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Brice Thomas Radiators - How a Radiator Works

The radiator is one of the most vital components of a vehicle's cooling system. Being a type of heat exchanger, a radiator's purpose is to release the heat that the coolant has removed from the engine into the air allowing the coolant to pull additional heat from the engine. That sounds simple enough, but how does that happen exactly? Let's take a look at the flow of coolant through the cooling system and what transpires when the coolant enters the radiator.


Your engine is designed to work within a certain temperature range, typically 200° to 250° F. At this temp, the engine is able to fully combust fuel which increases fuel efficiency, the engine oil is thin enough to provide the ideal amount of lubrication, and the wear on metal parts is reduced. Below this range, fuel is wasted, emissions are increased, and the engine experiences increased wear and tear. Above this range you run the risk of significant damage to the engine including having the engine seize up when the pistons fuse to the cylinders, ruining the engine. Coolant is circulated through the engine to keep it within this ideal temperature range.

Coolant Path

Most of the engine block is hollow and filled with coolant. The water pump circulates the coolant through the engine block and the rest of the cooling system. When the engine is first cranked, the thermostat is closed which prevents the coolant from reaching the radiator. Instead, the coolant is routed back through the water pump and back into the engine without being cooled. This allows the engine to heat up quickly and reach its ideal temp. Once the temperature is raised, the thermostat opens allowing coolant to flow to the radiator and then back to the pump. (For a more in depth look at the importance of your thermostat, check out our “Is a Vehicle Thermostat Necessary?” article.) The coolant passes through the radiator and releases much of the heat it has absorbed into the air. How this happens is all part of the radiator’s design.

Radiator Design

A standard radiator consists of the following components:

  • Two tanks
  • The core, which is made from:
    • Headers
    • Tubes
    • Fins
  • Mounting Brackets

A radiator’s core is made from alternating rows of fins and tubes which are attached to headers. The fins are connected to the tubes and the tubes are joined to the headers through a process called brazing. In brazing, a filler metal is used to join the pieces together. This is a similar process as soldering except that the filler metal used has a higher melting point than the filler metal used to solder. The brazing process creates a more durable bond than soldering would given that the radiator will be heated to high temperatures by the the coolant coming from the engine. Thus we have the radiator core.

The headers not only hold the tubes and fins in place but also provide the mounting surface for the radiator tanks. Once the tanks are attached to the core and the mounting brackets are attached to the whole unit, you have a radiator that’s ready for operation. When the radiator is in use, coolant flows into the tanks and through the tubes from one side of the radiator to the other. As the coolant travels, heat transfers from the hot coolant to the cooler tubes and is dissipated into the air by the fins. Agitators may be included inside the radiator tubes to ensure the coolant releases as much heat as possible. Without agitators, the coolant touching the tube would cool down, but the coolant in the middle would retain its heat. If hot coolant returns to the engine it can’t absorb as much heat which will increase the risk of engine damage.

That is how a radiator dissipates the heat from the engine and into the air. Without it, our engines would quickly be of no use. If you feel like your radiator or cooling system is not performing like it should, give our staff at a call at 1-800-223-4299. We’ll be happy to help advise you on what steps you need to take to ensure your vehicle is performing at its peak.



Brice Thomas Radiator specializes in the manufacturing of Custom, all aluminum, radiators for the antique, performance, truck and industrial radiator market. With over 50 years experience in the radiator business, we have developed a tremendous amount of knowledge in the heat transfer business. Brice Thomas Radiator has been in business since 1956 and for years we specialized in the repair and re- core of copper/brass radiators. Now, Brice Thomas owns and operates an all aluminum brazing facility in Gadsden, Alabama. All of our radiators are TIG welded to give you that clean, neat custom look that you are looking for. We manufacture the cores, tanks, and brackets all in the USA!!!! 


For more info go to our website or give us a call at 1-800-223-4299