Alternator - overhaul

Electrical system / Alternator - overhaul

1 Overhaul of the alternator should be limited to renewal of the brushes. If the unit has covered a high mileage, it will be found more economical to exchange it for a new or factory-reconditioned one, rather than renew worn components on the original unit.

Brush renewal
(Marelli alternator)
2 Unscrew the nuts and take off the rear cover.

3 Unscrew the two small bolts and withdraw the brush holder (photos).

5.3A Alternator brush holder bolt

5.3B Removing alternator brush holder

4 Fit the new brush holder which is supplied complete with brushes, by reversing the removal operations.

Brush renewal
(Bosch alternator)
5 Where applicable, remove the radio suppression condenser (capacitor) from the rear end frame (one screw and washer, and a plug-in connection).

6 Undo the two screws which retain the brush holder to the rear frame of the alternator, then ease the holder out of the alternator. Inspect the brushes and if worn below the specified minimum length, they must be renewed.

7 Disconnect the brush leads by unsoldering or carefully cutting them.

8 When soldering the new brush leads, do not allow solder to run down them or their flexibility will be ruined.

9 When inspecting or renewing brushes, check the surface of the slip rings. Clean them with solvent or if they are very discoloured, use very fine glasspaper.

Fig. 9.1 Exploded view of typical alternator (Sec 5)

1 Pulley
2 Fan
3 Bolts
4 Washers
5 Drive-end bracket
6 Stator windings
7 Plate screw
8 Diode plate (rectifier pack) 9 Body
10 Brush
11 Spring
12 Brush holder
13 Condenser
14 Screws and washers
15 Screws and washers
16 Screws and washers
17 Plug socket
18 Suppressor
19 Shaft nut
20 Spring washer
21 Thrust ring
22 Bearing
23 Retainer plate
24 Thrust ring
25 Spring washer
26 Screw and washer
27 Key
28 Rotor
29 Bearing
30 Backing washer
31 Shield (where applicable)