2001 BMW 525i brake fluid reservoir

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7 Maintenance
< Unbolt caliper from steering arm to properly inspect:
Brake pad thickness
(A)
Brake rotor
Condition of caliper seal
(B)
Condition of caliper slider bolts (C)
NOTE-
Brake caliper removal and installation procedures are given
in
340 Brakes.
Brake pad lining minimum thickness
Dimension
A 3.0 mm (0.12 in)
Brake system, inspecting
Routine maintenance of the brake system includes maintain-
ing the brake fluid in the reservoir,
checking bralte pads for
wear, checking parking brake function, and inspecting the
system for fluid lealts or other damage:
- Check that bralte hoses are correctly routed to avoid chafing
or
Itinking.
- lnspect unions and brake calipers for signs of fluid leaks.
- lnspect rigid lines for corrosion, dents, or other damage.
- Inspect flexible hoses for cracking
- Replace faulty hoses or lines as described in 340 Brakes.
WARNING-
Incorrect installation or overtightening hoses, lines, and
unions may cause chafing
orlealage. This can lead to partial
Parking brake, checking
The parking brake system is independent of the main braking
system and may require periodic adjustment depending on
use. Adjust the parking brake if the brake lever can be pulled
up more than
8 clicks. Check that the cable moves freely. A
description of the parking brake and
parlting bralte adjust-
ment can be found in
340 Brakes.

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020-26
Maintenance
NOTE-
The parking brake may lose some of its effectiveness if it is
not used frequently This is due to corrosion build-up on the
parking brake drum. To remove corrosion, apply the parking
brake just until it begins to grip, then pull the lever up one
more stop (click). Drive the car approximately 400 meters
(1,300
ft.) and release the brake. To recheck the adjustment
of the parking brake see
340 Brakes.
Clutch fluid, checking
In cars equipped with manual transmission and clutch, the hy-
draulic clutch and the brake system share the same reservoir
and the same bralte fluid. Clutch fluid level and brake fluid lev-
el are checked at the same time.
NOTE-
* See 340 Brakes for more information.
See
210 Clutch for information on the clutch and the
hydraulic clutch operating system.
Differential oil level, checking
The E39 differential is filled with lifetime oil that ordinarily
does not need to be changed.
BMW recommends using only
a specially formulated synthetic gear oil
(SAF-XO) that is
available through an authorized
BM\N dealer parts depart-
ment. For additional information on this lubricant and any
other lubricants that may be compatible, contact an
authorized
BMW dealer service department.
< Check rear differential oil level at filler plug (arrow).
- Check lubricant level with car on a level surface:
Level is correct when fluid just reaches edge of filler hole.
If necessary, top up fluid.
Replace filler plug sealing ring.
Install and tighten oil filler plug when oil level is correct.
NOTE-
Use either a 14 mm or 17 mm Allen socket to remove the
drain plug.
If the car is raised in the air, it should be level when
checking or filling final drive fluid level.
Tightening torque
Filler plug to final drive housing 70 Nrn (52 it-lb)

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Tool for bleeding clutch hydraulics (Tool No. 21 5 030)
21 5 030 I
The clutch is hydraulically actuated by the master and slave
cylinders. With the self-adjusting clutch
(SAC), clutch disc
wear is automatically taken up through the self-adjusting
pressure plate springs, making pedal feel consistent through-
out the life of the clutch.
A soft or spongy feel to the clutch pedal, long pedal free-play,
or grinding noises
from the gears while shifting can all indi-
cate problems with the clutch hydraulics. In these circum-
stances it is best to
star? with a clutch fluid flush, followed, if
necessary, by replacement of the hydraulic parts.
NOTE-
The clutch hydraulic system shares the fluid reservoir and flu-
id with the brake hydraulic system.
Clutch hydraulic system,
bleeding and flushing
If the clutchlbralte fluid is murky or muddy, or has not been
changed within the last two years, flush the system and
change the fluid. Flushing the old fluid from the clutch lines is
done using a bralte system pressure bleeder.
- Remove brake fluid reservoir cap. Using a clean syringe, re-
move brake fluid from reservoir. Refill reservoir with clean
DOT
4 bralte fluid.
Worlting inside engine compartment, remove left
interiorven-
tilation filter housing:
Release 3 plastic taps
(A) on duct. Earlier models use a
single release latch.
Rotate duct inward to remove.
Disconnect electrical harness to hood position switch.
Remove filter housing cover.
Release spring lock
(B) on interior ventilation housing and
remove housing.

