1998 BMW 528i maintenance

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180-2
Exhaust System
The exhaust system is designed to be maintenance free, al-
though regular inspection is warranted due to the harsh oper-
ating conditions. Under normal conditions, the catalytic
converter does not require replacement unless it is damaged.
New fasteners, clamps, rubber mounts and gaskets should
be used when replacing exhaust components.
A liberal appli-
cation of penetrating oil to the exhaust system nuts and bolts
in advance may make removal easier.
WARNING -
The exhaust system and catalytic converter operate at
very high temperatures. Allow components to cool before
servicing. Wear protective clothing to prevent burns.
Do not use flammable chemicals near a hot
cataiyiic
converter.
Corroded exhaust system components crumble easily
and often have exposed sharp edges. To avoid injury,
wear eye protection and heavy gloves when working
Exhaust system, removing and installing
The removal and installation procedures given here are gen-
eral procedures for all models. The removal of the exhaust
system as a complete unit is recommended. Once the com-
plete system is removed from the car, individual pipes and
mufflers can be more easily replaced.
WARNING-
Exhaust gases are colorless, odorless, and very toxic. Run
the engine only in a well-ventilated area. Immediately repair
any
leaks in the exhaust system or structural damage to the
car body that
might allow exhaust gases to enter the passen-
ger compartment.
CAUTION-
Use care not to drag or bang oxygen sensors. Oxygen sen-
sors can be easily ruined.

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240-2
/ ~utomatic Transmission
This section covers maintenance and replacement of the
automatic transmission for
E39 models.
Automatic transmission internal repairs are not covered.
Such repairs require special service equipment and knowl-
edge. If it is determined that transmission internal
sewice is
required, consult an authorized BMW dealer about a factory
reconditioned unit or a transmission rebuild.
CAUTION-
ATF does not circulate unless the engine is running. When
towing an automatic transmission vehicle, use a flat bed truck
or raise the rear wheels off the ground.
Special tools
Some special tools are required for the removal and installa-
tion of an automatic transmission on the
E39 BMW models.
While these tools are not absolutely necessary, they are es-
pecially helpful when dealing with the removal and replace-
ment of the torque converter.
4 Engine support bracket
(Tool No. BMW
00 0 200.00 0 208)
4 Transmission jack
(Tool No.
BMW 00 2 030)
4 Engine support block (V-8 models) 11 7310 (Tool No. BMW 11 7 310)

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Suspension, Steering and Brakes - ~enerail
The main components of the system are the wheel speed
(pulse) sensors, the
ABSIASC or ABSIDSC control module,
and the hydraulic control unit.
Traction control also comes into operation during decelera-
tion. Decelerating on snowy or icy road surfaces can lead to
rear wheel slip. If a rear wheel starts to drag or lock up, the
ASC system can limit the problem by adjusting throttle, fuel
injection and ignition timing.
4 A switch (arrow) on the center console is used to toggle the
ASC on or off.
NOJE-
Even with the ASC system turned off, if the ASC control mod-
ule senses a difference in wheel speed (one wheel spinning)
the
ASC system applies modulated braling force to the slip-
ping wheel until traction is regained. There is no override of
fuelinjection function.
The ASC system is designed to be maintenance free. There
are no adjustments that can be made. Repair and trouble-
shooting of the ASC system requires special test equipment
and knowledge and should be performed only by an autho-
rized
BMW dealer.
ABSIASC traction
I 1.
control system
Wheel speed sensor
Wheel speed pulse wheel
Brake disk
Brake caliper
ABSIASC hydraulic unit
Brake master cylinder
Pedal operated throttle valve
ASC controlled throttle valve
Engine control module (ECM)
Accelerator pedal
ABSlASC control module

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31 0-1 8
I~ront Suspension Tension strut bushing, replacing
- Raise car and remove wheel.
WARNING-
Make sure that the caris 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.
- Remove tension strut from car as described earlier.
- Using a service press and appropriate press tools (BMW
special tools 31 2 26112621263 or equivalent), press bushing
out of tension strut.
4 Clean bushing bore and press in new bushing while aligning
mark on bushing with
rnarlt on tension strut (arrows).
CAUTION-
To avoid damaging the new bushing, press only on the outer
steel sleeve during installation.
- Press bushing in so it protrudes equally from both sides of
tension strut.
- Install tension strut as described earlier.
CAUTION-
Tighten the tension strut bushing through-bolt to its final
torque only with car on the ground and the suspension nor-
mally loaded as described earlier.
The front wheel bearings are permanently sealed and require
no maintenance. The bearing is integral with the wheel hub.
The wheel bearing and hub assembly is bolted to the steering
knuckle.
- Raise car and remove front wheel
WARNING-
Make sure that 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
susoension Darts.
- Unbolt brake caliper and hang to side with stiff wire. Do not
disconnect bralte hose. Remove bralte disc. See
340
Brakes.

