Fan clutch for your car

The engine fan of a car is situated right next to the radiator. It task is providing the radiator with an extra air flow when it can no longer reach its engine cooling performance. This happens when the engine is overheating due to excess strain (e.g. a long uphill drive), hot weather, stationary running or a defect in the cooling system. In the course of car history, several attempts have been made at airing the radiator by a blower. Fan propeller control and regulation The fan propeller generates an air flow by its rotation, streaming through the radiator, removing the lingering hot air. The cooling water's waste heat is in its turn released into the air. This process prevents overheating to a certain extent before the engine sustains excessive damage by piston seizure, piston jamming or a burned cylinder head gasket. In early cars the prop fan was permanently driven with help of spur gear, vertical shafts or a belt drive. The permanent airing of the radiator was not ideal for the operation of the car. It caused a bad engine performance and an inaccurate cooling of the cooling water. This resulted in the necessity of providing the fan prop with a control for it to work only when necessary. Up until the early 1990ies, fans and the magnetic clutches were a popular technology for rotation speed control of the fan propeller. A magnetic clutch switches the fan on and off with a bi-metal spring connected to a magnet. This part switches the fan via a complex, closed system in which an expanding, liquid drives a blade wheel. Both fan clutch versions are now obsolete and no longer used in new cars. The up-to-date version of the fan is equipped with a motor, controlled by a thermal switch. Modern cars offer an exact airing of the cooling system with adjusted rotation speed of the fan prop. Replacing a defective fan clutch Clutches are only used in old cars, and therefore a defect of these clutches might occur more often. A defective fan clutch might be the cause of an overheating or even boiling engine. If the fan clutch is suspect, it can be tested: The simplest way is stationary running of the engine and waiting until the fan starts. Sufficiently warm weather conditions are necessary, as otherwise it might last a while before the engine is has reached the required temperature. Under no circumstances the engine should be running in a closed space to prevent lethal carbon monoxide poisoning. A defective part can be detected by insufficient performance or leaking oil. A defective magnetic fan clutch often fails completely. In both cases the malfunctioning fan clutch can make itself heard by a creaking noise. Its replacement shouldn't be too difficult. The component is fixed to the radiator and connected to the engine with a drive belt. It can be directly unscrewed from the radiator or replaced simultaneously with the radiator. The bolt mounting the clutch to the radiator is extremely tight. Plenty of force or the right lever is needed to unscrew it. Purchase of a fan clutch Traditional fan clutches are only used in older cars, built until 2005. Therefore its demand is slowly dying out. Nevertheless, depending on construction and car, they are rather expensive. Prices for branded quality lie between 80 – 200 euro (£70 – 175). These parts are very important and therefore false economy is not a good idea: a failing fan can very soon lead to serious engine damage.