Car freewheel clutch alternator

How to detect the alternator freewheel clutch failure

It is easy to check the part serviceability on your own. For this, you have to remove the drive belt from it, smoothly rotate the freewheel clutch by hand, and then sharply stop it. If you feel that the alternator rotor continues spinning for some time after the pulley has stopped, the component is in good order, if not - replace it.

Then make sure that the part locking mechanism is in good condition. You need to lock the rotor with a screwdriver, and then try to rotate the freewheel clutch in both directions. If the part rotates freely in both directions, then it has failed.

You may identify that the alternator freewheel clutch needs diagnosis by the following signs:

• rattling or vibration in the passenger compartment, especially noticeable when driving at low speeds;
• clicks, whistles, noise in the engine compartment;
• premature wear or breakage of the belt;
• the battery charge indicator light flickers while the engine is running;
• dim light of headlights;
• rattling during engine start or stop;
• oil on the housing cover surface or on the freewheel clutch seal.

Causes of the alternator freewheel clutch failure

The alternator freewheel clutch has a limited service life which is 100,000 km on the average. But in many cases, the part may fail prematurely. Typically this is caused by the part operation without the protective cover or with a damaged seal. Ingress of dirt and moisture inside the part increase the risk of the freewheel clutch metal components corrosion, and the lubricant leakage will lead to accelerated abrasive wear, overheating and destruction of the bearing.

The alternator drive mounting errors can be the reason for the increased freeplay in the bearing. Excessively tensioned belt, misalignment of pulleys, rollers and tensioners considerably increase the load on the freewheel clutch, causing its failure. Often, similar effects result from the installation of non-original drive components the design of which does not comply with the standard ones.

Sometimes the alternator freewheel clutch premature failure occurs due to its poor quality, when the bearing design uses considerably fewer rollers than required, for example, 4 instead of 12. As a consequence, they wear out faster.

Replacing the alternator freewheel clutch

If you replace the part on your own, a set of special tools is required. On some vehicles, to open access to the freewheel clutch area you have to dismantle the fuel filter and the alternator. This is a rather time consuming procedure, which is best left to professionals. If you replace it on your own, use the following procedure:

1. Disconnect the negative terminal from the battery.
2. Lift and move aside the air duct, after dismantling the corresponding hoses, fasteners and connectors.
3. Dismantle the fuel filter.
4. Loosen and dismantle the belt from the pulley, pressing the tensioner lock pin with a wrench.
5. Unscrew the alternator mounting bolts, and then remove the bracket with the hinge.
6. Dismantle the alternator from the bracket, rotate it around its axis.
7. Unscrew the nut securing the wiring, and disconnect the connector.
8. Remove the alternator.
9. Remove the freewheel clutch using the drive socket, the retaining handle and the torque wrench.
10. Install a new part and tighten it with a torque of 80 ± 10 Nm.
11. Be sure to install a plastic protective cover, as the assembly operation is prohibited without it.