1997 BMW 323i spark plugs

Solt
Diameter
and
Wrench
Size
"
M5
.
...
............
....
......
.
.......
8
mm

"
M6
.
.
..............
.
.
...
...........
.10
mm

"
M8
.
.
..............
.
.
..
.....
12mmor13mm

"
M10
..
.............
.
.
...
...........
.17
mm

"
M12
...
...........
..
.
..
............
.19
mm

"
M14
.
..:
.
.........
..
.
..
.............
22
mm

Spark
Plug
Socket
.
A
special
socket
for
spark
plugs
is
the

correct
size,
is
deep
enough
to
accommodate
a
spark
plug's

length,
and
includes
a
rubber
insertto
both
protect
the
spark

plug
from
damage
and
grip
it
for
easier
removal
.
See
Fig
.
9
.

Fig
.
9
.



Spark
plug
socket
.

FUNDAMENTALS
FOR
THEDO-ITYOURSELF
OWNER
010-
9

B003FNG

Pliers
.
A
few
of
the
many
types
ofpliers
are
shown
in
Fig
.
10
.

Mostare
used
for
holding
irregularobjects,
bending,or
crimp-

ing
.
Some
have
special
applications
.

A
needlenose
plier
is
used
for
gripping
small
and
poorly
ac-

cessible
objects,
and
is
useful
for
wiring
and
other
electrical

work
.
A
locking
plier
suchas
theVise-Grip
®
is
useful
because

of
its
tightgrip
.

Snap-ring
and
circlip
pliers
withspecial
tipped
jacas
areused
lo
remove
and
install
snap-ringsor
circlips
.
A
Channel-lock®
or
water
pump
plier
has
adjustable
jacas
that
can
be
quickly

changed
to
match
the
size
of
the
object
being
held
to
give
great-
erleverage
.

An
adjustable
wrench
canbea
useful
addition
to
a
small
tool

kit
.
See
Fig
.
11
.
It
can
substitute
in
a
pinch,
if
two
wrenches
of

the
same
size
are
needed
lo
remove
a
nut
and
bolt
.
Use
extra
care
with
adjustable
wrenches,
as
they
tend
to
loosen,
slip,
and
damage
fasteners
.

Fig
.
11
.
Adjustable
wrench
.

B008FNG

Compared
to
a
wrench
of
the
correct
size,
an
adjustable

wrench
is
always
second
best
.
They
shouldonly
beused
when

the
correct
size
wrench
is
not
available
.
Choose
one
of
average

size
range,
about
6
to
8
inches
in
length
.

Jack
Stands

Strong
jack
stands
are
extremely
important
for
any
work
that

is
done
under
thecar
.
Use
onlyjack
stands
that
are
designed

for
the
purpose
.
Blocks
of
wood,
concrete,
bricks,
etc
.
arenot

safeor
suitable
substitutes
.

WARNING
-

A
jack
should
be
used
only
to
raise
the
vehicle
and
shouldnot
beused
to
support
the
car
for
a
long
pe-
riod
.
Always
use
jack
stands
to
support
a
raised
ve-
hicle
.

Jack
standsare
available
1n
severa¡
styles
.
A
typical
jack

stand
is
shown
in
Fig
.
12
.
The
best
ones
are
made
of
heavy
ma-

terial
for
strength,
have
a
wide
base
for
stability,
and
are

equipped
lo
positively
lock
in
their
raised
positions
.
Get
the
best

ones
available
.

Oil
Change
Equipment

Changing
engine
oil
requires
a
17mm
socket
or
wrench
to

BOO6FNG-



loosen
and
tighten
the
drain
plug
and
a
drain
pan
(at
least
8
qt
.

capacity)
.
An
oil
filter
wrench
is
not
required
.
These
items
are
Fig
.
10
.
Pliers
.
From
left,
snap-ring,



needlenose,
adjustable-joint



shown
in
Fig
.
13
.
A
wide,
loca
drain
pan
wíll
fit
more
easily
under

(Channellock©),
slip-joint,
and
locking(Vise-Grip®)
.



the
car
.
Use
a
funnel
lo
pour
the
new
oil
into
theengine
.

