Maintenance Manual of 4M11 Series Diesel Engine For Land Power Generators
109
Observe the battery surfaces for cleanliness and
dryness and check whether the wiring terminals
and clamps are in good fit. Replace as soon as
possible in event of any damage.
Check the phase output voltage of alternator
(This voltage shall be approximately one half
of B+ output voltage.)
If there is high difference between phase terminal
(W/R/AC) output voltage and normal output and
the voltage drop is high when the alternator is
loaded, the alternator rectifier bridge or stator is
malfunctioned and the checking and replacement
shall be considered.
The malfunction symptom is not solved after
above checking.
Replace alternator regulator, rotor, or whole
alternator.
d) Unstable charging voltage
Malfunction 4: Unstable charging voltage
Vehicle symptom Fault Detection Solution
The voltmeter indicates the charging during
normal running of engine, but the pointer
fluctuates and the reading can’t be read (or the
charging indicator lamp turns off occasionally).
Loose belt or belt run-out for
alternator or related pulley
systems.
Tension belts for
alternator and related
pulley systems.
Looseness or poor contact at
connections of charging circuit
Check and tighten
connections of charging
circuit
Contamination of collector ring,
excessive wear of electric brush, or
softening or breakage of electric
brush spring
Disassemble
contaminants or replace
electric brush or electric
brush spring
Damage of regulator Replace the regulator.
e) Alternator noise
Malfunction 4: Unstable charging voltage
Vehicle symptom Fault Detection Solution
There is an abnormal
noise during running of
alternator.
The fixing bracket of alternator is
deformed or is too close to other
external housings.
Improve strength of fixing bracket and
adjust assembly status.
Looseness or slip of alternator belt Replace engine belt.
Loose alternator pulley Tighten pulley.
Oil shortage or damage of alternator
bearings
Replace alternator bearing
Low noise within alternator The stator coil is short circuited. Replace
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