turning over BMW 3 SERIES 1986 E30 User Guide

6Unscrew the four nuts retaining the air
cleaner to the carburettor, and remove the
metal ring (see illustrations).
7Unscrew the nut from the mounting bracket
(see illustration).
8Lift the air cleaner from the carburettor, and
disconnect the crankcase ventilation hose
(see illustration). If necessary, prise the
sealing ring from the bottom of the air cleaner.
9Refitting is a reversal of removal, but align
the arrow on the cover with the arrow on the
inlet tube (see illustration).
Fuel injection engines
10Detach the air intake duct from the front
side of the air cleaner.11Detach the duct between the air cleaner
and the throttle body.
12Remove the air filter (see Chapter 1).
13Unplug the electrical connector from the
airflow meter (see Section 12).
14Remove the air cleaner mounting bolts
(see illustration)and lift the air cleaner
assembly from the engine compartment.
15Refitting is the reverse of removal. Ensure
that all ducts are securely refitted, or air leaks
will result.
9 Accelerator cable- check,
adjustment and renewal
1
Check
1Separate the air intake duct from the
throttle body (fuel injection models) or remove
the air cleaner (carburettor models).
2Have an assistant depress the accelerator
pedal to the floor while you watch the throttle
valve. It should move to the fully-open
position.
3Release the accelerator pedal, and make
sure the throttle valve returns smoothly to the
fully-closed position. The throttle valve should
not contact the body at any time during its
movement; if it does, the unit must be renewed.
Adjustment
4Warm the engine to normal operating
temperature, then switch it off. Depress theaccelerator pedal to the floor twice, then
check the cable free play at the
carburettor/throttle body. Compare it to the
value listed in this Chapter’s Specifications.
5If the free play isn’t as specified, adjust it by
turning the adjustment nut (see illustration).
6Have an assistant help you verify the
throttle valve is fully open when the
accelerator pedal is depressed to the floor.
Renewal
Note:The following paragraphs describe the
procedure for fuel injection engines - the
procedure is similar on carburettor engines
7Disconnect the battery negative cable.
Fuel and exhaust systems 4•9
8.6b . . . and remove the metal ring8.6a Unscrew the four air cleaner-to-
carburettor nuts . . .8.4 Air cleaner inlet duct (1) and warm-air
hose (2)
9.5 To adjust the accelerator cable free
play, hold nut B stationary and turn nut A
(fuel injection engine shown)8.14 Remove the two nuts (arrowed) from
the air cleaner assembly (Motronic system
shown), and lift it off its mountings
8.8 Disconnecting the crankcase
ventilation hose from the air cleaner8.7 Air cleaner mounting bracket nut
(arrowed)8.9 Align the air cleaner cover arrows
when refitting
4

7 Ignition timing (TCI system)-
check and adjustment
4
Warning: Keep hands, equipment
and wires well clear of the
viscous cooling fan during
adjustment of the ignition timing.
Note:This Section describes the procedure
for checking and adjusting the ignition timing
on engines fitted with the TCI system. On
engines fitted with the Motronic engine
management system, the ignition timing is
controlled by the electronic control unit, and
no adjustment is possible. The timing can be
checked using the following procedure, but no
ignition timing values were available at the
time of writing. If the timing is thought to be
incorrect, refer to a BMW dealer.
1Some special tools are required for this
procedure (see illustration). The engine must
be at normal operating temperature, and the
air conditioning (where fitted) must be
switched off. Make sure the idle speed is
correct.
2Apply the handbrake, and chock the wheels
to prevent movement of the vehicle. The
transmission must be in neutral (manual) or
Park (automatic).
3The timing marks are located on the engine
flywheel (viewed through the timing checkhole in the bellhousing) and/or on the vibration
damper on the front of the engine.
4Where applicable, disconnect the vacuum
hose from the distributor vacuum advance
unit.
5Connect a tachometer and timing light
according to the equipment manufacturer’s
instructions (an inductive pick-up timing light
is preferred). Generally, the power leads for
the timing light are attached to the battery
terminals, and the pick-up lead is attached to
the No 1 spark plug HT lead. The No 1 spark
plug is the one at the front of the engine.
Caution: If an inductive pick-up
timing light isn’t available, don’t
puncture the spark plug HT lead
to attach the timing light pick-up
lead. Instead, use an adapter between the
spark plug and HT lead. If the insulation on
the HT lead is damaged, the secondary
voltage will jump to earth at the damaged
point, and the engine will misfire.
Note:On some models, a TDC transmitter is
fitted for checking the ignition system.