TOOLS

020
Maintenance
Program

GENERAL
.
.
...
.
.
.
...
.
.
.
.
.
.
.
.
.
.
.
...
.
..
020-2

BMW
Service
Indicator
......
..
....
..
...
..
.
020-2

Oil
Service
.....
.
..........
..
...
...
...
..
.
020-2

Inspection
I
and
Inspection
II
.
..
....
..
...
..
.
020-2

Resetting
Service
Indicator
....
.
....
..
...
..
.
020-3

MAINTENANCE
TABLES
..
.
.
.
.
.
........
020-3

FLUID
AND
LUBRICANT

SPECIFICATIONS
.
.
.
.
.
.
.
...
.
.
.
....
.
...
020-8

Manual
Transmission
Fluid
..
.
.
.
.
.
....
.
.
.
.
020-8

Automatic
Transmission
Fluid
.
.
.
.
.
....
.
.
.
.
020-8

Final
Drive
Gear
Oil
................
.
.
.
.
020-9
Brake
Fluid
.
.
.
.
.
................
.
.
.
.
020-9
Engine
Coolant
(Anti-freeze)
.
.
...
.
....
.
.
.
.
020-9

Power
Steering
Fluid
........
..
......
.
.
.
.
020-9

ENGINE
OIL
SERVICE
.
.
...
.
.
.
...
.
.
.
.
.
.
020-9

Engine
oil,
checking
leve¡
..
...
...
..
........
020-9
Engine
oil
and
filter,
changing
....
.
......
.
..
020-9

ENGINE
COMPARTMENT

MAINTENANCE
...
.
.
.
.
.
.
.
.
.
.
.
.
.
......
020-10

Air
filter,
replacing
.
...
...
.
.....
.
.....
.
...
020-11

Spark
plugs,
replacing
...
.
......
.
...
..
...
020-11

¡dle
Speed
.
..
...
...
....
.
......
.
...
..
...
020-12

Battery,
checking
and
cleaning
.......
..
...
020-12

Battery,
replacing
.
.....
.
.....
.
.....
..
...
020-12

Accelerator
and
Throttle
Linkage
.
.....
..
...
020-13

Engine
DriveBelts
.....
.
....
..
...
...
...
.
020-13

V-belt,
replacing

(4-cylinder
engines
built
up
to
1/94)
..
....
.
020-13

Poly-ribbed
belt,
replacing

(4-cylinder
engines
built
from
1194

and
all
6-cylinder
engines)
.
.
....
..
......
020-13

Cooling
System
Service
.
...
..
....
..
....
..
020-14

Power
steering
fluid,
checking
leve¡
.
..
....
.
.
020-14

Oxygen
Sensors
....
...
..
..
....



.
.....
.
.
020-15

MAINTENANCE
PROGRAM



020-1

UNDER-CAR
MAINTENANCE
.
..
.
...
.
.
.020-16
'

Fuel
filter,
replacing
...
.
.....
..
.....
..
..
.020-16

Tires,
checking
inflation
pressure
.
.....
.
....
020-17

Tires,
rotating
...
..
.....
..
....
..
....
.
....
020-17

Wheels,
aligning
..
.....
.
...........
.
....
'020-17

Brake
system,
inspecting
.
.
....
.
.....
..
...
020-17

Brake
pad/rotor
wear,checking
.
......
.
....
020-17

Brake
fluid,
replacing
.........
..
.



..
..



.
020-17

Parking
brake,
checking
......
.
.....
..
....
020-17

Exhaust
system,
inspecting
....
..
.....
.
...
.020-18

Manual
Transmission
Senrice
..
..
.....
.
....
020-18

Manual
transmission
fluida

checking
and
filling
..
.
....
..



.
.
..
..
....
020-18

AutomaticTransmission
Service
.
....
...
....
020-18

Front
suspension
and
steeringlinkages,
inspecting
..
.
:.....
.
....
..
.....
..
...
.
.020-18

Rear
suspension,
inspecting
.
..
...
...
....
..
020-18

Final
drive
oil
leve¡,
checking
.
.
.
...
....
...
..
020-18

Fuel
tank
and
fuel
lines,
inspecting
.
.....
....
020-19

Clutch
fluid,
checking
...
...
...
...
....
.....
020-19

Drive
axle
joint
boots,
inspecting
...
..
.....
..
020-19

BODY
AND
INTERIOR

MAINTENANCE
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
...
.
.020-19
Windshield
Wiper
Blade
Maintenance
....
.
.
020-19

Body
and
hinges,
lubricating
.
.....
..
......
.
020-19

Seat
Belts
...
..
...
...
...
..
.....
..
.....
.
.
020-20

Exterior
Washing
..
...
...
..
.
.
...
..
......
.020-20

Waxing
.....
..
...
...
...
..
.....
..
.......
020-20

Polishing
..
...
...
...
....
..
..........
..
.
.'020-20

Washing
Chassis
.
...
....
.
....
..
.....
.
...
020-20

Special
Cleaning
.
.
.....
..