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Anach pressure brake bleeder to fluid reservoir and pump
bleeder a few times to pressurize hydraulic fluid system.
CAUTION-
* Do not exceed 2 bar (29 psi) pressure at the fluid resenfoil
when bleeding or flushing the hydraulic system.
Brake fluid is poisonous, highly corrosive and danger-
ous to the environment. Wear safety glasses and
rub-
bergloves when working with brake fluid. Do not siphon
brale fluid with your mouth. Immediately clean away
any fluid spilled on painted surfaces and wash with wa-
ter, as brale fluid will remove paint.
Always use new brake fluid from a fresh, unopened
container.
Brake fluid will absorb moisture from the air.
This can lead to corrosion problems in the clutch and
brake hydraulic systems, ;nd will also lower the brake
fluid boiling point. Dispose of brale fluid properly.
- Raise and safely support vehicle.
WARNING-
Make sure the car is stable and well supported at all times.
Use a professional automotive lift orjackstands designed for
the purpose. A floor
iack is not adequate support.
- If necessary, remove transmission splash shield.
Hydraulic system, bleeding
Worlting underneath transmission, connect a hose from
clutch slave cylinder bleeder valve
(arrow) to a container.
Open bleeder valve and allow bralte fluid to expel until
clean fluid comes out, free of air bubbles.
Close bleeder valve and disconnect pressure bleeding
equipment from fluid reservoir.
Slowly operate clutch pedal about
10 times. Fill reservoir
with clean fluid as necessary.
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21 0-6
1 Clutch
Hydraulic system, bleeding
(using
BMW special tool 21 5 030)
4 Working underneath transmission, remove slave cylinder
mounting nuts (arrow) from clutch housing and remove
cylinder. Leave fluid line attached.
4 Use BMW special tool 21 5 030 to press slave cylinder push-
rod completely into slave cylinder.
Hold slave cylinder so that bleeder valve is at highest point.
Open bleeder valve and allow brake fluid to expel until
clean fluid comes out, free of air bubbles.
* Close bleeder valve and disconnect pressure bleeding
equipment from fluid reservoir.
Slowly unscrew and detach special tool 21
5 030 from
slave cylinder.
CAUTION-
Do not remove tool if hydraulic system is pressurized.
- Reinstall slave cylinder.
Tightening torque Slave cylinder to transmission case
22 Nm (1 6 ft-lb)
- Slowly operate clutch pedal about 10 times. Fill reservoir with
clean fluid as necessary.
Clutch master cylinder, replacing
The clutch master cylinder is mounted to the pedal assembly
directly above the clutch pedal.
Working inside engine compartment, remove left interior
ventilation filter housing:
Release 3 plastic taps
(A) on duct. Earlier models use a
single release latch.
Rotate duct inward to remove
Disconnect electrical harness to hood position switch.
Remove filter housing cover.
Release spring
loclc (B) on interior ventilation housing and
remove housing.