However, a special BMW tester must be
connected to the diagnostic socket to use it,
so unless the special tester is available, a
conventional timing light should be used. The
ignition timing mark may be on the vibration
damper, but if not, normally the TDC mark will
be. If the timing light is of the adjustable delay
type, then the ignition timing may be
determined by zeroing the adjustment, then
turning the adjustment until the TDC marks are
aligned, and then reading off the amount of
advance from the timing light. If a standard
timing light is being used, make a mark on the
vibration damper in accordance with the
specified advance, using the following formula
to calculate the distance from the TDC mark
to the timing mark:
Distance = 2Pr x advance
360
where P = 3.142
r = radius of vibration damper
advance = specified advance
BTDC in degrees
6With the ignition off, loosen the distributor
clamp nut just enough to allow the distributor
to pivot without any slipping.7Make sure the timing light wires are routed
away from the drivebelts and fan, then start
the engine.
8Raise the engine rpm to the specified
speed, and then point the flashing timing light
at the timing marks - be very careful of moving
engine components.
9The mark on the flywheel or vibration
damper will appear stationary. If it’s aligned
with the specified point on the bellhousing or
engine front cover, the ignition timing is
correct (see illustrations).
10If the marks aren’t aligned, adjustment is
required. Turn the distributor very slowly until
the marks are aligned, taking care not to
touch the HT leads.
11Tighten the nut on the distributor clamp,
and recheck the timing.
12Switch off the engine, and remove the
timing light and tachometer. Reconnect the
vacuum hose where applicable.
8 Distributor-
removal and refitting
4
TCI system
Removal
1After carefully marking them for position,
remove the coil HT lead and spark plug HT
leads from the distributor cap (see Chapter 1).
2Remove No 1 spark plug (the one nearest
you when you are standing in front of the
engine).
3Manually rotate the engine to Top Dead
Centre (TDC) on the compression stroke for
No 1 piston (see Chapter 2A)
4Carefully mark the vacuum hoses, if more
than one is present on your distributor.
5Disconnect the vacuum hose(s).
6Disconnect the primary circuit wires from
the distributor.
7Mark the relationship of the rotor tip to the
distributor housing (see illustration). Also
mark the relationship of the distributor
housing to the engine.
5•4 Engine electrical systems
7.1 Tools for checking and adjusting the
ignition timing
1Vacuum plugs- Vacuum hoses will, in
most cases, have to be disconnected and
plugged. Moulded plugs in various shapes
and sizes can be used for this, if wished
2Inductive pick-up timing light- Flashes a
bright, concentrated beam of light when
No 1 spark plug fires. Connect the leads
according to the instructions supplied with
the light
3Distributor spanner - On some models,
the hold-down bolt for the distributor is
difficult to reach and turn with conventional
spanners or sockets. A special spanner like
this must be used
7.9a Flywheel “OT” timing mark 7.9b Flywheel “OZ” timing mark

when the transmission selector lever is in Park
or Neutral.
Always detach the battery negative cable
before working on the starting system.
19 Starter motor-
in-vehicle check
2
Note:Before diagnosing starter problems,
make sure the battery is fully charged.
1If the starter motor does not turn at all when
the switch is operated, make sure that the
gear lever is in Neutral or Park (automatic
transmission) or, where applicable, that the
clutch pedal is depressed (manual
transmission).
2Make sure that the battery is charged, and
that all cables, both at the battery and starter
solenoid terminals, are clean and secure.
3If the starter motor spins but the engine is
not cranking, the overrun clutch in the starter
motor is slipping, and the starter motor must
be renewed.
4If, when the switch is actuated, the starter
motor does not operate at all but the solenoid
clicks, then the problem lies either in the
battery, the main solenoid contacts, or the
starter motor itself (or the engine is seized).
5If the solenoid plunger cannot be heard
when the switch is actuated, the battery is
faulty, the switch is defective, the fusible link
is burned-out (the circuit is open), or the
solenoid itself is defective.
6To check the solenoid, connect a jumper
lead between the battery (+) and the ignition
switch wire terminal (the small terminal) on the
solenoid. If the starter motor now operates,
the solenoid is OK and the problem is in the
ignition switch, starter inhibitor switch
(automatic transmission models), clutch
switch (some manual transmission models), or
the wiring.
7If the starter motor still does not operate,
remove the starter/solenoid assembly for
dismantling, testing and repair.
8If the starter motor cranks the engine at an
abnormally-slow speed, first make sure that
the battery is charged, and that all terminal
connections are tight. If the engine is partially-
seized, or has the wrong viscosity oil in it, it
will crank slowly.
9Run the engine until normal operating
temperature is reached, then disconnect the
coil HT lead from the distributor cap and earth
it on the engine.
10Connect a voltmeter positive lead to the
battery positive post, and connect the
negative lead to the negative post.11Crank the engine, and take the voltmeter
readings as soon as a steady figure is
indicated. Do not allow the starter motor to
turn for more than 10 seconds at a time. A
reading of 9 volts or more, with the starter
motor turning at normal cranking speed, is
normal. If the reading is 9 volts or more but
the cranking speed is slow, the solenoid
contacts are burned, there is a bad
connection, or the starter motor itself is faulty.
If the reading is less than 9 volts and the
cranking speed is slow, the starter motor is
faulty or the battery is responsible (defective
or discharged).