...
.
.....
..
..
.020-20

Interior
Care
.
....
..
....
..
..



.
.
......
.
...
020-20

Leather
Upholstery
and
Trim
...
..
....
...
...
020-20

TABLES

a
.
Oil
Service
......
...
.
..
.............
...
---
020-4

b
.
Inspection
1
Service
..
.
.
.............
....
...
020-5

c
.
Inspection
11
Service
.
.
...
...........
..
.
..
..
020-6

d
.
Scheduled
Maintenance-Time/Mileage
Intervals
..
020-7

e
.
Fluids
and
Lubricants
..
...
...........
.....
..
020-8

020-6



MAINTENANCE
PROGRAM

Group
310/330

Table
c
.
Inspection
II
Service

a
d

d



a



a>



0
d

a



r



.c



mm
L



m
y



L
E

ó
3
E
ó

Maintenance
ítem



l
o-



z



~



c

Engine
compartment
maintenance

Inspect
V-belt
/Poly-ribbeddrive
condition
.
Check
V-belt
tension,
if
applicable
.

Lubricate
throttle
linkage
.

Replace
air
filter
.

Change
oil
and
oil
filter
.

Replacespark
plugs
.
Repair
Group
120

Check
brake/clutch
fluid
leve¡
.

Check
battery
acid
leve¡
and
correct
asnecessary
.
Repair
Group
121

Check
engine
coolant
leve¡
and
anti-freeze
protection
and
add
asnecessary
.
Inspect
for
cooling
system
leaks
.
Repair
Group
170

Under
car
maintenance

Change
automatic
transmission
fluid
.
Repair
Group
240

Change
manual
transmission
oil
.
Repair
Group
230

Check
clutch
plate
for
wear
.
Repair
Group
210

Check
drive
axle
boots
for
leaks
.
Repair
Group
330

Change
final
drive
fluid
(1995
and
later
models
:
change
synthetic
oil
every
2nd
Inspection
II)
.

Replace
fuel
filter
.

Check
fuel
tank,
fuel
lines,
and
af
connections
for
leaks
.

Inspect
exhaust
system
.
Repair
Group
180

Check
steering
gear
and
steering
¡inkages
.
Check
power
steering
system
for
leaks
.
Check
fluidleve¡
.
Repair
Group
320

Inspect
brake
system
for
damaged
hoses
and
lines,
leaks
or
damage
.
Remove
calipers
and
check
brake
pad
wear
.
Check
brake
rotors
for
scoring
damage
.
Repair
Group
340

Check
parking
brake
operation,
adjust
cable
if
necessary
.
Check
thickness
of
parking
brake
lin-
ings
.
Repair
Group
340

Inspect
front
and
rear
suspension,
including
front
and
rear
wheel
bearings,
for
play
.
Repair

Inspect
wheels
and
tires,
including
spare,
check
tire
pressure
and
condition
.

Body
and
Interior
Maintenance

Lubricate
door
hinges
and
hood
latch,
hood
hinges
.

Check
headlight
and
driving
light
aiming
and
adjust
asnecessary
.

Check
operation
of
headlights,
parking
lights,
back-up
lights,
licenseplate
lights,
interior
lights,
glove
box
light,
engine
compartment
light,
trunk
light,
instrument
panel
lights,
turn
signals,
emer-gency
flashers,
stop
lights,
horns,
headlight
flasher
anddimmer
switch
.

