Datsun 620 Series 1977 Service Manual page 257

Manual Transmission
I
TROUBLE
DIAGNOSES
AND
CORREGTIONS
Condition
Difficult to intel11lesh
gears
Causes Jor difficu
t gear
shifting
are
classi
fied
to
troubles
concerning
control system
and transniissioo When
gear
shift lever
is
heavy
and it is
difficult
to
shift gears clutch
disengagement
may
also be unsmooth
First
make
sure
that clutch
operates correctly
and
inspect transmissi o
Gear
slips
out
of
mesh
In most
cases
this trouble
occurs
when
interlock b all check ball
and
or
spring
is
worn
or
weakened
or
when control
system
is
faulty
In
this
case
the
trouble
cannot
be
corrected by
replacing
gears
and therefore
trouble
shooting
must be carried
out care
fully
It
should also
be
noted that
gear
slips
out of mesh
due to vibration generated
by
weakened
fron
t
and
rear
engine mounts
Noise
When noise
occurs
with
engine idling and
ceases
when
clutch
is disengaged
or
when
noise
occurs
while
shifting gears
it
is
an
indicati90
that th
e
noise is
from
transmis
sion
t
Transmission
may
fa
ule
during engine
idling
Check air fuel mixture
and
ignition
timing
After
above
procedure
readjust engine
idling
Probable
cause
Worn
gear
shaft and
or
bearing
Insufficient
operating
stroke due
to
worn or
loose
sliding
part
Faulty
or
damaged synchronizer
Worn
interlock ball
Worn
check
ball
and
or
weakened
or
broken
spring
Wom
fork rod ball
groove
Wom
or
damaged bearing
Worn
or
damaged
gear
Insufficient
or
improper
lubricant
Oil
leaking
due to
faulty
oil seal
or
sealant
clogged
breather
etc
Worn
bearing
High
humming
occurs
at
a
high
speed
Damaged
bearing
Cyclic knocking sound
occurs also
at
a
19W
speed
Worn
spline
Worn
bushing
j
MT
23
Corrective
action
Replace
pair
or
replace
Replace
Replace
Replace
Replace
Replace
Replace
Add
oil
or
replace
with
designated
oil
Clean
Of
replace
Replace
Replace
Replace
Replace