Isuzu AA-6HK1T, Workshop Manual

Page: 203 / 242

6D3–8 STARTING AND CHARGING
3. Check the diode trio for continuity in both directions.
If there is continuity and/or an open circuit in both
directions, the rectifier must be replaced.
Legend
(1) Positive diode
(2) Diode terminals
(3) A part of negative diode
Front bracket
Turn the bracket. Listen for bearing noise (a scraping
sound). Feel for rough rotation. Replace the bracket if
either of these conditions is present.
Check for grease leakage. If leakage is minimal, wipe it
away. If leakage is excessive, replace the bracket.
Regulator
The regulator cannot be checked in the absence of the
other components. Check regulator operation after
alternator reassembly.
Reassembly
Follow the disassembly steps in the reverse order.
Note the following precautions.
•
No lubrication is required. Bearings are
prelubricated.
•
Wipe away any grease leakage from the bearing
area.
•
Use high-temperature solder (melting point of
230°C).
•
Use a 180 – 280 watt soldering iron to solder the
leads as quickly as possible. Do not apply the
soldering iron for more than 5 seconds. Diode
damage will result.
•
Bracket, rotor, and stator reassembly is difficult
because of the tight fit of the components. To make
reassembly easier, heat the area around the rear
bracket bearing box to approximately 55°C.
Tightening torques
Pulley fixing nut: 147 N·m (15 kgm/108 lbft)
Through bolts: 5.1 N·m (0.52 kgm/3.8 lbft)
Bearing retainer screws: 3.6 N·m (0.37 kgm/
2.7 lbft)
Coil retaining screws: 3.6 N·m (0.37 kgm/2.7 lbft)
Rectifier retaining screws: 3.6 N·m (0.37 kgm/
2.7 lbft)
Regulator retaining screws: 3.4 N·m (0.35 kgm/
2.5 lbft)
Nuts for stud bolts: 8.8 N·m (0.9 kgm/6.5 lbft)
Bench testing
Perform bench tests on the reassembled alternator.
Voltage regulation
1. Make connections as shown in the illustration on the
following page. Use an ammeter with a scale of 0 –
100 amperes and voltmeter with a scale of 0 – 30
volts.
2. Close switch 1 and open switch 2. The lamp should
light.
If the lamp does not light, check the voltage at
terminal-L.
If the voltage is nearly equal to battery voltage (24V),
check the alternator.
If the voltage is low, check for an open lamp and
related circuitry.
3. Slowly increase alternator speed.
The lamp should turn off as alternator speed
approaches 1,300 min
-1
.
4. Check the voltage as alternator speed increases.
If the voltage fluctuates wildly during alternator
speed increase and rises above 30 volts, the IC
regulator is probably defective.
If the voltage does not exceed battery voltage (24V),
the alternator is defective (no generation of
electricity). Check alternator components again.
5. Increase alternator speed to approximately 500 min
-1
.
6. Note the ammeter reading.
If the reading is 5 amperes or less, note the voltmeter
reading (be sure that alternator speed remains
constant). This is the regulated voltage.
If the reading is more than 5 amperes, continue to
operate the ammeter at 500 min
-1
until the reading
falls to 5 amperes or less.
If the reading does not fall, replace the battery.
If the reading still does not fall, the alternator is
defective and must be repaired or replaced.
1
3
2
060EY00006