Check
active
check
control
panel
forfauits
(where
applicable)
.
6
Electrical
System

MAINTENANCE
TABLES

Continued
on
next
page

Air
filter,
replacing



Spark
plugs,
replacing

The
specified
maintenance
intervals
for
the
air
filter
are



To
access
the
spark
plugs
on
4-cylinder
engines,
remove
the

based
on
normal
use
.
If
thecar
is
operated
primarily
in
dusty



cover
fromatop
the
sparkplugs
.
See
Fig
.
10
.
Using
the
special

conditions,
the
air
filter
should
be
serviced
more
frequently
.



spark
plug
wire
removal
tool
(attached
to
rear
of
cylinder
head

beneath
engine
cover),
gently
pull
the
spark
plugwire
from
the

To
replace
the
air
filter
on
6-cylinder
engines,
unclip
and
sude



spark
plug
.
See
Fig
.
11
.
Blow
away
any
dirt
from
around
the
the
filter
cartridge
assembly
out
of
the
air
boxand
remove
the



base
of
the
plug
to
prevent
it
from
entering
theengine
.
Remove

filter
from
the
frame
assembly
.
See
Fig
.
8
.



and
install
the
spark
plugs
one
at
a
time
.

0012625

Fig
.
8
.



To
remove
air
filter
cartridge
on
6-cylinder
engines,release
fil-
ter
cartridge
at
sides
(arrows)
and
then
remove
filter
element
insert
from
cartridge
.

To
replace
the
air
filter
elementon
4-cylinder
engines,
sepa-

rate
the
upper
air
filter
housing
section
from
the
lower
section
by

unfastening
the
spring
clips
.
Remove
the
air
filter
element
from

the
air
filter
housing
.
See
Fig
.
9
.
Wipe
the
inside
of
the
air
filter

housing
clean
and
install
the
new
element
.
Reinstall
the
upper

air
filter
housing,
making
sure
that
the
two
halves
are
mated

correctly
.
Refasten
the
spring-clips
.

Fig
.
9
.



Air
filter
element
being
removed
on
4-cylinder
engine
.

MAINTENANCE
PROGRAM



020-
11

NOTE-

Spark
plug
applications
are
often
updated
and
super-
seded
from
the
original
plug
specification
.
Consuff
an
authorized
BMW
parts
department
for
the
latest
parts
_'
information
.
The
sparkplug
fisted
in
the
owners
manu-
al
may
not
be
the
latest
recommend
spark
plug,
espgp
cially
on
older
cars
.

0012631

Fig
.
10
.
To
remove
engine
cover
above
sparkpiugs
on
4-cylinder
en-
gine,
turnretainers
90°
counterclockwise
and
lift
cover
off
.

0012630

Fig
.
11
.
To
remove
spark
plugwirefrom
spark
plug
on
4-cylinder
en-

gine,
sude
special
removal
tool
over
spark
plug
wire
end
(ar-

row)
and
pull
straightoff
.
Usea
screwdriver
for
added

leverage
.
Special
tool
is
stored
at
rear
of
cylinder
head
below

top
cover
.

ENGINE
COMPARTMENT
MAINTENANCE

020-
1
2



MAINTENANCE
PROGRAM

6-cylinder
engines
use
a
coil-on-plug
configuration,
and
re-



Battery
cablesshould
be
tight
.
The
terminals,
the
cable
moval
of
thetop
engine
cover
(between
the
camshafts)
and
ig-



clamps,
and
the
battery
case
should
be
freeof
the
white
deposits
nition
cofs
are
necessary
.
See
Fig
.
12
.
Blow
away
any
dust
or



that
indicate
corrosion
and
acid
salts
.
Even
a
thin
¡ayer
of
dust
dirt
around
the
ignition
coils,
and
then
remove
the
coils
.
Blow



containing
conductive
acid
salts
can
cause
battery
discharge
.
away
any
dustor
dirt
around
the
sparkplugs
.
Remove
the
spark

plugs
.



To
remove
battery
corrosion,
begin
by
disconnecting
theca-

bles
.
Disconnect
the
negative
(-)
cable
first
.
Clean
the
terminal

posts
and
the
cable
clamps
with
a
wire
brush
.
Clean
the
main
chassis
ground
terminal
next
to
the
battery
.
Corrosion
can
be
washedaway
with
a
baking
soda
and
water
solution
that
will
neutralize
the
acid
.
Apply
the
solution
carefully,
though,since
ít
will
also
neutralize
the
acid
inside
the
battery
.
Reconnect
the
ca-
ble
clamps,
positive
(+)
cable
first
.
Lightly
coat
the
outside
of
the

terminals,
hold
down
screws,
and
clamps
with
petroleum
jelly,
grease,
or
a
commercial
battery
terminal
corrosion
inhibitor
.

