engine BMW 525i 1998 E39 Workshop Manual

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Brakes
Brakes, bleeding
The procedure below requires a BMW Service Tester (DIS-
pluslGTl/MoDiC).
- Determine type of traction control (ASC, DSC with precharge
pump, DSC without precharge pump). Be sure to use correct
specification brake fluid, according to application table below.
Brake fluid applications
ABS I ASC and ABS / DSC models DOT 4 brake fluid
with precharge pump (to 911998)
ABS I DSC models without precharge DOT 4 low viscosity
pump (911998 and later) brake
fluid
< Remove left side interior ventilation microfilter housing:
Remove upper cover and microfilter loclting 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.
- Top off bralte fluid in reservoir and connect BMW Service
Tester to
20 pin Data Link Connector (DLC) under hood or 16
pin
DLCIOBD I1 connector under dash.
- Call up service function Bleeding ABS / ASC or service func-
tion Bleeding ABS
/ DSC, depending on installed system.
- Fill pressure bleeding device with the correct brake fluid and
connect to brake fluid reservoir and apply pressurize.
Do not exceed a pressure of
2 bar (29 psi) when pressure
bleeding the
brake system. Excessive pressure will damage
4 Starting at right rear wheel, connect bleed hose and fluid re-
ceptacle to bleeder screw (arrow).
CA UTlON-
Bleeder hose must always remain submersed in clean brake
fluid whenever the bleeder valve is open.

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Brakes
- Open bleeder screw. Carry out bleeding procedure with
BMW Service Tester until clear, bubble-free fluid flows.
Models with DSC: After BMW Service Tester bleeding rou-
tine has finished, press brake pedal to floor
5 times until
clear, bubble-free fluid runs out. Close right rear bleeder
valve.
Models with ASC: Close right rear bleeder valve.
- Repeat procedure at left rear brakes.
- Repeat BMW Service Tester bleeding at right front brakes.
Models with DSC: After
BMW Service Tester bleeding rou-
tine has finished, press brake pedal to floor
5 times until
clear, bubble-free fluid runs out. Close right front bleeder
valve.
Models with ASC: After BMW Service Tester bleeding rou-
tine has finished, press brake pedal to floor
12 times until
clear, bubble-free fluid runs out. Close right front bleeder
valve.
- Repeat procedure at left front brakes.
- Remove brake bleeding apparatus and disconnect BMW
Service Tester. Top up brake fluid. Check to make sure
brake 1
fluid reservoir cap seal is intact.
Tightening torques Bleeder screws (wrench size)
- 7 rnrn screw
3.5 - 5 Nrn (2.5 - 3.7 ft-lb)
11 rnrn screw 12-16Nrn(9-12ft-lb)

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Brakes
BRAKE PADS, CALIPERS AND ROTORS
Brake pads,
calipers, and rotors
Braking system
components
1. Brake caliper guide bolts
2. Brake caliper
3. Brake pad wear sensor
4. Brake pad anti-rattle clip
5. Brake pads
6. Front brake rotor retaining bolts
7. Front brake rotor
8. Rear brake rotor retaining bolt
9. Rear brake rotor
10. Parking brake shoes with hard-
ware
11. Rear brake backing plate
12. Brake pad carrier
13. Brake pad carrier retaining bolts

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340-1 2
Brakes Brake pads, checking and replacing
Brake pads can be replaced without disconnecting the brake
fluid hose from the caliper or having to bleed the brakes. The
rotors can be replaced without disassembling wheel hub and
bearing. Always machine or replace rotors in pairs. Replace
pads in sets.
Front and rear brake pad replacement procedures are identical.
WARNING -
* Altllough semi-metallic andmetallic brale friction materials
in brake pads or shoes no longer contain asbestos, they
produce dangerous dust.
Treat all
brale dust as a hazardous material.
Do not create dust by grinding, sanding, or cleaning
brake friction surfaces with compressed air.
CAUTION--
Pressing caliper piston in may cause brake fluid reservoir to
overflow To prevent this, use a clean syringe to first remove
some fluid
from reservoir.
Raise car and remove wheels,
WARNING-
Make sure that the car is firmly supported on jack stands de-
signed for the purpose. Place jack stands beneath structural
chassis points. Do not place jack stands under suspension
parts.
/ 4 To measure brake pad lining thickness, insert BMW special
n 1 tool 34 1 260 at either frontilght wheel or left rear wheel -
Move wheel until notch for brake wear indicator can be
seen through wheel opening.
Insert tip of tool into notch so that the body of tool rests on
brake pad backing plate
(A), and tip touches bralte disc
(B).
Replace pads if thickness is 3.0 mm (0.12 in) or less.
Pry off
bralte calipe~ , anti-rattle spring (arrow).