20 Starter motor-
removal and refitting
1
Note:If the starter motor is defective, it should
be renewed, or taken to an auto electrical
specialist for repair. Overhaul of the starter
motor is unlikely to be a practical proposition
for the home mechanic, even if spare parts are
available. However, the solenoid can be
renewed separately (see Section 21).
Removal
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
1Detach the battery negative cable.
2Raise the vehicle and support it securely on
axle stands.
3Clearly label the wires from the terminals onthe starter motor and solenoid, then
disconnect them. Note: On some models, it
may be necessary to remove the air cleaner
(see Chapter 4), coolant expansion tank (see
Chapter 3) and the heater hoses to gain
access to the top of the starter. Carefully label
any hoses or components that need to be
removed from the engine compartment, to
avoid confusion when reassembling.
4Unscrew the mounting bolts and detach the
starter (see illustrations).
Refitting
5Refitting is the reverse of removal.
21 Starter solenoid-
removal and refitting
1
Removal
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
1Disconnect the battery negative cable.
2Remove the starter motor (see Section 20).
3Disconnect the cable from the solenoid to
the starter motor terminal.
4Remove the screws which secure the
solenoid to the starter motor.
5Detach the solenoid from the starter body.
6Remove the plunger and plunger spring.
Refitting
7Refitting is the reverse of removal.
5•12 Engine electrical systems
20.4b Withdrawing the starter motor from
the M40 engine20.4a Working under the vehicle, remove
the starter lower mounting bolt and nut
(arrowed)

6Be sure to inspect the wear sensor(s) (left
front wheel only, or left front and right rear
wheel). If they’re OK, transfer them from the
old pads to the new ones; if they’re worn by
abrasion, fit new sensors on the new pads.
7To fit the new pads, reverse the removal
procedure. When refitting the caliper, be sure
to tighten the mounting bolts to the torque
listed in this Chapter’s Specifications.
Warning: Check and if necessary
renew the mounting bolts on 3-
Series models whenever they are
removed. If in doubt, use new
bolts.
8After the job is completed, firmly depress
the brake pedal a few times, to bring the pads
into contact with the discs. The pedal shouldbe at normal height above the floor, and firm.
Check the level of the brake fluid, adding
some if necessary. Check carefully for leaks,
and check the operation of the brakes before
returning the vehicle to normal service.
9Avoid heavy braking as far as possible for
the first hundred miles or so until the new
pads have bedded in.
4 Disc brake caliper- removal,
overhaul and refitting
4
Warning: Dust created by the
brake system may contain
asbestos, which is harmful to
your health. Never blow it out
with compressed air, and don’t inhale any
of it. An approved filtering mask should be
worn when working on the brakes. Do not,
under any circumstances, use petroleum-
based solvents to clean brake parts. Use
brake system cleaner only!
Warning: Brake fluid is
poisonous. It is also an effective
paint stripper. Refer to the
warning at the start of Section 16.
Note:If an overhaul is indicated (usually
because of fluid leakage), explore all options
before beginning the job. Overhauled calipers
may be available on an exchange basis, which
makes this job quite easy. If you decide to
overhaul the calipers, make sure that anoverhaul kit is available before proceeding.
Always overhaul the calipers in pairs - never
overhaul just one of them.
Removal
1Loosen the wheel bolts, raise the front or
rear of the vehicle, and place it securely on
axle stands. Remove the wheel.
2If you’re just removing the caliper for
access to other components, it isn’t
necessary to detach the brake line. If you’re
removing the caliper for overhaul, disconnect
the brake line from the caliper, for preference
using a split ring (“brake”) spanner to protect
the fitting. Plug the line, to keep contaminants
out of the brake system and to prevent losing
brake fluid unnecessarily.
3Refer to Section 3 for the front or rear
caliper removal procedure - it’s part of the
brake pad renewal procedure. Note:The rear
caliper is similar in design to the front caliper
on 5-series models.
Overhaul
4On all calipers except the front calipers on
3-Series models, remove the circlip for the
dust seal (see illustration),then remove the
dust boot (see illustration). Before you
remove the piston, place a block of wood
between the piston and caliper to prevent
damage as it is removed.
5To remove the piston from the caliper,
apply compressed air to the brake fluid hose
connection on the caliper body (see
9•4 Braking system
3.5l Hang the caliper out of the way with a
piece of wire
3.5m Remove the outer brake pad - to fit
the new pads, reverse the removal
procedure
3.5k Unclip the inner brake pad from the
piston (5-Series)3.5j Remove the caliper and inner brake
pad (5-Series)
3.5i Depress the piston with a C-clamp
(5-Series)3.5h Prise off the anti-rattle spring
(5-Series)3.5g Remove the plugs for the brake
caliper mounting bolts, then remove the
bolts (5-Series)

adjusting screw and contract the handbrake
shoes (see illustration).
Refitting
7Ensure that the disc is completely clean
before refitting. If penetrating oil was used to
remove the disc, make sure that no trace of
this is present. Place the disc on the hub, and
refit the disc retaining screw. Tighten the
screw securely.