Fig
.
12
.
Ignition
coil
being
removed
from
spark
plug
on
M52
engine
.

NOTE-

If
necessary,
see
120
Ignition
System
for
more
details
on
coil
removal
.

B11004

Lightlylubricate
the
new
spark
plug
threads
with
a
small
amount
of
anti-seize
compound
.
Thread
the
plugs
into
the
cyl-
inder
head
byhand
to
prevent
cross-threading
.

Tightening
Torque

"
Spark
plug
to
cylinder
head
.......
25
Nm
(18
ft-ib)

Idie
Speed

Engine
¡dle
speed
canchange
due
to
a
number
of
factors,
in-
cluding
normal
wear
.
The
idle
speed
is
electronically
adaptive
and
non-adjustable
.
See
130
Fuel
Injection
for
more
information
.

Battery,
checking
and
cleaning

The
battery
is
located
in
the
right
side
of
the
luggage
com-
partment
.
Simple
maintenance
of
the
battery
and
its
terminal
connections
will
ensure
maximum
starting
performance,
espe-
cially
in
winter
when
colder
temperaturesreduce
battery
power
.

ENGINE
COMPARTMENT
MAINTENANCE

WARNING
-

"
Prior
to
disconnecting
the
battery,
read
the
bat-
tery
disconnection
cautions
given
at
the
front
of
this
manualonpage
viii
.

"
Battery
acid
is
extremely
dangerous
.
Take
care
to
keep
it
from
contacting
eyes,
skin,
or
clothing
.
Wear
eye
protection
.
Extinguish
all
smoking
ma-
terials
and
do
not
worknear
any
oyen
flames
.

Battery
electrolyte
should
be
maintained
at
the
correct
level
just
above
the
battery
plates
and
their
separators
.
The
correct
leve¡
is
approximately
5
mm
(
1
/4
in
.)
above
thetop
of
battery
plates
orto
thetop
of
the
indicator
marks
(if
applicable)
.
The
battery
plates
and
the
indicator
marks
can
beseen
once
the
fill-
er
caps
are
removed
.
If
the
electrolyte
level
is
low,
replenish
it
by
adding
distilled
water
only
.

Battery,
repiacing

Batteries
are
rated
by
ampere
hours
(Ah),
the
number
of
hoursa
specific
current
draín
can
be
sustained
before
complete
discharge,
or
by
cold
cranking
amps
(CCA),
the
number
of
amps
available
to
crank
the
engine
in
cold
weather
conditions
.
In
general,
replacement
batteries
should
alwaysbe
rated
equal
or
higherthan
the
original
battery
.

CAUTION-

Prior
to
disconnecting
the
battery,
read
the
battery
disconnection
cautions
given
at
the
front
of
thls
manual
on
page
viii
.

The
battery
is
held
in
place
bya
single
hand
screw
and
píate
.
A
secure
battery
hold-down
is
important
in
order
to
prevent
vi-
brations
and
road
shock
from
damaging
the
battery
.

NOTE-
NOTE-
"
Always
disconnect
the
negative
()
cable
first,
and
Design
characteristics
of
the
convertible
body
cause
vi-



connect
ft
last
While
changing
batteries,
clean
away
brations
in
the
trunk
area
.
Therefore,
E36
convertibles



any
corrosion
in
or
around
the
battery
tray
.
require
a
specialbattery
designed
for
constant
vibra-
tion
.
When
repiacing
the
battery,
be
sure
the
replace-



"
Design
characteristics
of
the
convertible
body
cause
ment
is
designed
specffically
for
the
convertible
.



vibrations
to
oscillate
in
the
trunk
area
.
Therefore,
the
convertible
model
uses
a
specialbattery
designed
for
this
constant
vibration
.

ignition

Table
b
.
Engine
Management
Systems



engine
has
high
mileage
.

