How to Choose a Radiator Fan

The car radiator fan helps to regulate engine temperature and prevent overheating. The fan is one of the most challenging parts to buy, though, with its many different designs and prices. Engine cooling need also vary across vehicles which further complicates the selection process. If you’re about to buy a radiator fan, read on for useful tips on how to find the right type for your car and engine. Let’s start by looking at what a cooling fan does and the different types available today.

What’s the Radiator Fan Purpose in your Car?

A vehicle engine generates tremendous amounts of heat when running. This heat must dissipate or the engine temperature will rise to dangerous levels. To remove the heat, most cars use a water cooling system. The system consists of channels to circulate coolant around the engine and a radiator to cool the heated coolant.

The radiator consists of tubes carrying hot coolant from the engine. It’s positioned behind the grille so that the air streaming in will cause the coolant to cool. When your car is moving at a considerable speed (over 25mph) the air blowing through the grille effectively takes away heat. But not so when you stop for some time or when stuck in slow-moving traffic.

During such times, the airflow to cool the radiator must come from somewhere. The device that performs the function is called the radiator cooling fan. The fan rotates to produce airflow when there’s little to no air rushing through the grille, thereby helping to prevent the engine from overheating.

the radiator fan blows air through the radiator core

The radiator fan assembly comprises a 12V DC motor and fan blades. The motor’s function is to produce the rotational force that spins the fan blades. In most radiator fan assemblies today, a shroud is added to direct air toward the radiator and improve airflow efficiency.

Automotive radiator fans are powered in by either the engine crankshaft or an electric motor. Fans that run off the engine are commonly used in older vehicles, while modern cars used electric fans. If you observe different engine cooling fans, you will easily notice a difference in the design of blades. Some are curved while others are straight.

Radiator fans are usually mounted in the space between the engine and radiator. In some cars, the fan is installed between the radiator and grille. There are different reasons for that but the most important is the availability of space. To help you understand the different options when buying a radiator fan, the versions used in different cars are explained below.

Radiator Fan Types

Radiator cooling fans or engine cooling fans come in a wide range of styles, sizes, and more. When buying the component, it’s necessary that you’re aware of these fan types and the advantages or disadvantages of every option. With the information, you will easily find the best one for your type of car, or one that suits specific engine needs. The car radiator options available classified into the following types.

Based on the Method of Operation

a mechanical radiator fan showing the clutch in the middle

Mechanical radiator fanthis refers to the engine-driven type of fan. You will usually find it mounted on the car’s water pump pulley. Its operation is controlled by a thermally operated clutch. When the coolant temperature rises, the thermal mechanism causes the fan to engage and vice versa. Some mechanical fans use flexible blades instead of clutch. The blades flatten at higher rpm to increase airflow and the opposite when temperature lowers.

Mechanical blades take a lot of space since they have to mount on a pulley and link to a drive belt. They also only rotate when the engine is running, which makes them less effective at lower rpm. They also reduce the engine horsepower although only slightly. These types of fans are mostly used on older vehicles.

Electric radiator fan- this is the modern type of cooling fan that does not need the engine to run. Instead, it’s powered by a vehicle’s electrical system. The fan contains an electric motor that spins to rotate the fan assembly. Most electric fans today operate electronically, with a control module and sensors to determine when it comes on and when it stops.

Electric fans are more effective than the mechanical types, plus they do not rob the engine of horsepower. You can use them even when the engine is not running, which is one of their biggest advantages. Their speed is also more controllable to match the engine cooling requirements.

Based on Blade Style

Curved blade radiator fan

Curved radiator fan- this is the name given to a cooling fan that uses curved blades. This blade style reduces the level of noise when the fan is working. The only disadvantage is that despite the quite operation, curved blades do not move a lot of air. As a result, these fan types do not suit highly demanding engines when it comes to cooling requirements.

Straight Blade radiator fanthe blades are straight in this type of fan. Straight blades generate a lot of noise. Their main advantage lies in the ability to move a lot of air per minute or what’s commonly called CFM rating. Straight blade radiator fans and mostly used in with large or demanding engines where the rate of cooling is more important than quiet operation.

Based on Setup

dual radiator fans

Dual radiator fansthis configuration consists of two cooling fans working together. Dual cooling fans produce a stronger airflow, which makes them more effective. When one of them fails, the working fan helps to cool the engine until you can get the problem fixed. The dual setup is normally possible when using electric fan due to their compact nature. Also, when there’s enough room for their installation.

Single radiator fan- most cars use a single cooling fan. In this setup, only one fan provides the flow of air needed to cool the radiator. A single cooling fan is commonly used in mechanical fan systems. it also mostly suits small and medium or slightly modified engines. Larger or heavily modified engines may require a stronger airflow- and more than one fan.

car radiator fans come in different designs

How to Choose a Radiator Fan for your Car

As we have seen, there are many variations of the radiator cooling fan today. Many motorists also modify car engines and change their cooling requirements. When selecting a radiator fan, weigh the available options against the needs of your specific engine. The tips below will help you find the best radiator fan for your situation.

