MAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
474
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
——Clean the bearings, and check them for any
looseness. Replace them if any.
——Check if the weld of the field coil with the slip
ring is reliable (the field coil resistance is 5~6
Ω).Check if the weld of the stator lead wires with the
diode is reliable.
Fig. 11-3-4 Checking the generator diode
Fig. 11-3-5 Checking the generator diode
——Check the diodes, remove the connecting wires
of the stator winding with diodes, and then check
one diode after another with a multimeter
（
resistance×1 scale
）
. See Fig. 11-3-4.
Check the diodes on the rear cover according to the
following methods. Rest the multimeter negative
testbar on the rear cover and the positive testbar on
the out terminal of the diode, and the value shown
on the electric meter should be no more than 10Ω.If
the ohm value shown is low, it indicates the diode
has been broken down; if the ohm value is high, it
indicates the diode circuit has been broken and the
diodes should be replaced. Then rest the negative
testbar on the out terminal of the diode, and the
positive testbar on the rear cover. The value shown
on the ammeter should be above 10000Ω.If the ohm
value is very low, it means the diode has been
damaged.
As the 3 diodes inserted on another element board
conduct electricity in the reverse direction, the
measured result should be the opposite. The
method is shown in Fig. 11-3-5.
Caution:
It is definitely forbidden to check the
insulation of the diodes or generator with a
tramegger (megger) or 220 V AC.
(3) Reinstalling the generator after repair: combine
the rotor with the drive end cover and stator cover,
and then connect the diodes with the stator winding.
Then install the rotor, drive end cover and the rear
cover. Fit 3 bolts and tighten them according to
required torque. After that, the reinstallation is
finished.
(4) Set the generator in no-load and generating
tests, and the performance should comply with
related requirements.
1.3 Maintenance of the Generator belt
The generator belt is used to transmit the crankshaft
torque which is output by the damping pulley to the
generator assembly, power steering pump and
refrigerating compressor assembly, and thus makes
them work normally.
Above 10000Ω
Above 10000Ω
