21942641 Volvo.Penta Camshaft

Illustration 1 g03792595
(3) Rear coverRemove the rear cover (3) to access the diodes in the generator.Diode Removal
Use the following procedure to replace the diodes.
Illustration 2 g03792622
(4) Diode crescent assembly (5) Mounting nuts that attach the leads from the rotor to the diode crescent plates (6) Leads from the rotor that are to be disconnected (7) Mounting bolts for the diode assembly (diode wheel)Note: The diode assembly includes the varistor assembly, the diodes, diode crescent plates, and the mounting plate (diode wheel) that the diode crescents are mounted to.
Remove the mounting nuts (5) that attach the leads (6) from the main rotor to the diode assembly (4) .Note: Make sure that the diode leads (6) and assemblies (4) are appropriately labeled to ensure correct installation when installation occurs.
Remove the leads (6) .
The leads to each diode will need to be unsoldered and removed from the diodes.
Illustration 3 g03779481
Diode assembly (diode wheel) removed
Remove the bolts (7) that secure the diodes assembly (4). Remove the diodes assembly.
Illustration 4 g03792647
(9) Varistor assembly (10) Varistor assembly mounting nuts
Remove the mounting nuts (10) for the varistor assembly (9). Remove the varistor assembly. Refer to Illustration 4.
Illustration 5 g03792662
(5) Mounting nuts (10) Mounting nuts
Remove the mounting nuts (5) and (10) for the diode crescent. Remove the diode crescent assembly (4). Refer to Illustration 5.
Properly secure the diode crescent in a bench vice that provides protection on the jaws so no damage will occur to the diode crescent.
Carefully remove all of the diodes from the diode crescent.Diode Installation
Install three new diodes, of the same polarity, in the diode crescent from which the diodes were removed.Note: When one diode fails, the other two diodes are forced to operate in overload condition. The overload condition for the remaining, good diodes reduces the expected life time of the diodes. Due to the possible risk of damage to the good diodes from an overload condition, Caterpillar recommends that all of the diodes be replaced.
Install three new diodes in the other diode crescent, of the opposite polarity from what was installed in Step 1.
Illustration 6 g03794995
Typical torque wrench attachment for installing diodes
Secure all diodes by tightening the diodes with a torque wrench. The correct torque values are listed in Table 1.
Table 1
Diode base thread (mm)     Torque wrench attachment dimension "X" mm (3)     Diode torque (N-m)    
M6     11    
2 N m (1.5 lb ft)    
M8     17    
4 N m (3 lb ft)    
M12     24    
10 N m (7 lb ft)    
M16     32    
30 N m (22 lb ft)    
( 3 ) Refer to Illustration 6.
Illustration 7 g03828015
(4) Diode crescent assembly (5) Mounting nuts that attach the leads from the rotor to the diode crescent assembly (6) Leads from the rotor that are to be disconnected (7) Mounting bolts for the diode assembly (diode wheel) (10) Mounting nuts that attach the varistor assembly and diode crescent to the diode assembly (diode wheel)
Install each of the diode crescent assemblies (4) and diode wheel, removed during the disassembly procedure. Torque the mounting nuts (5) and (10) to 11 N m (8 lb ft). Torque the mounting bolts (7) to 11 N m (8 lb ft).
Connect all of the leads from the exciter rotor to the appropriate diode.Note: The leads to the diodes must be soldered at the diode connection point with a 130 W soldering iron.Note: Care must be taken to not over heat the diodes and thus damage the diode or other components while soldering.