Cooling system fan

The cooling fan drive consists of two important parts - electromagnetic and friction clutches. The electromagnetic clutch is driven by a V-belt and rotates on an axle supported by two ball bearings mounted in the lug of the timing cover. A ball bearing is installed at the front end of this axle, on which a friction clutch with fan blades rotates freely. There is an air gap between the electromagnetic and friction clutches if the engine temperature does not exceed 71°C. When the coolant temperature rises above 85°C, a sensor mounted on the radiator energizes the carbon contact brush and, through the slip ring, the solenoid coil. Under the action of a magnetic field, the friction clutch is attracted to the electromagnetic one, and the fan blades begin to rotate at the speed of the pulley. When the temperature of the coolant decreases, the electromagnet is turned off, the gap is restored and the fan blades slow down, rotating only under the influence of air flow and inertia.

For normal operation of the clutch, the drive belt tension must be normal, the electrical sensor is in good condition, the carbon brush is not worn out, and the slip ring is clean.

The gap between the fan and the clutch sleeve is 0.5 mm on a cold engine. Before checking the gap, it is necessary to remove the fan blades by unscrewing the fastening nuts. Measurements are made with a probe at several points along the circumference. To carry out the adjustment, it is necessary to loosen the lock nuts of the adjusting bolts and, by rotating them, set the required clearance.