature radiator hose. It works to speed up the engine to get the working temperature.

Thermostat works with close and opening the chanel of water jacket to the output chanel in the radiator hose. When the engine temperature is low, thermostat is fully closed. That makes closed coolant circulation inside the water jacket. This circulation will faster engine temperature increasing, because heat from combustion chamber is circulate by coolant in all of engine part.


But when the working engine temperature reached (± 80 degrees C ) thermostat will slowly open. And the coolant automatically circulated outside to the radiator. The thermostat works automatically by utilizing a special wax that reacts to the temperature that affects it. But some thermostat using electric motor to open and close the valve.

5. Water jacket

Water shell or more familiarly known as water jacket serves as a place to absorb engine heat evenly. The name of the water jacket is just a term that leads to the water channel around the engine.

The chanels are fill wit coolant and it shaped like a jacket to the cylinder block, so that it called as water jacket. When the engine is running, the heat generated by the combustion. It will increase the engine block temperature and the cylinder head.

Since there is coolant flowing in this channel, the heat will also flow along the coolant stream toward the radiator for cooling.

6. Reservoir tanks

This tube serves to store evaporative cooling water. When the engine is in high temperatures, the coolant will evaporate and result in increased air pressure within the system.

To stabilize the air pressure, the evaporated coolant will be channeled into a tube through the radiator cap. In this tube, moisture will be condensed again to become a liquid.

The transformed vapor in the reservoir can be re-channeled into the cooling system when the pressure inside the system is vacuumed. This will prevent the reduction of coolant insde the system.

7. Cooling fan

The cooling fan works to take down the radiator temperatures. The working principle of cooling fan is by flowing the air from outside through radiator fins. There are two kinds of cooling fan, is

Convetional Cooling Fan, the working of this type is following the engine. So when the engine running on low RPM, the fan will rotating on low RPM too. This is happening because, the fan driven by engine pulley by v belt.
Electric coolong fan, second type there is more efficient fan. The electric fan work by electric curent that flow through motor fan. The fan work only when the coolant temperature above the engine working temperatures.


8. Water pump

The water pump is only have one function, is to circulate the coolant in order to move inside the cooling channel. The water pump is generally located inside the water jacket, when the thermostat closes this pump will cause a water flow in the water jacket that helps flatten the engine heat.

When the thermostat is open, there are coolant flow from the water jacket to the radiator for decrease its temperature. Same with cooling fan, there are two type of water pump. Conventional versions driven by engine power and electric versions powered by electric current.

9. Thermometer

Thermometer is used to measure the coolant temperature. Later results from these measurements will be shown to the dashboard of the car. But in modern cars, the existence of this thermometer has been replaced by ECT sensors.

10. Engine heat indicator-Tempature Sensor


It is still incorporated in the thermometer to find out how much the engine coolant temperature are. The purpose of these two components is to prevent the engine from overheating, by showing realtime coolant temperature in the display info panel on the dashboard then the driver will know if the cooling system is malfunctioning.