Engine



1
System

4-cylinder
engines
M42
(1992-1995)



Bosch
DME
Ml
.7
M44
(1996-1998)



Bosch
DME
M5
.2
(OBD
II)

6-cylinder
engines
M50
(1992)



Bosch
DME
M3
.1
M50
VANOS
(1993-1995)



Bosch
DME
M3
.3
.1
M52
(1996-1998)



Siemens
MS41
.1
(OBD
II)
S50US
(1995)



Bosch
DME
M3
.3
.1
S52US
(1996-1998)



Siemens
MS41
.1
(OBD
II)

Both
the
4-cylinder
and
6-cylinder
engines
use
a
distributor-

less
ignition
system
with
individual
ignition
coils
for
each
cylin-

der
.

FuelDelivery

Pressurized
fuel
from
the
in-tank
fuel
pump
is
injected
via

solenoid-type
fuel
injectors
.
The
ECM
controls
the
opening

and
closing
of
the
injectors
by
switchingthe
ground
side
of

each
injector
circuit
.
The
exact
amount
of
fuel
injected
is
de-

termined
by
the
amount
of
timethe
injectors
are
open
.

Cooling
System

Whenever
the
engine
is
running,
acoolant
pump
circulates

coolant
through
the
engine
and,
if
either
heater
control
valves

are
open,
through
the
heater
core
in
the
passenger
compart-

ment
.
The
coolant
absorbs
excess
heat
and
carries
it
to
the
ra-

diator
where
it
is
transferred
into
the
passing
airstream
.
A

thermostat
controls
the
flow
of
coolant
through
the
radiator

based
on
engine
temperature
.

Lubrication
System

The
lubrication
system
is
pressurized
whenever
theengine

is
running
.
The
oil
pump
draws
oil
through
a
pickup
in
the
bot-

tom
of
the
oil
pan,thenforces
it
through
a
replaceable
oil
filter

and
finto
the
engine
oíi
passages
.

On
4-cylinder
engines,
the
oil
pump
is
mounted
to
the
front

engine
cover
.
On
6-cylinder
engines,thechain-driven
oil

pump
is
bolted
to
the
bottom
of
the
cylinder
block
.

A
pressure
relief
valve
limits
the
maximum
system
pres-

sure
.
A
bypass
valve
prevents
the
oil
filter
from
bursting
and

insures
engine
lubrication
should
the
filter
become
plugged
.

See
119
Lubrication
System
for
additional
information
.

ENGINE-GENERAL
100-
5

Various
versions
of
DME
systems
are
usedon
thecars
cov-



MECHANICAL
TROUBLESHOOTING
ered
by
this
manual
.
See
Table
b
.
Each
system
is
highly
adaptive
to
compensate
for
things
suchasengine
wear
and



When
troubleshooting
an
engine
that
fails
to
start
or
runs
vacuum
leaks
.



poorly,
first
check
its
mechanical
condition-particularly
if
the

Warnings
and
Cautions

For
personal
safety,
as
well
asthe
protection
of
sensitive
electronic
components,
the
following
warnings
and
cautions
must
be
adhered
to
during
all
troubleshooting,
maintenance,
and
repairwork
.

WARNING
-

"
The
ignition
system
produces
high
voltages
that
can
be
fatal
.
Avoid
contact
with
exposed
termi-
nals
anduse
extreme
caution
when
working
on
a
car
with
the
ignition
switched
on
or
the
engine
running
.

"
Do
not
touch
or
disconnect
any
high
voltage
ca-
bles
from
the
coil,
distributor,
orspark
plugs
while
the
engine
is
running
or
being
cranked
by
the
starter

"
Connect
and
disconnect
the
engine
manage-
ment
system
wiring
and
test
equipment
leads
only
when
the
ignition
is
switched
off
.

"
Gasoline
is
highly
flammable
and
its
vapors
are
explosive
.
Do
not
smoke
or
work
on
a
car
near
heaters
or
other
fire
hazards
when
diagnosing
and
repairing
fuel
system
problems
.
Have
a
fire
extínguisher
available
in
case
of
an
emergency
.

"
Disconnecting
the
battery
may
erase
fault
code(s)
stored
in
control
module
memory
.
Using
special
BMW
diagnosnnc
equipment,
check
for
fault
codes
prior
to
disconnecting
the
battery
cables
.
If
the
Check
Engine
lightis
illuminated,
see
On-

Board
Diagnostics
(OBD)
forfault
code
infor-
mation
.
If
any
other
system
faults
havebeen
de-tected
(indicated
byan
illuminated
warning
light),
see
an
authorized
BMW
dealer
.