8Refit the caliper mounting bracket (if
removed), brake pads and caliper (see
Sections 3 and 4). Tighten all fasteners to the
torques listed in this Chapter’s Specifications.
9Refit the wheel, then lower the vehicle to
the ground. Depress the brake pedal a few
times to bring the brake pads into contact
with the disc.
10Adjust the handbrake shoes, if necessary
(Section 11).
11Check the operation of the brakes
carefully before returning the vehicle to
normal service.
6 Drum brake shoes- renewal
2
Warning: Brake shoes must be
renewed on both wheels at the
same time - never renew the
shoes on only one wheel. Also,
the dust created by the brake system may
contain asbestos, which is harmful to your
health. Never blow it out with compressed
air, and don’t inhale any of it. Always wear
an approved filtering mask when servicing
the brake system. Do not, under anycircumstances, use petroleum-based
solvents to clean brake parts. Use brake
system cleaner only.
Caution: Whenever the brake
shoes are renewed, new return
and hold-down springs and new
automatic adjuster thermo-clips
should also be fitted. Due to the
continuous heating/cooling cycle to which
the springs are subjected, they may lose
their tension over a period of time,
allowing the shoes to drag on the drum,
and wear at a much faster rate than
normal. When fitting new brake shoes, use
only original-equipment or high-quality
brand name parts.
Note 1:All four rear brake shoes must be
renewed at the same time, but to avoid mixing
up parts, work on only one brake assembly at
a time. Some rear brake components are
different for left and right-hand sides, so don’t
mix them up.
Note 2:If the wheel cylinder is found to be
leaking or otherwise defective, renew it after
removing the brake shoes. This is simply a
matter of disconnecting the hydraulic line and
unbolting the cylinder from the backplate.
Attempting to overhaul a leaking cylinder is
unlikely to be satisfactory, even if spare parts
are available.
1Chock the front wheels, then loosen the
rear wheel bolts, raise the rear of the vehicle
and place it securely on axle stands. Remove
the rear wheels and release the handbrake.
2Remove the drum retaining screw (see
illustration)and remove the drum. If the drum
is stuck to the hub, spray the area between
the hub and the drum with penetrating oil
(see illustration). If the drum still won’t come
off, the shoes have probably worn ridges into
the drum, and will have to be retracted. Insert
a narrow flat-bladed screwdriver through one
of the holes in the hub flange (see
illustration)and back off the adjuster wheel
until the drum can be removed.
3Inspect the drum for cracks, score marks,
deep scratches and hard spots, which will
appear as small discoloured areas. If the hard
spots can’t be removed with emery cloth or if
any of the other conditions exist, the drum must
be taken to a specialist to have the drum
resurfaced. Note:Professionals recommendresurfacing the drums whenever a brake job is
done. Resurfacing will eliminate the possibility
of out-of-round drums. If the drums are worn so
much that they can’t be resurfaced without
exceeding the maximum allowable diameter
(which is cast into the drum) (see illustration),
then new ones will be required. At the very least,
if you elect not to have the drums resurfaced,
remove the glazing from the surface with emery
cloth or sandpaper, using a swirling motion.
Braking system 9•7
6.2b If the drum is stuck to the hub, apply
penetrating oil around the hub/drum area,
and give it a few minutes to loosen up
any rust6.2a Removing the drum retaining screw5.6d If a rear disc still sticks to the hub,
insert a thin, flat-bladed screwdriver
through the hub flange, rotate the
starwheel on the handbrake adjusting
screw, and contract the handbrake shoes
(disc removed for clarity)
6.3 The maximum allowable inside
diameter of the drum is cast into the drum
6.2c If the brake shoes have worn a
groove in the drum and it won’t come off,
insert a thin flat-bladed screwdriver
through one of the wheel bolt holes in the
flange, and loosen the automatic adjuster
mechanism (for the sake of clarity, the
drum has already been removed in this
photo, and the screwdriver is being
inserted underneath the flange instead of
though a wheel bolt hole)
9
If the front disc is stuck, on
some discs it is possible to
thread two or three bolts into
the holes provided and
tighten them. Alternate between the
bolts, turning them a couple of turns at
a time, until the disc is free.

expel the air from the master cylinder. A large
Phillips screwdriver can be used to push on
the piston assembly.
11To prevent air from being drawn back into
the master cylinder, the plug must be refitted
and tightened down before releasing the
pressure on the piston assembly.
12Repeat the procedure until brake fluid free
of air bubbles is expelled from the brake line
outlet hole. Repeat the procedure with the
other outlet hole and plug. Be sure to keep the
master cylinder reservoir filled with brake
fluid, to prevent the introduction of air into the
system.
