All You Ever Wanted To Know About Radiators

In automotive language, a radiator is the heat exchanger used to transfer heat from the engine to the atmosphere. A typical automobile actually has several radiators on board, though most of them will not be called that. The heater core in your passenger cabin for heating the interior of your car is a small radiator. If your vehicle has an oil cooler, it is another type of radiator. 

Specifically, though, the term "radiator" typically describes the large unit that cools the engine's coolant.

Radiators themselves are simple devices that have no moving parts and work on very simple physical principles. They are an integral part of the engine's overall cooling system.

How the Cooling System Works

How a Radiator Works

The cooling system in a typical engine is a simple circuit of coolant flowing through the engine's block. Coolant is constantly inside the engine, being circulated by a water pump that moves it through the engine, top to bottom, forward to back - you can learn more about your coolant here. When the engine is cool, the coolant flows in a circle without leaving the engine core. When the engine heats up, the water is diverted by a valve made to detect heat (thermostats) into the radiator for cooling. Then it returns to the engine to continue circulation. Another valve allows the hot coolant to be sent through the heater core in the passenger cabin before returning it to the engine.

This circuit continues every time the engine runs, so long as the water pump functions. This is why even on today's sophisticated, modern engines with all of their electronics, the water pump is nearly always powered mechanically rather than electronically. It is integral to the continued operation of the engine. If they pump fails, the engine will overheat, and could be damaged beyond repair. 

How the Radiator Works

Radiator hose replacement

The radiator in this circuit is the most visible and important part of the engine's cooling system. When the coolant in the engine becomes hot, it causes the thermostat to open its valve, letting the coolant out and into the top of the radiator. From there, it circulates down in a serpentine fashion, right to left, to the bottom of the radiator, where it returns to the engine via the water pump inlet.

As the water moves down through the radiator, it passes through small-diameter pipes (usually made of copper) that are surrounded by and connected to thin aluminum fins. Aluminum is a high-efficiency thermal conductor, so the heat from the water is quickly pulled off as ambient, cooler air passes over the fins and "pulls" it away. This cools the coolant, which is then sent back into the engine to pick up more heat and repeat the process.

Although radiators are simple, they can leak or become clogged. The thermostats that control the water flow into and out of them can also malfunction. When a vehicle is scrapped for parts, the radiator is often pulled so the copper and aluminum can be recycled.

Identifying Radiator Problems

There are several signs that a radiator may be failing and in need of replacement. This includes:

Coolant Leaks

There might be coolant leaking if the radiator has corrosion or cracking from age. The radiator could also be leaking from damage caused by impact from road debris or a collision. The radiator won't be able to sufficiently cool the engine due to a loss of coolant. 

Buildup Of Deposits

Over time, the radiator may become restricted with sludge, mineral deposits, or oil from an engine gasket failure. The coolant will likely be discolored from contaminants. When the radiator becomes restricted from these buildups, it can no longer cool the engine properly.  

Engine Overheating

As mentioned, coolant leaks or restrictions in the radiator will cause the engine to overheat. The cooling fins on the outside of the radiator may also get damaged over time. A buildup of dirt and debris in the cooling fins will restrict airflow across the radiator and cause overheating. Sometimes the radiator can be removed and cleaned to restore cooling efficiency. For more information on engine overheating, check out our blog post on how to Figure Out Why Your Toyota Is Overheating.

The Importance Of Radiator Hoses

Toyots radiator hose

The rubber radiator hoses are the most vulnerable part of the cooling system. The radiator only works as well as the hoses transporting coolant between it and the engine. Swollen, collapsed, or leaking radiator hoses will prevent the radiator from cooling the engine sufficiently. Learn more about radiator hoses in our complete Toyota Radiator Hose Buyer's Guide.

You Can Count On Olathe Toyota Parts Center 

If you do have questions or concerns about your Toyota radiator, or need radiator parts, we can help. Rest assured that when you buy from Olathe Toyota Parts Center you'll get:

  • A large selection of radiators and radiator parts for your Toyota vehicle to choose from. 
  • All OEM parts that are backed by the standard Toyota 12-month, unlimited miles warranty.
  • Knowledgable support from our team. If you have questions we’re here to help. Please feel free to contact us!