The alternator is not serviceable except for the extremely infrequent need to replace the graphite brushes. More serious damage cannot be repaired by amateur means.
To remove the cover (2) Bosch alternator, loosen the three Phillips head screws (1), remove the B+ wire from the stud (3) and remove the mounting tabs from the grooves (arrows).
Voltage regulator (2) held on by two Phillips head screws (1). Numeric «3» the axis of the sliding contact in the generator is indicated.
On the dismantled voltage regulator (4) we marked the length of the contact brushes (2) arrows. Numeric «1» shows the contacts of the voltage regulator, «3» - fixing screws.
Charging voltage test
1. Connect a voltmeter between the positive pole of the generator and ground.
2. Run the engine at medium speed.
3. With a working voltage regulator, the device will show approximately 13.3 to 14.6 V.
4. If not, check graphite brushes or replace regulator.
5. Otherwise, the generator itself is faulty.
Checking graphite brushes
1. Disconnect the negative pole of the battery.
2. Depending on the vehicle model, provide access to the back of the generator (e.g. remove expansion tank or engine compartment lining) or dismantle the generator.
3. Remove the cover on the back of the generator.
4. Remove the regulator from the generator. To do this, loosen both fixing screws.
5. Slightly tilt the adjuster so that the graphite brushes do not hang down.
6. Measure the protrusion of the graphite brushes: new graphite brushes are about 13mm long; wear value 5 mm.
Replacement of graphite brushes
Replacement of graphite brushes in modern generators is no longer provided - graphite brushes are no longer supplied as spare parts. If they are worn out, then you need to completely change the regulator.
But if someone can get graphite brushes in a workshop for repairing electrical equipment of cars as spare parts, he can make a separate replacement: in this case, you need a soldering iron, solder, and, in addition, the ability to solder. The description below refers to a Bosch generator:
1. Remove the regulator from the generator as described above.
2. Unsolder the connecting harnesses, remove the graphite brushes.
3. Remove pressure springs from old brushes and put on new brushes.
4. Solder the connecting harnesses.
5. Use a little tin solder when doing this and work quickly so that the connecting harnesses do not become saturated with tin. Otherwise, they will lose their flexibility.
Tip: With the regulator removed, you can also check the copper slip rings of the alternator core (graphite brushes move on them). If they already have deep traces of running-in, then they can be bored and polished in a car electrical equipment repair shop.
Dismantling the generator
1. Disconnect the battery wire connected to ground, otherwise there is a danger of a short circuit.
2. Four-cylinder engine: where present, unscrew the ground wire.
3. Remove V-ribbed belt (described in the chapter below).
4. Remove the connected wire.
5. Unscrew the mounting bolts of the generator clamp and remove them, while holding the generator.
6. Six-cylinder engine: remove the ribbed belt (described in the chapter below).
7. Remove the bottom cover of the engine compartment.
8. Remove the connected wire and fresh air guide from below.
9. Loosen the mounting bolts, remove the generator.
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