1997 BMW 525i Brake lines

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330-1 9
Rear suspension1
Swing arm ball joint, replacing
- Raise rear end of car and remove wheel.
Make sure the car is firmly supported on jack stands de-
signed for the purpose. Place jack stands underneath struc-
tural chassis points. Do not place jack stands under
suspension
parts.
- Sport Wagon model: Support wheel bearing carrier from be-
low.
CA
UTION-
The shock absorberprevents the drive axle and wheel bear-
ing carrier from dropping too far. Supporting the wheel bear-
ing carrier before disconnecting the
shoclc absorber
mounting fastenerprevents damage to the brake hose, park-
ing
brake cable and drive axle CVjoints.
- Model with air shock absorbers: Detach air supply line from
shoclc absorber. Plug ports and lines to keep out dirt.
- Sport Wagon model: Remove shock absorber lower mount-
ing bolt.
4 Remove stabilizer bar link mounting nut (arrow). Press link
out of swing arm.
Model with air springs: Disable air supply pump by discon-
necting electrical plug before performing any repairs. Pump is
located beneath a cover under
the spare tire in the floor of the
carao
comoartment.
4 Model with air springs: Loosen compressed air pipes (ar-
rows) at air distribution assembly to release system pres.
sure.
WARNING-
Vehicle will lower when the air pipes are opened.
- Models with rear coil springs: Remove cargo compartment
floor carpet.

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330-24
Rear Suspension
4 Working from underneath, position BMW special tool 33 2
301 between 2nd and 3rd spring coil from bottom.
Make sure tool recess faces upward.
Working in cargo compartment, guide BMW special tool 33
2 304 from above and thread into special tool 33 2 301.
4 Working in cargo compartment, attach BMW special tools 33
2 302, 33 2 303 and 33 2 305 to special tool 33 2 304.
Use special tool 33
2 306 to compress spring.
Tighten until lower spring coil lifts off spring seat on wheel
bearing carrier.
4 Models with air springs: Loosen compressed air pipes (ar-
rows) at air distribution assembly to release system pres-
sure.
WARNING -
Vehicle will lower when the air pipes are opened. 1
- Support wheel bearing carrier from below.
CAUTION-
The shock absorber prevents the drive axle and wheel bear-
ing carrier from dropping too far. Supporting the wheel bear-
ing carrier before disconnecting the shock absorber
mounting iastenerprevents damage to the brake hose,
parl-
ino brake cable and drive axle CV ioints.
- Models with air shock absorbers: Detach air supply line from
shock absorber. Plug ports and lines to keep out dirt.
- Remove shoclc absorber lower mounting bolt

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---
Rear Suspension
ELECTRONIC HEIGHT CONTROL
(EHC) COMPONENT REPLACEMENT
Sport Premium rear suspension is an option on Sport Wagon
models and standard on
1999 and later V-8 Sport Wagons.
This suspension incorporates electronic height control
(EHC)
using air springs.
With vehicle lifted off the ground,
if the rear air springs can be
compressed by hand, either the spring is defective or the sys-
tem is depressurized.
Locate
EHC faults using BMW scan tools DIS or MoDiC. EHC
description and some troubleshooting is covered in 300 Sus-
pension, Steering and Brakes-General.
Air spring replacement is covered earlier in this chapter. See
Air spring, removing and installing.
CAUTION-
Maintain high levels of cleanliness around air line connec-
tions when disassembling and assembling air suspension
components. Even
small dirt particles can cause leakage in
the pressurized system.
Electronic height control
(EHC) components
1. Air spring
2. 1 liter air reservoir
3. EHC control module
4. Air supply distributor
5. Airsupply pump
(under spare tire)
6. Air spring mounting bolt
(at wheel bearing carrier)
7. Rear ride height sensors
(Hall effect)
8. Air supply pump relay

