340-2
BRAKES
When
troubleshooting,
keep
in
mind
that
tire
inflation,
wear
and
temperature
can
affect
braking
and
suspension
.
See310
Front
Suspension
for
more
information
on
front
suspension
parts
inspection
.
Table
a
lists
symptoms
of
brake
problems,
their
probable
causes,
and
suggested
corrective
actions
.
Table
a
.
Brake
System
Troubleshooting
Symptom
1
Probable
cause
1
Repairs
Brake
squeal
a
.
Incorrectly
installed
brake
pads
or
a
.
Check
component
installation
.
parking
brake
shoes
b
.
Brakepad
carriers
dirty
or
corroded
b
.
Remove
brake
pads
and
clean
calipers
.
c
.
Brake
pad
anti-rattle
springs
faulty
or
c
.
Install/replace
anti-rattle
springs
.
missing
d
.
Brakepads
heat-glazed
or
oil-soaked
d
.
Replace
brake
pads
.
Clean
rotors
.
Replace
leaking
calipers
as
required
.
e
.
Wheel
bearings
worn
(noise
most
e
.
Replace
worn
bearings
.
See310
Front
Suspension
pronounced
when
turning)
or
330
Rear
Suspension
.
Pedal
goes
to
f
loor
when
braking
a
.
Brake
fluid
leve¡
low
due
to
system
a
.
Check
fluidlevel
and
inspect
hydraulic
system
for
leaks
signs
of
leakage
.
Fill
and
bleed
system
.
b
.
Master
cylinder
faulty
I
b
.
Replacemaster
cylinder
.
Low
pedal
after
system
bleeding
1
a
.
Master
cylinder
faulty
1
a
.
Replace
master
cylinder
.
Pedal
spongy
or
brakes
work
only
a
.
Air
in
brake
fluid
a
.
Bleedsystem
.
when
pedal
is
pumped
b
.
Master
cylinder
faulty
(interna¡
return
b
.
Replacemaster
cylinder
.
spring
weak)
c
.
Leaking
line
or
hose
unions
c
.
Repair
or
replace
lines
and
hoses
.
Bleed
system
.
Excessive
braking
effort
a
.
Brake
pads
wet
a
.
Use
light
pedal
pressure
to
dry
pads
while
driving
.
b
.
Brake
pads
heat-glazed
oroil-soaked
b
.
Replace
brake
pads
.
Clean
rotors
.
Replace
leaking
calipers
.
c
.
Vacuum
booster
or
vacuum
hose
con-
c
.
Inspect
vacuum
lines
.
Test
vacuum
booster
and
re
nections
to
booster
faulty
place
as
required
.
Test
vacuum
non-return
valve
for
one-way
air
flow
.
Brakes
pulsate,
chatter
or
grab
a
.
Warped
brake
rotors
a
.
Resurface
or
replace
rotors
.
b
.
Brake
padsworn
b
.
Replace
brake
pads
.
c
.
Brake
pads
heat-glazed
or
oil-soaked
c
.
Replace
brake
pads
.
Clean
rotors
.
Replace
leaking
calipers
.
Uneven
braking,
car
pulís
to
one
a
.
Incorrect
tire
pressures
or
worn
tires
a
.
Inspect
tire
condition
.
Check
and
correct
tire
pres-
side,
rear
brakes
lock
sures
.
b
.
Brake
pads
on
one
side
of
car
heat-
b
.
Replace
brake
pads
.
Clean
rotors
.
Replace
leaking
glazed
or
oil-soaked
calipers
.
c
.
Caliper
or
brake
pads
binding
c
.
Clean
and
recondition
brakes
.
d
.
Worn
suspension
components
d
.
Inspect
for
worn
or
damaged
suspension
compo-
nents
.
See
310
Front
Suspension
or
330
Rear
Sus-
pension
.
Brakes
drag,
bind
or
overheat
a
.
Brake
caliper
or
brake
pads
binding
a
.
Clean
or
replace
caliper
.(
b
.
Master
cylinder
faulty
b
.
Replacemaster
cylinder
.
WARNING
-
On
cars
with
All
Season
Traction
(AST),
special
BMW
service
equipment
is
required
to
properly
bleed
the
ABS/AST
system
.
For
safety
reasons,
the
brake
system
on
carswith
ABS/AST
must
not
be
bled
using
the
procedures
described
inthis
repair
group
.
BLEEDING
BRAKES
Brake
bleeding
is
usually
done
for
one
of
two
reasons
:
Ei-
ther
to
replace
oíd
brake
fluid
as
part
of
routine
maintenance
or
to
expel
trapped
air
in
the
system
that
resulted
from
open-
ingthe
brake
hydraulic
system
during
repairs
.
BLEEDING
BRAKES
Alwaysuse
new
brake
fluid
from
an
unopened
container
.It
is
important
to
bleed
the
entire
system
when
any
part
of
the
hydraulic
system
has
been
opened
.
On
cars
not
equipped
with
traction
control
(AST),
brake
system
bleeding
should
be
done
with
a
pressure
bleeder
.
On
cars
with
AST,
brake
bleed-
ing
should
be
done
by
an
authorized
BMW
dealer
.
WARNING
-
On
cars
with
All
Season
Traction
(AST),
special
BMW
service
equipment
is
requíred
to
properly
bleed
the
ABS/AST
system
.
For
safetyreasons,
the
brake
system
on
carswith
ABS/AST
must
not
be
bled
using
the
procedures
described
inthís
repair
group
.
