Komatsu 75001, Shop Manual

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SEN03850-00
WA250, 250PZ-6 40-600
23
600 Troubleshooting of engine (S-mode)
S-16 Vibration is excessive
S-16 Vibration is excessive
1
General causes why vibration is excessive
q
Defective parts (abnormal wear, breakage)
q
Misalignment between engine and chassis
q
Abnormal combustion
a If abnormal noise is made and vibration is excessive, carry out trou-
bleshooting for “S-15 Abnormal noise is made“, too.
Causes
S
tu
ck dy
na
mi
c val
v
e
sys
te
m (
v
a
lv
e
, r
o
ck
er
l
e
ve
r)
W
o
rn
mai
n
b
ea
rin
g,
con
ne
c
ting r
o
d be
ar
ing
Im
p
rop
er
ge
ar
t
rai
n ba
ck
la
s
h
Wo
rn
c
a
m
s
h
a
ft b
u
s
h
in
g
Im
p
rop
er
f
ue
l inj
ec
ti
on
t
imi
ng
(
a
bn
or
m
a
lit
y in
c
oo
lan
t t
em
p
er
a
tu
re
s
en
so
r,
bo
os
t t
em
p
er
a
tur
e s
e
ns
or
)
Lo
os
e en
gi
ne
mou
n
ting
b
o
lts,
br
o
k
e
n
cu
shi
o
ns
Mi
sa
lign
me
nt
b
e
tw
e
e
n
e
n
g
in
e
an
d d
e
vi
ce
s on
ap
pl
ic
ab
le
m
a
ch
ine s
id
e
B
ro
k
en
ou
tp
ut
sh
af
t,
pa
rt
s
i
n
da
mp
er
on
a
p
p
lic
a
b
le
m
a
ch
in
e
si
de
Qu
e
s
tio
n
s
Confirm recent repair history
Degree of use of machine Operated for long period E E E
Condition of vibration
Suddenly increased Q Q
Gradually increased
Q Q Q
Non-specified oil is being used Q Q
Metal particles are found when oil filter is drained w w
Metal particles are found when oil pan is drained w w
C
h
eck
it
em
s Oil pressure is low at low idle
Q Q
Vibration occurs at mid-range speed Q Q
Vibration follows engine speed Q Q Q Q
Exhaust smoke is black w Q
T
rou
bl
es
ho
ot
ing
Inspect dynamic valve system directly q
Inspect main bearing and connecting rod bearing directly q
Inspect gear train directly q
Inspect camshaft bushing directly
q
Confirm with monitoring function q
Inspect engine mounting bolts and cushions directly q
When alignment is checked, radial runout or facial runout is detected q
Inspect output shaft or inside of damper directly
q
Remedy
R
e
pl
ac
e
R
e
pl
ac
e
R
e
pl
ac
e
R
e
pl
ac
e
R
e
pl
ac
e
R
e
pl
ac
e
Ad
ju
s
t
R
e
pl
ac
e