What Do Vehicle Cooling Radiators Do?
A vehicle radiator is the heat exchanger that sends part of the heat produced by the engine out through the coolant and keeps the engine at a suitable operating temperature. This article summarizes the cooling circuit in cars and commercial vehicles, the radiator's place in it, and the differences between parts that look similar.
How does the engine cooling circuit work?
Part of the heat generated during combustion passes into the engine block and the cylinder head. The water pump circulates coolant through passages inside the engine; the fluid absorbs heat and flows to the radiator. In the radiator, air passing between the thin fins draws heat out of the fluid, and the cooled fluid returns to the engine.
The circuit is closed and pressurized. The radiator cap holds system pressure at a set value, which helps raise the boiling point of the coolant. Because the cap rating varies from vehicle to vehicle, go by the manufacturer's specifications.
Main parts of the circuit
- Radiator: The core that transfers heat from the coolant to the air.
- Coolant: Carries the heat; antifreeze additives protect against freezing and corrosion.
- Thermostat: Restricts coolant flow to the radiator while the engine is cold and opens as the engine warms up. This way the engine reaches operating temperature quickly.
- Fan: Moves air through the radiator when the vehicle is slow or stationary.
- Water pump and hoses: Keep the coolant circulating.
How do the thermostat and fan work together?
On a cold engine the thermostat is closed; the coolant circulates only inside the engine, and the engine reaches operating temperature in a short time. As the temperature rises, the thermostat opens and the coolant is directed to the radiator. When the vehicle is moving fast enough, air flows through the radiator on its own; in traffic or on a slow climb, the fan takes over this job.
The fan can be driven mechanically by the engine or by an electric motor, depending on the vehicle design. A stuck thermostat or a fan that does not run can cause overheating even if the radiator is sound. For that reason, when troubleshooting, think of the circuit as a whole instead of looking at parts one by one.
Cars versus commercial vehicles
Commercial vehicles generally run under higher loads, for longer periods and often on slopes or at low speed, so their cooling systems are stressed more. The radiator and fan should be selected with a reasonable heat rejection margin. An aluminum core is a common choice because of its light weight and heat conduction; for details, see our article on why aluminum radiators.
How do an intercooler and an A/C radiator differ from a radiator?
All three are heat exchangers, but they work with different fluids:
| Part | What does it cool? | Function |
|---|---|---|
| Engine radiator | Engine coolant | Keeps the engine at operating temperature |
| Intercooler | Air compressed by the turbo | Cools the air going to the engine |
| A/C radiator (condenser) | A/C refrigerant | Rejects heat from the cabin cooling circuit |
These parts usually sit side by side at the front of the vehicle, so they can be confused with each other; there are also cases where one being clogged affects the others. Under the SAFKAN brand, Safkan offers water-cooling radiators, A/C radiators and intercoolers; you can see all product groups on our products page.
The type and mixing ratio of the coolant should also follow the vehicle manufacturer's recommendation; the wrong fluid can lead to corrosion and loss of heat transfer.
Warning signs and next step
A rising temperature gauge reading, a coolant level that keeps dropping, or a fan that runs unexpectedly can indicate a problem in the cooling circuit. In such cases, check the whole circuit instead of blaming a single part; for an overview of faults, our article on how to tell if a radiator is failing can serve as a guide.
To choose the right radiator for your vehicle, you need the make, model, engine type and the dimensions of the existing part. For product selection and technical information, reach us through the contact page.