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I Steerina and Wheel Alianment
Steering
system
Two types of steering gear are used in the E39 series models.
6-cylinder
(5251, 528i and 530i) models are equipped with
rack and pinion steering. The steering rack is mounted to
an aluminum subframe.
V-8
(540i) models are equipped with a recirculating ball
and nut steering gearbox mounted to a steel subframe.
At low speeds, maximum power assist is provided to ease
parking and city driving. At high speeds, assist is reduced to
ensure stability. The power steering system varies assist
based on engine speed.
Power boost for the steering is provided by an engine-driven
hydraulic pump. A hydraulic control valve is used to control
boost pressure.
The steering wheel connects to the steering gear via an ad-
justable steering column which incorporates a rubber cou-
pling ("guibo") to dampen vibration and noise.
Power steering fluid is supplied from the fluid
reservoir to the
pump and to the steering gear via rubberlmetal hoses.
The return line from the steering gear to the
reservoir loops
into the airstream in front of the radiator and connects to the
steering fluid cooler. The fluid cooler is attached to a cassette
which also includes cooling coils for engine oil, transmission
fluid and AIC condenser.
The steering gear requires no maintenance other than align-
ment and periodic inspection for worn components. Inspect
rubber rack boots
(rack and pinion system) and tie-rod end
boots periodically for tears or damage. Replace
if necessary.
-
NOTE-
The airbag system is traditionally referred to as Supplemen-
tal Restraint System (SRS). The
BMW versfon of SRS used
m the E39 models is known as the Multiple Restraint System - (MRS). - -

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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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- -
On-Board Diagnostics
Professional diagnostic scan tools available atthe time of this
printing include the BMW factory tools
(DISplus, GTI,
MoDiC) and a small number of aftermarket BMW-specific
tools. See
020 Maintenance.
In addition to the professional line of scan tools, inexpensive
generic OBD
II scan tool software programs and handheld
units are readily available. Though limited, they are
nonetheless powerful diagnostic tools. These tools read live
data streams and freeze frame data as well as a host of other
valuable diagnostic data.
Diagnostic monitors
Diagnostic monitors run tests and checks on specific
emission control systems, components, and functions.
A complete drive cycle is requiredforthe tests to bevalid. See
Drive cycle in this repair group. The diagnostic monitor
signals the
ECM of the loss or impairment of the signal or
component and determines if a signal or sensor is faulty
based on
3 conditions:
* Signal or component shorted to ground
Signal or component shorted to
B+
Signal or component missing (open circuit)
The OBD
II system monitors all emission control systems that
are installed. Emission control systems vary by vehicle model
and year. For example, a vehicle may not be equipped with
secondary air injection, so no secondary air readiness code
would be present.
OBD
II software monitors the following:
Oxygen sensors
Catalysts
Engine misfire
- Fuel tank evaporative control system
Secondary air injection Fuel system
Oxygen sensor monitoring. When driving conditions allow,
response rate and switching time of each oxygen sensor is
monitored. The oxygen sensor heater function is also
monitored. The OBD
II system differentiates between
precataylst and post-catalyst oxygen sensors and reads each
one individually. In order
forthe oxygen sensor to be
effectively monitored, the system must be in closed loop
operation.

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OBD-6
On-Board Diagnostics
Fuel system monitoring. This monitor looks at the fuel
delivery needed (long
/short term fuel trim) for proper engine
operation based on programmed data. If too much or not
enough fuel is delivered over a predetermined time, a DTC is
set and the MIL illuminates.
Fuel trim refers to adiustments to base fuel schedule.
Lono- ., term fuel trim refers to gradual adjustments to the fuel
calibration adjustment as compared to short term fuel trim.
Long term fuel trim adjustments compensate for gradual
changes that occur over time.
Fuel system monitoring monitors the calculated injection time
(ti) in relation to enginespeed, load and precatalyticconverter
oxygen
sensor(s) signals.
Using this data, the system optimizes fuel delivery for all
engine operating conditions.
Evaporative system monitoring. This monitor checks the
the fuel storage system and related fuel lines for leaks. It can
detect very small leaks anywhere in the system.
A leak detection unit (LDP or DMTL) is used to pressurize the
evaporative control system on a continuous basis (as the
drive cycle allows) and to
check system integrity.
Drive cycle
The OED II drive cycle is an important concept in
understanding OBD
II requirements. The purpose of the drive
cycle is to run ail of the emission-related on-board diagnostics
over a broad range of driving conditions.
A drive cycle is considered complete when all of the
diagnostic monitors have run their tests without interruption.
~ora drive cycle to be initiated, the vehicle must be started
cold and brought up to
1 60°F and at least 40°F above its
original starting temperature.
Readiness codes
Inspection/maintenance (I/M) readiness codes are mandated
as part of OBD
II. The readiness code is stored aftercomplete
diagnostic monitoring of specified components and systems
is carried out. The readiness code function was designed to
prevent manipulating an
I/M emission test procedure by
clearing faults codes or disconnecting the ECM or battery.