Mechanical or Electric?

The first question to ask yourself is whether you need a mechanical or electric radiator cooling fan. Mechanical fans are further classified as clutch or flex type. Generally, you should go for a cooling fan that replaces the older one, unless if considering to upgrade to a better fan. Choose a mechanical fan for stock or slightly modified engine and electric for high horsepower or highly modified engine.

Single or Dual Fan?

Most engines will do with a single fan. If you have installed a larger engine, added a turbo charger or supercharger and other modifications, a dual setup is better than a single fan. You need more air, which one fan may not produce. If considering a dual cooling fan configuration, ensure you have enough space. Some car will only have enough room for one fan. Dual configurations are also normally possible with electric radiator fans.

Push or Puller Fan?

A radiator fan is usually either a push or puller type. Puller fans are better in many ways. They do not obstruct incoming air when the vehicle is moving, which means more air blowing through the radiator core. They also provide a more effective airflow owing to their position behind the radiator. But you cannot always install a puller fan in your car despite its many advantages. It depends on the availability of space. Ensure you have room between the radiator and the engine before you can consider installing one.

Straight Blade or Curved Blades?

One of the main differences in the design of engine cooling is in the style of blades. The blades are normally either straight or curved. Straight blades move more air than curved blades. However, they produce a lot of noise. The curved types are quieter but move less air. When choosing the type of blades, determine what’s more important for your car between airflow and quiet operation. If your engine cooling needs are higher, go for the straight blade. If not, you want to choose the quiet working of the curved blade cooling fan.

Shroud or no Shroud

Radiator fans come with either a shroud integrated or without. You can also install one. Shrouded fans offer more benefits. They move air through the radiator core more efficiently, without loss. When the fan contains no shroud, the air movement is less efficient and often leading to an overheated engine. Shrouded fan are more expensive than those without one. Be prepared to pay more for the additional benefits.


The radiator fan CFM refers to the amount of air that it can move in a minute (CFM stands for cubic feet per minute). You should select the CFM rating that matches your engine needs. Doing so will help to ensure you do not encounter overheating problems that could lead to costly repair and, in the worst of cases, engine replacement. The recommended CFM ratings for different engine sizes are indicated below.

1250 CFM- 4 cylinder engine

2000 CFM- 6 cylinder engine

2500 CFM – 8 cylinder engine

Besides engine size, there are other reasons to use a radiator fan with high CFM rating. These include when you have installed a turbo charger or super charger to increase engine power and other modifications. Such engines need more air to cool them and a fan that can pull or push large amounts of air through the radiator core than before.

Cooling Fan Diameter

It’s also important that you consider the diameter of the radiator fan or, in other words, the cooling fan size. The diameter of the fan affects its ability to move air, with larger fans providing a better cooling effect. When using a large fan, your car engine will idle for long and not overheat. You will be able to drive in slow traffic without the engine temperature rising or drive over long distances and not damage the engine. Always choose a fan that covers most of the radiator surface but allow enough clearance so the blades do not touch anything.

Current Draw

This refers to the fan’s current rating. Radiator fans are usually rated by the amount of current they operate on. A higher current means a more powerful fan- and better cooling performance. If you’re looking for a fan to help cool a large or modified engine, choose a fan with a high enough current rating or amp draw. This will often be indicated by the manufacture among the specifications and features of the particular fan.

Other Features

The main factors to consider are listed above. However, these are not the only considerations. To buy a good quality cooling fan for your engine, check specific features such as the construction, materials used, and more. Go for sealed fans that will not allow dirt and moisture in. Check the materials used to make the fan assembly- and coatings if any. These are among the things that increase the device’s useful service life.

While still on the buying process of a cooling fan, it’s advisable that you avoid purchasing rebuilt units. Although the prices may look attractive, the lifespan is not guaranteed and you may find yourself shopping for a new fan sooner than you thought. The cost of radiator fans varies widely also, so do not be surprised that price tags are different for different models.

A fan that comes with an integrated thermostat, for example, will be pricier than one that does not. Electric fans are also generally more costly than the mechanical types. If you buy a fan that has a shroud, you will pay more for the extra feature. These higher radiator fan prices are justified, given the better performance and durability you will get from using the pricier types. Only make sure the manufacturer is reputable for making quality parts.


Choosing a radiator fan for your particular engine is no easy task. There are many things to consider and many decisions to make. But with the right information, the process can be simple and straightforward. This article should help you find the most suitable engine fan for your car. To avoid compatibility problems, you might want to choose an OEM model based on your car details such as make, model and year of manufacture. For better cooling performance when you have a different or modified engine, consider the aftermarket types. These allow you to choose from a wide range of designs and features. .

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