13High pressure is not involved in the bench
bleeding procedure, so the plugs described
above need not be refitted each time the
piston is released, if wished. Instead, before
releasing the piston, simply put your finger
tightly over the hole to keep air from being
drawn back into the master cylinder. Wait
several seconds for brake fluid to be drawn
from the reservoir into the piston bore, then
depress the piston again, removing your
finger as brake fluid is expelled. Be sure to put
your finger back over the hole each time
before releasing the piston, and when the
bleeding procedure is complete for that outlet,
refit the plug and tighten it up before going on
to the other port.
Refitting
14Refit the master cylinder (together with a
new O-ring) over the studs on the brake servo,
and tighten the mounting nuts only finger-tight
at this time.
15Thread the brake line fittings into the
master cylinder. Since the master cylinder is
still a bit loose, it can be moved slightly in
order for the fittings to thread in easily. Do not
strip the threads as the fittings are tightened.
16Tighten the brake fittings securely, and
the mounting nuts to the torque listed in this
Chapter’s Specifications.
17Fill the master cylinder reservoir with fluid,
then bleed the master cylinder (only if the
cylinder has not already been bled) and the
brake system as described in Section 16.
18To bleed the cylinder on the vehicle, have
an assistant pump the brake pedal severaltimes and then hold the pedal to the floor.
Loosen the fitting nut to allow air and fluid to
escape, then tighten the nut. Repeat this
procedure on both fittings until the fluid is
clear of air bubbles. Test the operation of the
brake system carefully before returning the
vehicle to normal service.
8 Brake vacuum servo-
check, removal and refitting
3
Operating check
1Depress the brake pedal several times with
the engine off, until there is no change in the
pedal travel.
2Depress and hold the pedal, then start the
engine. If the pedal goes down slightly,
operation is normal.
Airtightness check
3Start the engine, and turn it off after one or
two minutes. Depress the brake pedal several
times slowly. If the pedal goes down further
the first time but gradually rises after the
second or third depression, the servo is
airtight.
4Depress the brake pedal while the engine is
running, then stop the engine with the pedal
depressed. If there is no change in the pedal
travel after holding the pedal for 30 seconds,
the servo is airtight.
Removal and refitting
5Dismantling the vacuum servo requires
special tools, and cannot be performed by the
home mechanic. If a problem develops, it is
recommended that a new unit be fitted.
6Remove the master cylinder as described in
Section 7.
7Disconnect the vacuum hose from the
brake servo.
8Working in the passenger compartment,
remove the glovebox and lower left-hand trim
panels.
9Remove the clip and clevis pin to
disconnect the pushrod from the cross-shaft
lever (right-hand-drive models) or brake pedal(left-hand-drive models) (see illustration). On
left-hand-drive models, also disconnect the
brake pedal return spring.
10Remove the four mounting nuts (see
illustration)and withdraw the servo unit from
the engine compartment.
11Inspect the small foam filter (see
illustration)inside the rubber boot on the
pushrod. If the filter is clogged, it may affect
the servo’s performance. To clean the filter,
wash it in a mild soapy solution. If it’s still
dirty, renew it.
12Refitting is the reverse of the removal
procedure. Tighten the brake servo mounting
nuts to the torque listed in this Chapter’s
Specifications. Before you slide the boot into
place over the servo pushrod air filter, make
sure the notches in the filter offset the notches
in the damper by 180 degrees.
13On 3-Series models, adjust the basic
setting of the pushrod’s threaded clevis until
the dimension is correct (see illustration).
When the basic setting is correct, tighten the
locknut, then adjust the brake pedal travel and
9•10 Braking system
8.13 On 3-Series models, adjust
dimension A (the distance between the
middle of the brake lever and the
bulkhead/”firewall”) by loosening the
locknut (1) at the pushrod clevis (2) and
turning the threaded part of the pushrod
until dimension A matches the dimension
listed in this Chapter’s Specifications.
When the basic setting is correct, tighten
the locknut, then adjust the brake pedal
height and the stop-light switch
8.11 An exploded view of a typical servo
pushrod assembly
1 Boot 2 Holder 3 Damper 4 Air filter8.10 Remove the four mounting nuts
(arrows) and withdraw the servo unit from
the engine compartment
(left-hand-drive model shown)
8.9 Disconnect the brake pedal return
spring, then remove the clip and clevis pin
(arrows) to disconnect the pushrod from
the brake pedal (left-hand-drive models)

the stop-light switch (see Section 13). Note:
On right-hand-drive models, the brake pedal
in on the right-hand side of the vehicle, and is
connected to the left-hand side by a cross-
shaft. The adjustment is carried out on the
pushrod at the left-hand side, but the
dimension is measured at the pedal on the
right-hand side.
14On 5-Series models, adjust the brake
pedal height and the stop-light switch (see
Section 13).
15Refit the master cylinder (see Section 7)
and attach the vacuum hose.
16Carefully test the operation of the brakes
before returning the vehicle to normal use
9 Hydraulic brake servo-
description, removal and
refitting
3
Warning: Brake fluid is
poisonous. It is also an effective
paint stripper. Refer to the
warning at the start of Section 16.
