Komatsu 75001, Shop Manual

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SEN03849-00
WA250, 250PZ-6 40-500
27
500 Troubleshooting of hydraulic and mechanical system (H-mode)
H-28 Fan revolution is abnormal (Fan sound/vibration is abnormally large or engine overheats)
H-28 Fan revolution is abnormal (Fan sound/vibration is abnormally
large or engine overheats)
1
Check the following with the operator.
q
Did the fan start making the abnormal sound sud-
denly?
o
Damage of the devices related to the fan and
fan motor
q
Did the engine overheat after the fan had started
making the abnormal sound?
o
Internal wear of the devices related to the fan
pump and fan motor, lowering of sealing per-
formance or dirt
Check for abnormality
q
Measure the fan speed to check for abnormality.
Check before troubleshooting
q
Check the level and type of the oil in the hydraulic
tank.
q
Check the hydraulic hoses, pump and motor for oil
leakage.
q
Check the fan for damage.
(Note): If “Lowering of engine performance” is judged, go to the
troubleshooting for the engine system (S mode).
Cause
Tank to
Pump
Charge
valve
Fan motor Others
a b c d e f g h i j k
Cl
oggi
ng or
suc
k
ed ai
r on pum
p suc
ti
on si
de
Def
ect
iv
e f
an
pum
p
M
a
lf
un
ct
ion of
r
e
lie
f val
v
e
Sei
z
ed br
ake ci
rc
ui
t sel
e
ct
or
sp
ool
Def
ect
iv
e f
an
m
ot
o
r
S
e
iz
e
d
O
N
/O
F
F
s
o
le
n
o
id
v
a
lv
e
M
al
fun
ct
ion of
EPC sol
eno
id va
lv
e
M
a
lf
un
ct
ion
of
s
u
ct
io
n s
a
fe
ty
val
v
e
Sei
z
ed f
or
w
ar
d-
rev
er
se
sel
ect
or
val
v
e
M
al
fun
ct
ion of
c
ont
rol
ler
Lower
ing of
engi
ne per
for
m
anc
e
No.
Remedy
Troubleshooting
C
E
X
E
X
E
X X
E
X
E
X
E
X
E
X X
Note
1 Fan speed is low (in fan 100% mode) Q
Q
Q Q
Q
Q
2 Fan hunts Q
Q Q
Q Q
3 Fan does not revolve
Q Q Q Q
4 Fan always revolves in reverse
Q Q Q
5 Fan does not revolve in reverse
Q Q Q