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21 0-7
Clutch
- Remove brake fluid reservoir cap. Using a clean syringe.
remove brake fluid from reservoir to below level of clutch
hydraulic supply hose.
- Detach clutch hydraulic supply hose from brake fluid reser-
voir. Plug reservoir outlet and hose.
4 Remove lower dash trim panel fasteners (A) and (B).
Lower trim panel and disconnect wiring harnesses on back
side of panel.
Remove trim panel.
4 Working under dash, remove clutch master cylinder pushrod
retaining clip (arrow) and pin from clutch pedal.
4 Remove master cylinder mounting bolts (arrows)

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21 0-8
Clutch
4 Remove hydraulic line locking clip (1) and pull line (2) off
master cylinder.
CAUTION-
. To prevent brake fluidspill, wrap clutch master cylinder with
shop rags when removing hydraulic fluid lines from master
cylinder.
* Brake fluid damages paint andstains carpets. Clean off
any brake fluid on or
in the car immediately.
- Remove master cylinder with supply hose
4 Remove switch module from master cylinder.
Press locking button
(A) to release harness connector.
Pull harness connector
(8) off switch module.
Use screwdriver to lever
off switch module (C).
- Installation is reverse of removal.
CA UTlON-
Switch module must snap firmly into place on the master cyl-
inder during installation.
Tightening torques
Clutch master cylinder to pedal cluster
10 Nm (89 in-lb)
Fluid line
to master cylinder or slave cylinder 17 Nm (13 ft-lb)
- Fill fluid reservoir with clean fluid. Bleed clutch hydraulics as
described earlier.
Clutch slave cylinder, replacing
4 Working inside engine compartment, remove left interiorven-
tilation filter housing:
Release
3 plastic taps (A) on duct. Early models: release
latch.
Rotate duct inward to remove.
Disconnect electrical harness to hood position switch.
Release spring lock (B) on interior ventilation housing and
remove housing.
- Pinch off brake fluid supply hose to clutch master cylinder us-
ing BMW special tool
13 3 01 0 or equivalent hose clamping
tool.

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300-1 2
I Sus~ension, Steerincl and Brakes - General
E39 electronic brake and stability control
systems application table
(528i, 54bi) Traction (ASC) I Hydraulic unit in right rear of engine compartment 1
Identifiers
Year (model)
I No precharge pump 1
Manuf. up to 911998 l~utomatic Stability Control plus I Electronic control module next to glove compartment
System
Precharge pump in
lefl front of engine compartment, below
steering fluid reservoir
Separate rotational rate (yaw) and lateral acceleration sensors
I I
Combined rotational rate (yaw) and lateral acceleration sensors
Electronic control
module next to glove compartment
Hydraulic unit in right rear of engine compartment
Manuf. up to 911999
(540i optional)
I I
ABS system
Dynamic Stability Control (Bosch
DSC
Ill v. 5.3)
The electronically controlled
ABS maintains vehicle stability
and control during emergency braking by preventing wheel
lock-up.
ABS provides optimum deceleration and stability dur-
ing adverse conditions. It automatically adjusts brake system
hydraulic pressure at each wheel to prevent wheel lock-up.
Control
moduleihydraulic unit
in right rear of engine compartment
No precharge pump
Manuf. from
911999
(all models)
Automatic Stability Control (ASC)
Dynamic Stability Control (Boscli
DSC Ill v. 5.7)
NOJE-
ASC (Automatic Stability Control) may also be referred to as
ASCiT (Automatic Stability ControkTraction).
ASC works in conjunction with ABS and the engine manage-
ment system to enhance vehicle control. The main function of
the
ASC system is to maintain the contact between the tires
and the road surface under all driving conditions. This is
achieved through exact application and management of brak-
ing and drivetrain forces.
The
ASC system improves traction by electronically applying
the rear brakes when the rear drive wheels are spinning at a
faster rate than the front wheels. The combined
ABSIASC
control module, operating through the ABS hydraulic control
unit, modulates braking force at the rear wheels.
In addition,
ASC overrides the throttle opening to reduce en-
gine torque and maintain vehicle traction. Because the throt-
tle is controlled electronically, the driver cannot increase
engine power output during
ASC intervention regardless of
how far the accelerator pedal is pushed.