Description
1On 5-Series E28 (“old-shape”) models, a
hydraulic brake servo system is fitted. The
servo unit, located between the brake pedal
(left-hand-drive) or cross-shaft lever (right-
hand-drive) and the master cylinder, is
operated by hydraulic pressure generated by
the power steering pump. When the engine is
running, the power steering pump supplies
hydraulic pressure to a power flow regulator/
accumulator. The regulator/accumulator
stores and regulates the pressure to the
hydraulic brake servo. When you press the
brake pedal, the pressure in the servo helps
actuate the master cylinder, reducing pedal
effort.
2The hydraulic brake servo cannot be
overhauled; if it fails, a new one must be fitted.
Testing the system requires special tools, so
even fault diagnosis is beyond the scope of
the home mechanic. If the system fails, take it
to a dealer service department or other
qualified garage for repairs.
Removal and refitting
3With the engine off, discharge the hydraulic
accumulator by depressing the brake pedal
20 times or more.
4Remove the master cylinder (see Section 7).
5Clean the area around the return and
supply line fittings, then disconnect them.
Plug the lines, to prevent dirt from entering the
system, and to prevent further fluid loss.
Caution: Even a particle of dirt
can damage the servo, so be
extremely careful to prevent dirt
from entering the system while
the lines are disconnected.
6Working from inside the passenger
compartment, remove the lower left trim
panels above the brake pedal (left-hand-drive
models) or glovebox and trim (right-hand-drive models). On left-hand-drive models, also
disconnect the pedal return spring.
7Prise off the retaining clip, and disconnect
the pushrod from the brake pedal (see
illustration 8.9) or cross-shaft lever.
8Remove the four mounting nuts and
remove the brake servo (see illus-
tration 8.10).
9Refitting is the reverse of removal. Tighten
the hydraulic lines to the torque listed in this
Chapter’s Specifications. Note:Don’t try to
tighten these fittings without a torque wrench.
If they’re loose, they can leak, which can affect
system operation; if they’re tight, they can be
damaged, and they’ll also leak. You’ll need a
crowfoot-type split ring (“brake”) attachment
for your torque wrench to tighten the fittings
properly.
10When you’re done, bleed the brake
hydraulic system (Section 16) and adjust the
brake pedal travel and the stop-light switch
(see Section 13).
10 Handbrake cable(s)- renewal
2
1Peel back the boot at the base of the
handbrake lever, and remove the handbrake
cable adjusting nut (see illustration)which
also secures the cable to the handbrake lever.There are two cables - one for each rear wheel
- and a nut for each cable. On some models, it
may be necessary to remove the centre
console completely for access.
2Raise the vehicle and support it securely on
axle stands.
3Remove the rear brake drum (see Section 6)
or rear brake disc (see Section 5).
4On rear drum models, unhook the
handbrake cable from the lever on the rear
brake shoe (see Section 6). On rear disc
models, remove the handbrake shoes and the
actuator (see Section 12) and unhook the
handbrake cable from the actuator (see
illustrations).
5On rear drum models, pull the cable and
cable conduit (tube) out of the back of the
brake backplate, then detach the cable
conduit from the cable clips on the back of
the trailing arm (it’s easier to pull out the old
cable, and fit the new cable, with the conduit
straight instead of curved). On rear disc
models, it’s unnecessary to detach the cable
conduit from the brake backplate, but it’s a
good idea to detach the conduit from the clips
and guides securing it to the trailing arm, to
take some of the bend out of the conduit.
6Working from the wheel end of the cable
conduit, pull the cable out of the conduit (see
illustration).
7Lubricate the new cable with multi-purpose
grease, then insert it into the cable conduit
Braking system 9•11
10.1 Peel back the handbrake lever boot
and remove the relevant handbrake cable
adjusting nut (both arrowed)
10.6 Pull the cable out of its conduit;
before you refit the new cable, be sure to
lubricate it with multi-purpose grease10.4b . . . then remove the pin securing the
cable to the inner cam, and remove the
inner cam
10.4a To detach the handbrake cable from
the handbrake actuator on models with rear
disc brakes, pull on the outer cam and
disconnect it from the inner cam . . .
9

6 Strut or shock absorber/coil
spring- renewal
4
Note:This section applies to all front strut
assemblies and, on 5-Series models, the rear
coil-over shock absorber assemblies.
1If the struts, shock absorbers or coil springs
exhibit the telltale signs of wear (leaking fluid,
loss of damping capability, chipped, sagging
or cracked coil springs) explore all options
before beginning any work. Strut or shock
absorber assemblies complete with springs
may be available on an exchange basis, which
eliminates much time and work. Whichever
route you choose to take, check on the cost
and availability of parts before dismantling the
vehicle.
Warning: Dismantling a strut or
coil-over shock absorber
assembly is a potentially
dangerous undertaking, and
utmost attention must be directed to the
job, or serious injury may result. Use only a
high-quality spring compressor, and
carefully follow the manufacturer’s
instructions supplied with the tool. After
removing the coil spring from the strut
assembly, set it aside in a safe, isolated
area.