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340-6
1 Brakes
Brake system troubleshooting
/symptom I Probable cause 1 Repairs
Brake squeal
Pedal goes to floor when
bralting
Low pedal after system bleeding
Pedal spongy or brakes work
only when pedal is pumped
Excessive braking effort
Brakes pulsate, chatter or grab
Uneven
bralting, car pulls to one
side, rear braltes
loclt
Brakes drag, bind or overheat Brake
pad carriers dirty or corroded or
pads loose (poor fit) in pad carrier
Braite pads heat-glazed or oil-soaked
Wheel bearings worn (noise most
pronounced when turning)
Incorrectly Installed brake pads,
parking bralte shoes, or bralte parts
Brake fluid loss due to system leaks
Master cylinder or traction control
system faulty
Master cylinder faulty
Air in braite fluid
Master cylinder or traction control
system faulty
Brake pads wet
Brake pads
heat-glazedorfluid-soalted
Vacuum booster or vacuum hose
connections to booster faulty
--- Warped brake rotors
Brake pads worn
Brake pads heat-glazed or oil-soaked Remove
brake pads and clean calipers. Use original
equipment pads for proper fit and use BMW anti-squeal
compound during installation,
Replace brake pads. Ciean rotors. Replace leaking caliper:
as required.
Replace worn bearings. See 310 Front Suspension
or33C
Rear Suspension.
Check component installation. Checldreplace anti-rattle
springs.
Checlt fluid level and inspect for signs of leakage.
Replace master cylinder. Diagnose traction control system
using factory or compatible diagnostic tool.
Replace master cylinder.
Bleed system using factory or compatible diagnostic tool.
Replace master cylinder. Diagnose traction control system
using factory or compatible diagnostic tool.
Use light pedal pressure to dry pads while driving.
Replace
bralte pads and rotors. Replace leaking calipers.
lnspect vacuum lines. Test vacuum booster and replace as
required. Test vacuum non-return valve for one-way flow.
Resurface or replace rotors.
Replace brake pads.
Clean rotors. Replace leaiting calipers.
Incorrect tire pressures or worn tires
Brake pads on one side of car heat-
glazed or fluid-soaked
Caliper or brake pads binding
Worn suspension components
Brake caliper or brake pads binding
Master cylinder or traction control
system faulty lnspect
tire condition. Checlt and correct tire pressures.
Replace brake pads. Clean rotors. Replace leaking
calipers.
Clean and recondition brakes.
Inspect for worn or damaged suspension components. See
310 Front Suspension or 330 Rear Suspension.
Ciean or replace caliper.
Replace master cylinder. Diagnose traction control system
using faclory or compatible diagnostic tool.

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Brakes
Warnings and cautions
WARNING-
. E39 cars require special BMWsen/ice equipment toprop-
erly bleed the brake hydraulic system. See Bleeding
Brakes for additional information.
Semi-metallic and metallic brake friction materials in
brake pads or shoes may produce dangerous dust.
Brake fluid is poisonous, corrosive and dangerous to
the environment. Wear safety glasses and rubber
gloves when worliing with
bralie fluid. Do not siphon
brake fluid with your mouth. Dispose of brake fluid
properly
Do not reuse self-locking nuts, bolts or fasteners. They
are designed to be used only once and may fail if re-
used. Always replace them with new self-locliing fas-
teners.
CAUTlOI\C
Immediately clean bralie fluid spilled on painted surfaces
and wash with water, as
bralie 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
braking sys-
tem, and will also lower the fluid boiling point.
. Plug open lines and brake fluid ports to prevent con-
tamination.
Only tighten brake hoses on front wheels
with wheels
in straight ahead position.
If carrying out electric welding
worlc, be sure to discon-
nect electrical harness connector from electronic con-
trol module.
Do not expose electronic control modules to high sus-
tained heat, such as in a paint drying booth. Maximum
heat exposure:-95°C (203
OF) for short periods of time-
85'C (185°F) for Ions periods of time (approx. 2 hours)