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4 Remove plastic caps from caliper mounting bolts (arrows).
Use BMW special tool 34 1 080 (7 mm Alien wrench) to re-
move caliper mounting bolts. Remove caliper from pad
carri-
e r.
NOTE-
If there is a ridge on brake rotor edge, press caliper pistons
back into caliper before removing caliper.
- Check brake rotor thickness. Inspect for rust or damage. if
necessary replace or machine brake rotors as described lat-
er. Bralte rotor specifications are given in table below.
Spread bralte pads using BMW special tool
34 1 050 or
equivalent. Remove brake pads.
CA UTIOG
Pressing caliperpistons in may cause brake fluid reservoir to
overflow. To prevent this, use a clean syringe to first remove
some fluid from reservoir.
NOTE-
Inner brake pad lias a spring to locate it in the caliper piston.
4 Carefully pry pad wear sensor from brake pad
- Check caliper dust boots for damage and replace if neces-
sary.
- Clean contact surfaces between caliper and caliper carrier.
C"..., I,.. P,hi..,,,.r.. mm-*ii Ai"i,li "1.i"~"d

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340-1 4
Brakes
4 Apply a thin coating of BMW anti-squeal compound to caliper
contact face
(arrow).
Do not apply grease to brake pad backing plate.
Right Left
CAUTION-
Do not let calliper rubber dust sleeve come in contact with
anti-squeal compound. The rubber will swell and deteriorate.
4 Apply a thin coating of BMW anti-squeal compound to bralte
pad rests (arrows) on pad carrier.
4 When installing directional brake pads, install the marked
pads as shown.
NOTE-
BMW-supplied (OEM) front brake pads may be marked as di-
rectionalpads. Aftermarket brands are generally not labeled
as directional. When installing directional pads, be sure to in-
stall them as indicated in the illustration.
- Where applicable, insert brake pad wear sensor into cutout
in new pad. Push sensor into pad cutout until it locks into
place.
- -
- NOTE-
If brake lining indicator light illuminatedprior to brake pad re-
placement, replace wear sensor.
- Route pad wear sensor wiring through caliper opening and
under bleeder dust cap.

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340-1 5
Brakes
- Remainder of installation is reverse of removal.
- Clean brake caliper mounting bolts (7 mm Allen). Replace
ones which are not in perfect condition. Do not grease.
Top up brake fluid to MAX marking.
- Before driving car, pump bralte pedal several times so that
brake pads contact brake rotors.
Check that brake fluid level is correct. Top up if necessary.
Hold ignition key for at least
30 seconds in accessory po-
sition without starting engine. This clears any fault codes in
memory and turns off brake pad warning light.
Tightening torques Brake caliper to pad carrier
(7 mm Allen)
Front caliper
30 Nm (22 It-lb)
- Rear caliper 28 Nm (21 It-lb)
Road wheel to hub
120i 10 Nm (89i7 ft-lb)
Brake rotors, removing and installing
- Raise car and remove wheels
WARNING-
Male sure that the car is firmly supported on jack stands de-
signed for the purpose. Place jack stands beneath structural
chassis points. Do not place jack stands under suspension
parts.
Remove brake caliper carrier bolts (arrows). Suspend brake
caliper from chassis using stiff wire.
NOTE-
Hydraulic brake line remains connected.
4 Remove bralte rotor mounting screw (arrow) and remove ro-
tor.
- Inspect rotor for cracks, signs of overheating and scoring.
- Minimum allowable thickness (MIN TH) is stamped on rotor
hub. Measure rotor braking surface with a micrometer at
eight to ten different points and use the smallest measure-
ment. Compare to specifications in table below.
- If rotor does not pass minimum thickness requirements or is
damaged, replace rotor.

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1 Brakes
Max. machine limit per
friction ring side 0.8 mm (0.03
in) I
Brake rotor reconditioning specifications
Model
Replace
braite rotors in pairs
Bralre rotor sizes
Clean rotor with brake cleaner before installing.
Front
Model
6-cylinder
models (5251,
5281, 530i)
V-8 models (540i)
* When installing new rear brake rotors, adjust pariting brake
as described later, in Parking brake, adjusting. Rear
Vented rotor wear limit (min. thickness)
Tightening torques
Braite rotor to hub 16 Nm (12 ft-lb)
6-cylinder models
(525i, 5281, 530i)
- V-8 models (540i)
Front
296 mm (1 1.65 in)
324 mm (12.76 in)
Front bralte pad
carrler to steering ltnucitle 110 Nm (81 ft-lb)
Rear
298 mm (1 1.73 in)
Rear
brake pad carrier to wheel bearing carrier 65 Nm (48 ft-lb)
20.4
mm (0.80 in)
28.4 mm (1.12 in)
Road wheel to hub
120ilONm
(89 -t 7 it-lb)
18.4 mm (0.72 in)
The brake master cylinder is mounted to the front of the vacu-
um booster on the driverside bullthead.
-
CAUTION-
All E39 vehicles soldin the USA are equipped with Antilock
Braling System (ABS) and either Automatic Stability Control
(ASC) or Dynamic Stability Control (DSC).
In order for the
braling and stability controls to work properk if the brake
master cylinder is replaced, make sure that the brake system
is bled
by an authorized BMW dealer or other qualified repair
facility
using the BMW Service Tester. See Brake Bleeding
earlier
in this group.

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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