1999 BMW 528i belt tensioner

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170-8
I Radiator and Cooling System
Common cooling system faults can be grouped into one of 4
categories:
Cooling system
lealts
Poor coolant circulation
Radiator cooling fan faults
Electrical/electronic faults
Cooling system inspection
- Check that coolant pump drive belt tensioner is functioning
properly and that belt tension is correct. Belt tensioner sys-
tems for the different models are shown in
020 Maintenance.
- Check condition of coolant pump drive belt.
- Checlc coolant hoses for cracks or softness. Checlc clamps
for looseness. Check coolant level and check for evidence of
coolant
lealts from engine.
- Check that radiator fins are not blocked with dirt or debris.
Clean radiator using low-pressure water or compressed air.
Blow outward, from engine side out.
- To check coolant pump:
Remove mechanical cooling fan. See Mechanical
(vis.
cous clutch) cooling fan, removing and installing.
Remove drive belt from coolant pump pulley. See
020
Maintenance.
Firmly grasp opposite sides of pulley and check for play in
all directions.
Spin pulley and check that shaft runs smoothly without
play.
NOTE-
The coolant provides lubrication for the pump shaft, so an oc-
casional drop of coolant
lealing from the pump is acceptable.
If coolant drips steadily from the vent hole, replace the pump.
- At normal engine operating temperature, cooling system is
pressurized. This raises boiling point of coolant.
Leaks may
prevent system from becoming pressurized. If visual evi-
dence is inconclusive, pressure test cooling system as de-
scribed later to help pinpoint hard-to-find leaks.
- If cooling system is full of coolant and holds pressure:
- Use an appropriate scan tool to interrogate engine control
module (ECM) for radiator fan or DME control circuit faults.
Checlc for loose or worn drive belt.
0 Test for failed thermostat or coolant pump impeller. Some
pumps may be fitted with plastic impellers.

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Body-General
SAFETY AND SECURITY FEATURES
A number of new or improved safety and security features are
incorporated in
E39 cars.
Safety cage
4 The body safety cage is a continuation of an established
BMW concept for passenger protection. Tubular impact
structures built into the body provide protection against pas-
senger injury during front or rear impacts.
Door locks and door handles
4 The door handles allow easy door opening, but are secure in
accidents.
Electrical components in the locks are fully encapsulated and
cannot be picked easily. The door handles, latches and
loclc
assemblies offer reliability and security against theft.
Door position and
loclc condition are detected by hall sensors.
Roof padding
In addition to the side and head protection airbags, there is
supplementary padding at the roof pillars and along the roof
above the doors. This is positioned to present energy absorb-
ing
surlaces to passengers thrown around by side impact
forces.
Seat belts
Each front seat belt assembly has a height-adjustable anchor
at the 8-pillar.
An automatic pyrotechnic (explosive charge) tensioner tight-
ens the front belt at the buckle upon impact, snugging up lap
and shoulder segments of the belt. The tensioners are de-
signed to automatically tension the belts by about
2 inches
(55 mm) in the event ofa collision.
A force limiter puts an upper limit on the amount of iorce each
belt can exert on the passenger.

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400-8
Body-General
Airbags
Front airbags, s~de a~rbags, pyrotechnic seat belt tensioners
and the Battery Safety Terminal (BST) are integrated into the
Supplemental Restraint System (SRS) and its variants.
NOTE-
The BMW SRS system is called Multiple Restra~nt System
(MRS). Over the years,
E39 cars were equipped with MRS,
MRS
11, MRS 111. Each version offers varied features and im-
provements over the previous system.
< As many as 8 airbags may be installed in E39 cars, depend-
ing on model and MRS version.
The front
airbags operate without sodium azide propellant,
widely considered an irritant when an
airbag is deployed.
Starting with
1999 models. "smart"front passenger and driver
airbags were installed. These are of the dual-threshold, dual
stage design, including a
sensorto help prevent the unneces-
sary deployment of the passenger side
airbag if the seat is un-
occupied.
MRS control Depend~ng on options chosen, one airbag may be installed in module each door of the sedan and Sport Wagon models, protecting
passengers against
s~de impacts.
Head Protection System (ITS)
airbags strelch diagonally
across the tops of the front doors.
Airbag deployment automatically triggers fuel shutoff, turns
on the hazard and interior lights, and unlocks the doors.
- -
WARNING -
Airbags are inflated by an explosive device. Handled im-
properly or without adequate safeguards,
airbag units can
be very dangerous. Special precautions must be observed
prior to any worlc at or near any of the airbags. See
721 Air-
bag System (SRS).
Always disconnect the battery and cover the negative
(-) battery terminal with an insulator before starting di-
agnostic, troubleshooting or service work on cars fitted
with SRS, and before doing any welding on the
car.

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l Seats
Seat repair and component replacement is possible once the
seat has been removed from the vehicle.
Before servicing front seats read safety regulations on han-
dling
airbag modules and pyrotechnic seatbelt tensioners.
See
720 Seat belts and 721 Airbag system (SRS).
WARNING-
. The front seats are equipped with pyrotechnic seat belt
tensioners. These tensioners are powerful devices and
should be handled with exfreme care. Incorrect handling
can trigger off the tensioner and cause injury.
BMW recommends that all repair or replacement
worlc
on pyrotechnic devices must be carried out by a quali-
fied
BMW technician.
Be sure to disconnect the battery and wait
5 seconds
before attempting to work on pyrotechnic devices.
During body straightening and welding with an electric
arc welder, always disconnect the battery and the con-
nection to the pyrotechnic gas generators.
Seat switch and memory module, removing
and installing
- Remove front seat. See Front seats, removing and install-
ing.
- Carefully pull seat adjusting ltnobs straight out to remove.
Remove screw fastener
(A) and trim clips (B), turn side panel
downward to remove.
Disconnect electrical harness connector
(arrow).

