How to Identify Cooling System Parts

A number of different cooling system parts make up the entire cooling system in your vehicle. The basic job of the different cooling system parts is to push coolant through the engine to ensure it runs properly without overheating. To understand how the cooling system works, you need to be able to identify the various cooling system parts.


The radiator is located at the front of the engine compartment, just behind the grille. The core of the radiator is aluminum. Its job is to disperse the heat from the coolant and the engine into the air. There’s a hose at the top of the radiator, which draws the coolant into the radiator. The hose at the bottom sends coolant out.

Radiator Fan

The radiator fan will either be behind or beside the radiator. Its job is to keep the radiator cool, and also to circulate the air. It’s especially useful when you’re at a stop, or driving very slowly; the fan will kick in and stop the engine overheating. The car’s computer controls when the fan turns on and off.


Your coolant reservoir is where you add the coolant to the engine. It will be in different places in different vehicles. You need to check it regularly, especially in warm weather, and top off as needed. If you often need to top it off, however, this can be an indication of serious problems.

Pressure Cap

The pressure cap used to be on top of the radiator, but these days it’s generally to the side. It’s there to stop the pressure becoming too high. If the pressure in the system passes that point, the cap will spring open to release the pressure.

Water Pump

You rely on the water pump to keep pushing the coolant through the system. It’s usually driven by a belt, although which belt will vary by make. It’s next to the engine block, with just a gasket between pump and block.


You won’t see the thermostat when you open the hood, but it performs a vital role among the cooling system parts. It makes sure that the coolant remains at the correct operating temperature, and is in the top front of the engine block, where the upper radiator hose connects to it.


There are a number of hoses involved in the cooling system of a vehicle. The upper and lower radiator hoses are the biggest in diameter and the most important, but you’ll also see smaller hoses, generally 1 inch in diameter, which run to the heater core. These take hot coolant, which is used to heat the inside of your car, and carry it back when cool. The final, small hose runs from the reservoir to the radiator.

Heater Core

The remaining component of the cooling system parts is the heater core. This is at the back of the engine compartment, and looks like a much smaller version of the radiator, with a fan in front of it. When you switch on the heat in your car, this fan blows the hot air through the ducts.