Sparesbox Blog

What is a Radiator?

By James Andrew

Tue Sep 29 2015

What is a Radiator?

A Radiators are an integral part in the Cooling System of all water-cooled vehicles. It is effectively a heat sink or heat exchanger. The coolant is cycled through your engine by your water pump, absorbing the heat dissipated by your engine which is then passed through your radiator.

A Radiator is made of three main parts including two tanks which typically come as a top tank and a bottom tank. Though sometimes the tanks can be located on the sides like the Radiator in the image below. The Radiator “Core” is the third main component.

Radiators width=


Single Pass vs. Double Pass Radiators

In the past, Radiators were what is referred to as “Single Pass”. Hot coolant enters the Radiator from the top (because its easier to allow the water to flow downwards than force it upwards almost vertically) and exited at the bottom on the opposite side.

Single Pass vs. Double Pass Radiators


Nowadays we have whats referred to as Double Pass Radiators. The hot coolant enters at the top of one corner, and is passed through the cores twice before exiting. This makes the most use of the available surface area of the Radiator.

A Radiator is all about surface area. As heat is dissipated through the metal of the Radiator, it is cooled by the air passing over it as you drive. The more surface area in contact with the cool air, the more effective it will be. This is the reason for the hundreds of small fins in the Radiator Core – it’s all about maximising surface area.

Radiator Fins


Modern Coolants have very effective agents added to them to stop corrosion of the Radiator and Engine Components. If the coolant is not changed regularly, it can go off and become ineffective. Any resulting corrosion is liable to become clogged in the Radiator Core. As you can imagine, the results of this can be disastrous. It always pays to keep your coolant in check and have the system flushed properly when changed.