Maintenance Tips of Overrunning Alternator Clutch Pulley Testing and Diagnosis
The overrunning alternator pulley (also called the alternator freewheel clutch pulley) must be checked periodically to ensure proper operation of the unit drive and to prevent damage.
The alternator freewheel clutch pulley can be tested as follows:
Step 1: Dynamic Test with Engine Running
- Open your bonnet;
- Start the engine and allow it to idle;
- Observe the belt drive;
- Operate the engine at different speed ranges and perform a visual inspection;
- Turn off the engine and observe the alternator freewheel pulley;
Clutch pulley failure can be identified by the drive not operating properly and the noise that accompanies it. The alternator with a good clutch pulley should slow down and stop when the engine is shut off.
Step2: Static Test with Engine Off
- Turn off the engine;
- Remove the ignition key;
- Remove the V-belt;
- Remove the dust-free cap from the alternator pulley;
- Use a wrench tool;
- Grasp and hold the outer ring of the pulley with one hand;
- Use the other hand to turn the wrench tool in both directions;
If the freewheel clutch pulley is operating properly, the shaft will rotate freely in one direction and be locked in the other direction. Depending on the manufacturer, the resistance in the locked direction may be increased.
If the above results are not achieved, the OAP alternator pulley must be replaced.
Repair instructions !!
Whenever any repair work is carried out on the drive, the overrunning alternator pulley must be tested.
We recommend the following steps:
If a new alternator is installed, always replace the freewheel clutch pulley at the same time.
Replace V-belt, clamping device and overrunning alternator pulley at the same time.
Replace the alternator flywheel clutch after 100,000-120,000 kilometers at the latest.
Observe the repair and maintenance instructions of the relevant vehicle manufacturer.