Cooling fan clutch
1 – contact brush, 2 – contact ring, 3 – drive belt, 4 – coil, 5 – fan blades, 6 – fan blade mounting bolt and nut, 7 – central nut, 8 – axle, 9 – bearing, 10 – adjusting bolt, 11 – air gap, 12 – ground, 13 – bearings, 14 – timing mechanism drive cover
The cooling fan drive consists of two important parts - an electromagnetic clutch and a friction clutch. The electromagnetic clutch is driven by a V-belt and rotates on an axis that rests on two ball bearings mounted in the lug of the timing cover. At the front end of this axis is a ball bearing on which the friction clutch with the 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 supplies voltage to the carbon contact brush and, through the contact ring, to the electromagnetic coil. Under the action of the 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 coolant temperature decreases, the electromagnet is switched off, the gap is restored and the fan blades slow down, rotating only under the influence of the air flow and inertia.
For the clutch to operate properly, the drive belt tension must be normal, the electric sensor must be in good condition, the carbon brush must not be worn out, and the contact ring must be clean. The gap between the fan and the clutch bushing must be 0.5 mm on a cold engine. Before checking the gap, the fan blades must be removed by unscrewing the fastening nuts. Measurements are taken with a feeler gauge at several points around the circumference. To make adjustments, loosen the locknuts of the adjusting bolts and, by rotating them, set the required gap.
Removal and installation the fan clutch
1. Drain the coolant from the system.
2. Disconnect the pipes from the radiator and remove the radiator.
3. Remove the fan drive belt.
4. Fix the pulley and unscrew the central nut of the fan axle.
5. Rear engine mount.
6. Remove the electromagnetic clutch by lightly hitting the pulley and clutch with a mallet.
7. Remove the timing cover, remove the retaining spring ring and remove the fan shaft with bearings.
8. The coupling is installed in the reverse order of removal.