Cooling fan (radiator fan) for your car

Engine temperature under control with the radiator fan

The radiator fan is a large blade wheel located directly behind the radiator. It prevents the engine from overheating. A malfunction can cause engine damage. Therefore, the radiator fan's function should regularly be checked, particularly in older cars.

Radiator fans: different types

A radiator fan has one task: supplying the radiator with air in order to cool it. The engine is cooled by the coolant, preventing the engine from overheating. A fan placed in front of the heat exchanger is a "blowing" fan. A "sucking" fan is located behind the heat exchanger. The sucking fan is more common, as it does not stand in the way of the heat exchanger's cooling air stream. Radiator fans differ mainly in drive. We discern:

• fans driven directly by the crankshaft
• electric fans

The radiator fan gets its name from its internal fluid coupling. It is an expensive component of complicated construction. According to its operational principle the fan switches on as soon as the engine has reached a specific temperature. The viscosity of the fluid in the coupling changes, switching on the fan. The advantage is mainly its great reliability. High costs and complicated installation are its disadvantages. The part is operated by a belt drive receiving rotational speed from a drive flange on the engine – generally the crankshaft. This can decrease engine's performance with 10 HP. This spare parts are used in BMW's, racing cars, offroad vehicles and many commercial vehicles. The electric fan is driven by a small electric motor. In addition to the motor, this type of fan requires a temperature sensor and an automatic switch. The electric fan's construction is much simpler, which makes it cheaper. The electric fan does not impair the engine's performance and is lighter. Its installation in the engine compartment is rather easy, which makes it suitable for other cooling functions, e.g. intake cooling or oil cooling.

Radiator fan malfunctions

A malfunctioning radiator fan is noticed when it does not automatically switch on as the engine temperature rises. The temperature check light on the dashboard lighting up while the fan stands still, indicates a defective unit. This rarely occurs with radiator fans. For electric fans, on the other hand, this is a rather common malfunction. Yet, a defect is not always caused by the fan or its motor. Before you start disassembling a non-functional fan, be sure to check all accessory components first. The fan is located in the proximity of the radiator and therefore, the engine's plug-in contacts, switch and sensor could be corroded. In this case, scratching corrosion from the contacts should do the trick. Connecting the fan to the battery with two cables should make it work. Now the fan motor can be excluded as a cause. The advantage is, that sensor and switch are considerably easier to replace than the large fan. Bypassing the fan is also an adequate method when a system malfunction occurs way ahead of the next repair occasion. It is better to drive with a fan permanently running, enabling you to safely reach the nearest garage without risking any engine overheating. If it turns out to be a fan motor malfunction, the entire unit is replaced. Retailers now offer a a complete set with fan , motor, cables, frame, screws and blades. The motor is fully integrated in most electric fans and cannot be replaced separately.

Radiator fan repair

The radiator fan is screwed directly onto the radiator with 4 – 6 bolts. For a simple disassembly, remove the radiator for a better access to the bolts. Prior to removing the radiator fan, please check the repair manual. Principally, switch, sensor and its relay are replaced along with the radiator fan. This renewal of all ventilation components enable a confident start into the next summer.