2Remove the strut or shock absorber
assembly (see Section 5 or 11). Mount the
assembly in a vice. Line the vice jaws with
wood or rags to prevent damage to the unit,
and don’t tighten the vice excessively.
3Following the tool manufacturer’s
instructions, fit the spring compressor (these
can be obtained at most car accessory shops,
or it may be possible to hire one) on the
spring, and compress it sufficiently to relieve
all pressure from the suspension support (see
illustration). This can be verified by wiggling
the spring.
4Prise the protective cap off the damper rod
self-locking nut. Loosen the nut (see
illustration)with a spanner while holding thedamper rod stationary with another spanner
or an Allen key.
5Remove the nut, the strut bearing, the
insulator and the large washer. Check the
bearing for smooth operation. If it doesn’t turn
smoothly, renew it. Check the rubber insulator
for cracking and general deterioration. If there
is any separation of the rubber, renew the
insulator.
6Lift off the spring retainer and the rubber
ring at the top of the spring. Check the rubber
ring for cracking and hardness. Renew it if
necessary.
7Carefully lift the compressed spring from
the assembly and set it in a safe place, such
as a steel cabinet.
Warning: Never place your head
near the end of the spring!
8Slide the protective tube and rubber
bumper off the damper rod. If either is
damaged or worn, renew it.
9If you’re working on a front strut, loosen
and remove the threaded collar (see
illustration)and pull the old strut cartridge
from the strut housing. Pour the old oil from
the strut housing.
10On all struts except gas-charged units, fill
the strut housing with 20 to 25 cc (3-Series),
42 to 47 cc (518i and 520i 5-Series models) or
20 to 25 cc (all other 5-Series models) ofengine oil (the oil helps cool the shock
absorber by transferring heat to the strut
housing). Note:It doesn’t matter what
viscosity or grade of engine oil is used.
11Refitting is otherwise the reverse of
removal. Tighten the threaded collar to the
torque listed in this Chapter’s Specifications.
Make sure you align the end of the coil spring
with the shoulder of the rubber ring and with
the spring retainer (see illustration). Tighten
the damper rod nut to the torque listed in this
Chapter’s Specifications.
12Refit the strut or shock absorber
assembly (see Section 5 or 11).
7 Balljoints- check and renewal
3
Check
Note:On 3-Series models, there are two
balljoints on each control arm - one between
the middle of the arm and the subframe, and
the other between the outer end of the arm
and the steering knuckle. On 5-Series models,
there are balljoints on the outer ends of the
control arm and the thrust arm.
1Raise the vehicle and support it securely on
axle stands.
2Visually inspect the rubber boot between
the balljoint and the subframe or steering
knuckle, etc for cuts, tears or leaking grease.
If you note any of these conditions, renew the
control arm or thrust arm - the balljoints are
not available separately.
3Place a large lever under the balljoint, and
try to push the balljoint up. Next, position the
lever between the arm and the subframe or
between the arm and steering knuckle. If you
can see or feel any movement during either
check, a worn balljoint is indicated.
4Have an assistant grasp the tyre at the top
and bottom, and shake the top of the tyre with
an in-and-out motion. Touch the balljoint stud
nut. If any looseness is felt, suspect a worn
balljoint stud or a widened hole in the
subframe or steering knuckle. If the latter
Suspension and steering systems 10•7
6.4 Prise the protective cap off the
damper rod nut, and remove the large nut
(arrowed) - to prevent the damper rod from
turning, place an Allen key in the end of
the shaft6.3 Following the tool manufacturer’s
instructions, fit the spring compressor to
the spring, and compress it sufficiently to
relieve all pressure from the suspension
support
6.11 Make sure you align the end of the
coil spring with the shoulder of the rubber
ring, and with the spring retainer
6.9 Loosen and remove the threaded
collar, and pull the old strut cartridge from
the strut housing - on all struts except
gas-charged units, pour the old oil from
the strut housing. (Spring should have
been removed first!)
10

Refitting
7Refitting is the reverse of removal. Tighten
the nuts and bolts securely. Adjust the
drivebelt tension (see Chapter 1).
8Top-up the fluid level in the reservoir (see
Chapter 1) and bleed the system (see Sec-
tion 23).
23 Power steering system-
bleeding
1
1To bleed the power steering system, begin
by checking the power steering fluid level and
adding fluid if necessary (see Chapter 1).
2Raise and support the front of the vehicle
on axle stands.
3Turn the steering wheel from lock-to-lock
several times. Recheck the fluid level and top
up if necessary.
4Start the engine and run it at 1000 rpm or
less. Turn the steering wheel from lock-to-
lock again (three or four times) and recheck
the fluid level one more time. Note:On 5-Series E28 (“old-shape”) models, pump the
brake pedal five or six times before turning the
steering wheel. Once the fluid level remains
constant, continue turning the wheel back and
forth until no more bubbles appear in the fluid
in the reservoir.