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........... General ........................... .72 0.2 Rear Seat Belt Assembly 720-8
......... Troubleshooting ..................... .72 0.2 Rear seat belt assembly (sedan) 720-8
................ Rear seat belts (sedan) 720-9
... .......... Front Seat Assembly '720-4 Rear seat belt assembly (Sport Wagon) 720-9
Front seat belt tensioner,
......... Rear seat belts (Sport Wagon) 720-10
removing and installing ................ .72 0.4
Front seat belt assembly
.............. .72 0.6
Front seat belt reel. removing and
installing (sedan and Sport Wagon models)
.72 0.6

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I Seat Belts
This section covers repairs to the following seat belts sys-
tems. See the table below.
IMultIple Restraint Systems I
Years
311 996 - 811 997
Multiple Restraint System electronics integrate seat belt op-
erations and
airbag deployment. Airbag repair information is
covered
in 721 Airbag System (SRS).
Troubleshooting
The seat belt reel should lock when driving quicltly through
curves,
during severe braking or in case of a collision. The au-
tomatic reel does not require any servicing and should never
be opened.
- In case of an accident, follow the seat belt troubleshooting
procedures presented
in the table below.
Troubleshooting procedures
Belt creased, unraveled, pinched, cut or
melted. Belt buckle or belt loclt plastic casing Repairs
Replace complete automatic
seat belt.
Also
checlt and replace, if necessary, seat
Problem
Damage to seat
belt.
worn, damaged or missing.
Seat belt bucltle is not ejected with spring
pressure when red button on seat belt loclt is
>--- I I
Automatic belt soueaks when fastened or I~xcessive friction in belt guides. I Replace reel assembly.
Probable
cause
Accident in which bumper impact absorbers
were permanently deformed.
Seat belts aged or worn.
pressed.
Seat belt automatic reel does not lock when
pulled out suddenly.
Seat belt automatic reel jams when pulled
out.
Seat belt does not retract automatically
(see note below).
Automatic reel loose. Return sorino broken inside reel. belt mounting on car body and
seat belt
mounting on seat runner.
Replace complete automatic seat belt.
Seat belt
loclt mechanism worn or
damaged.
Tighten reel mounting bolt Replace reel assembly.
Replace seat belt lock.
Automatic reel defective.
Automatic reel loose. Return spring
broken inside reel.
Automatic reel loose.
Return spring brolten inside reel. Replace reel
assembly.
Tighten reel mounting
bolt.
Replace reel assembly.
Tighten reel mounting bolt. Replace reel assembly.
~ ~-~~ , - I'
Replace complete automatic seat belt.
Also check retaining bracket of belt
Seat belt
pyrotechnic tensioner triggered. Accident triggered pyrotechnic deployment.

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- -
Seat Belts
Front seat belt tensioner, removing and
installing
- Disconnect battery negative (-) cable in trunk.
The
front seat belt loclts are equipped with pyrotechnic (ex-
plosive charge) automatic tensioners. These tensioners are
designed to automatically retract and tension the seat belt by
55 mm (approximately 2 inches) in the event of an accident.
CAUTION-
Prior to disconnecting the battery, read the battery discon-
nection cautions given in
001 General Warnings and Cau-
tions.
WARNING-
Pyrotechnic seat belt tensioners are powerful devices and
should be handled with extreme care. Incorrect handling
can trigger the tensioner and cause injury
BMW recommends that all repair or replacement work
on pyrotechnic devices must be carried out by a quali-
fied BMW technician.
Be sure to disconnect the battery and wait
5 seconds
before attempting to work on pyrotechnic devices.
Pyrotechnic devices cannot be repaired. Always re-
place them.
Never treat pyrotechnic components with cleaning
agents or grease.
- Do not expose pyrotechnic components to tempera-
tures above
75% (167°F).
Pyrotechnic components can only be tested electrically
when installedusing the
BMWService Tester (DISplus,
GTI, or MoDiC).
Do not fire a pyrotechnic gas generatorprior to dispos-
al. It must be fired by a special disposal company or
shipped
back to BMW in the packaging of the new com-
ponent.
During body straightening and welding with an electric
arc welder, always disconnect the battery and the con-
nection to the pyrotechnic gas generators.
- Remove front seat as described in 520 Seats.
-

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Seat ~eltsl
< Remove tensioner cover:
Cut wire ties (A).
Release wiring harness from tensioner cover clip (B).
- Release tensioner cover locks (C) and slide cover down to
remove.
- When reinstalling:
Replace wire ties to relieve tension on pyrotechnic belt
ten-
sioner harness connector.
Tightening torques . -
Front seat to floor (M10) 42 Nm (31 it-lb)
Seat belt to seat 48 Nm (35 It-lb)
Tensioner mounting bracitet
to seat rail 24 Nm (18 it-lb)
Tensioner to mounting bracket 48 Nm (35 it-lb)