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340-8
1 Brakes
Brake bleeding is usually done for one of two reasons: either
to replace old brake fluid as part of routine maintenance or to
expel trapped air in the system that resulted
from opening the
brake hydraulic system during repairs.
Read the
Warnings listed below before beginning the bleed-
ing procedure an on any
E39 car. If air enters the ACS or DSC
hydraulic unit, the factory BMW Service Tester MUST be
used in conjunction with a bralte pressure bleeder before the
vehicle is driven.
The BMW
ServiceTester (DISpluslGT1iMoDiC) must be
used to bleed the braltes if:
Any hydraulic brake system components are replaced, in-
cluding bralte lines.
Air has enter the
ABSIASC or ABSlDSC hydraulic unit.
WARNING -
* The ASC and DSC systems use electronic controls and a
sophisticated hydraulic unit Once air enters the hydraulic
unit, it is very difficult to remove using traditional methods.
For this reason, pressure
brake bleeding should be done
in conjunction with the BMW
Sewice Tester (DIS-
plus/GTl/MoDiC). The tester electrically cycles the hy-
draulic unit solenoids in the hydraulic unit while
pressurized brake fluid is forced through the system.
When flushing the brake fluid from the system, use ex-
treme care to not let the
brale fluid reservoir run dry If
air enters the hydraulic unit, the BMW Service Tester
MUST be used to bleed the brale system before the
vehicle is driven.
Always use new brake fluid from an unopened container. It is
important to bleed the entire system when any part of the hy-
draulic system has been opened. Be sure to have the special
equipment needed before beginning the job.
When bleeding the
braltes, start atthe wheel farthest from the
master cylinder and progress in the following order:
right rear brake
left rear brake
* right front brake
left front brake

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Brakes
Master cylinder, removing and installing
CAUTlOI\C
Brake fluid is highly corrosive and dangerous to the environ-
ment. Dispose of it properly.
4 Remove left side interior ventilation microfilter housing:
Remove upper cover and microfilter locking clip
(A).
- Release locking clamp (B), and rotate air tube in direction
of arrow to remove.
Disconnect wiring harness from hood switch
(C).
Release filter body mounting clamp (D) and remove lower
microfilter housing.
4 Remove side trim panel from left rear of engine compartment
by releasing clips
(arrows).
4 Disconnect bralte fluid level sensor connector (A) from fluid
reservoir. Remove reservoir cap.
. Using a clean syringe, empty bralte fluid reservoir.
Where applicable, disconnect hydraulic clutch system sup-
ply line from fluid reservoir duct
(5). Keep supply line sup-
ported and above clutch master cylinder to prevent air
bubbles from reaching clutch hydraulic system.
Where applicable, disconnect DSC system precharge
pump supply line from fluid reservoir duct
(C). Secure sup-
ply line in vertical position to prevent fluid loss.
Plug open brake fluid lines and ducts to prevent fluid leak-
age or contamination.
- Remove brake fluid reservoir by tilting sideways.

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.- -
Brakes
Disconnect master cylinder brake lines (A)
Plug open brake lines to prevent contamination.
Remove master cylinder mounting nuts
(6) and remove
cylinder.
NOTE-
It may be necessary to remove the brake booster with master
cylinder attached due to limited access.
Bralce master cylin-
dercan then be removed from booster. See Brake booster,
removing and installing later
in this repair group.
- During reinstallation, make sure all nuts, fluid couplings,
thread bores, and mating surfaces are clean.
- Mount master cylinder to bralte booster using new sealing O-
ring and new self-locking nuts.
CAUTIOI\C
* Be sure to align master cylinderpushrod and booster
pushrod.
* Do not over-torque master cylinder mounting nuts. This
could damage the brake booster and prevent proper
vacuum build-up.
Tightening torque Brake master cylinder to brake booster
26 Nm (19 ft-lb)
- Connect bralte fluid lines to master cylinder.
Tightening torque Brake fluid line to master cylinder
18 Nm (13 ft-lb)
- Carefully reinstall fluid reservoir using new sealing grommets.
- Reconnect precharge pump fluid supply hose, if applicable. -
- Reconnect hydraulic clutch fluid supply hose, if applicable.
- Remainder of installation is reverse of removal.
Top up with fresh brake fluid.
Bleed entire brake system as described earlier