5Lower the vehicle to the ground. Run the
engine and again turn the wheels from lock-
to-lock several more times. Recheck the fluid
level. Position the wheels straight-ahead.24 Steering wheel-
removal and refitting
1
Warning: If the vehicle is
equipped with an airbag, do not
attempt this procedure. Have it
performed by a dealer service
department or other qualified specialist, as
there is a risk of injury if the airbag is
accidentally triggered.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you have
the correct activation code
before disconnecting the battery.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
Removal
1Disconnect the battery negative cable.
2Using a small screwdriver, prise off the
BMW emblem in the centre of the steering
wheel.
3Remove the steering wheel nut, and mark
the relationship of the steering wheel hub to
the shaft (see illustration).
4On all 3-Series models, and on 1986 and
later 5-Series models, turn the ignition key to
the first position to unlock the ignition lock.
5Remove the steering wheel from thesteering shaft. If the wheel is difficult to
remove from the shaft, use a steering wheel
puller to remove it - don’t hammer on the
shaft.
Refitting
6Refitting is the reverse of removal. Be sure
to align the match marks you made on the
steering wheel and the shaft. Tighten the
steering wheel nut to the torque listed in this
Chapter’s Specifications.
25 Wheels and tyres-
general information
1
Note:For more information on care and
maintenance of tyres, refer to Chapter 1.
1All vehicles covered by this manual are
equipped with steel-belted radial tyres as
original equipment. Use of other types or
sizes of tyres may affect the ride and handling
of the vehicle. Don’t mix different types or
sizes of tyres, as the handling and braking
may be seriously affected. It’s recommended
that tyres be renewed in pairs on the same
axle; if only one new tyre is being fitted, be
sure it’s the same size, structure and tread
design as the other.
2Because tyre pressure has a substantial
effect on handling and wear, the pressure on
all tyres should be checked at least once a
month or before any extended trips (see
Chapter 1).
3Wheels must be renewed if they are bent,
heavily dented, leak air, or are otherwise
damaged.
4Tyre and wheel balance is important in the
overall handling, braking and performance of
the vehicle. Unbalanced wheels can adversely
affect handling and ride characteristics, as
well as tyre life. Whenever a new tyre is fitted,
the tyre and wheel should be balanced.
10•16 Suspension and steering systems
24.3 After removing the steering wheel
nut, mark the relationship of the steering
wheel to the steering shaft (arrowed) to
ensure proper alignment during
reassembly
22.6c Typical 5-Series power steering pump mounting bolts
(arrowed)22.6b . . . and mounting nut and bolt (arrowed)

26 Wheel alignment-
general information
4
Wheel alignment refers to the adjustments
made to the wheels so they are in proper
angular relationship to the suspension and the
road. Wheels that are out of proper alignment
not only affect vehicle control, but also
increase tyre wear. The front end angles
normally measured are camber, castor and
toe-in (see illustration). Front wheel toe-in is
adjustable on all models; castor is not
adjustable. Camber is only adjustable by
replacing the strut upper mount with a special
eccentric version. Toe-in is adjustable on the
rear wheels, but only by replacing the trailing
arm outer bushings with special eccentric
bushings.
Setting the proper wheel alignment is a very
exacting process, one in which complicated
and expensive equipment is necessary to
perform the job properly. Because of this, you
should have a technician with the proper
equipment perform these tasks. We will,
however, use this space to give you a basic
idea of what is involved with wheel alignment
so you can better understand the process.
Toe-inis the “turning in” of the wheels. The
purpose of a toe specification is to ensureparallel rolling of the wheels. In a vehicle with
zero toe-in, the distance between the front
edges of the wheels will be the same as the
distance between the rear edges of the
wheels. The actual amount of toe-in is
normally very small. On the front end, toe-in is
controlled by the track rod end position on the
track rod. On the rear end, toe-in can only be
adjusted by fitting special eccentric bushings
in the trailing arm outer mounting. Incorrect
toe-in will cause the tyres to wear improperly
by making them scrub against the road
surface.
Camberis the “tilting” of the wheels from
vertical, when viewed from one end of the
vehicle. When the wheels tilt out at the top, the
camber is said to be positive (+). When the
wheels tilt in at the top the camber is negative (-
). The amount of tilt is measured in degrees from
vertical, and this measurement is called the
camber angle. This angle affects the amount of
tyre tread which contacts the road, and
compensates for changes in the suspension
geometry when the vehicle is cornering or
travelling over an undulating surface.
Castoris the “tilting” of the front steering
axis from the vertical. A tilt toward the rear at
the top is positive castor; a tilt toward the
front is negative castor. Castor is not
adjustable on the vehicles covered by this
manual.
Suspension and steering systems 10•17
10
26.1 Wheel alignment details
1 A minus B = C (degrees camber)
2 E minus F = toe-in
(expressed in inches or mm)
3 G = toe-in (expressed in degrees)