CAUTION-

"
Prior
to
disconnecting
the
battery,
read
the
bat-
tery
disconnection
cautions
gíven
at
the
front
of
this
manual
on
page
viii
.

"
Do
notconnect
any
test
equipment
that
delivers
a
12-volt
power
supply
to
terminal15
(+)
of
the
ignition
coil
.
The
current
flow
may
damage
the

ECM
.
In
general,
connect
test
equipment
only
as
specified
by
BMW,
this
manual,
or
the
equip-
ment
maker
.

"
Do
not
disconnect
the
battery
with
the
engine
running
.
Do
notrunthe
engine
with
any
of
the
sparkplug
wires
disconnected
.

MECHANICAL
TROUBLESHOOTING

100-6
ENGINE-GENERAL

Cylinder
compression,
checking

A
compression
tester
is
needed
to
make
a
compression
test
.

To
obtain
accurate
test
results,
the
battery
and
starter
must
be
capable
of
cranking
the
engine
at
250-300
rpm,
and
theen-

gine
should
be
at
normal
operating
temperature
.
Use
com-

pressed
air
to
clean
aroundthe
spark
plugs
before
removal
.

1
.
Disable
the
ignítion
system
by
removing
the
engine

management
system
main
relay
and
the
fuel
pump
re-
¡ay
.
See
Fig
.
6
.

WARNING
-

The
ignítion
system
produces
high
voltages
that
canbe
fatal
.
Avoid
contact
with
exposed
termínals
and

useextreme
caution
when
working
on
acar
wíth
the
ignítion
switched
on
or
the
engine
running
.

Fuel



DM
E
pump
main
re
ay



rel
ay
o
oa
ooa

.,
o00
oao

Fig
.
6
.



Engine
management
relays
in
power
distribution
box
inleft
rear
of
engine
compartment
.

CAUTION-

"
On
OBD
11
cars,
making
a
compression
test
may
causea
faultto
set
in
the
ECM
and
may
also
il-
luminate
the
Check
Engine
light
.
The
light
can
only
be
tumed
out
using
special
scan
tool
equip-
ment,using
eíther
the
BMW
specialservíce
tool
or
using
a
"generic"
OBD
11
scan
tool
.
Discon-
necting
the
battery
will
not
erase
the
fault
mem-
orynor
turn
outthe
light
.

0013034,

0012630

Fig
.
7
.



Remove
spark
plug
wires
from
spark
plugs
on
4-cylinder
en-
gine
using
special
tool
.
Tool
is
stored
under
cover
at
rear
of
cylinder
head
(arrow)
.

Fig
.
8
.



Remove
engine
cover
on
6-cylinder
engine
byprying
off
nut
covers
and
removing
nuts
(A)
.
Be
careful
not
to
let
rubber
in-
sulators
fall
off
as
cover
is
removed
(arrows)
.

4
.
On
6-cylinder
engines,
disconnect
the
harness
connec-
tors
from
the
ignítion
coils
by
lifting
the
retaining
clip
.

Remove
the
coil
mounting
nuts
andremove
the
six
coils
.
See
Fig
.
9
.
Remove
the
sparkplugs
.
"
Failure
to
remove
the
main
relay
or
attempting
to
disable
the
ignítion
system
by
other
methods
may
resultin
damage
to
the
engine
control
module
.



NOTE-

Used
sparkplugs
should
be
reinstalled
in
the
same
cyl-

2
.
On
4-cylinder
engine
:
Remove
plastic
engine
cover
from



inder
fromwhich
they
were
removed
.

top
of
cylinder
head
.
Disconnect
spark
plug
wires
and
re-
move
spark
plugs
.
See
Fig
.
7
.



5
.
Insta¡¡
the
compression
gauge
in
the
first
cylinder's

3
.
On
6-cylinder
engine
:
Remove
top
engine
coverby
pry-



spark
plug
hole,
tight
enough
to
form
a
good
seal
.

ing
off
nut
covers
and
removing
mounting
nuts
.
See
Fig
.
8
.

MECHANICAL
TROUBLESHOOTING

eiioo4

Fig
.
9
.



Remove
ignition
coils
on
6-cylinder
engine
by
disconnecting
harness
connector
and
removing
mounting
bolts
(arrows)
.

NOTE-

"
The
compression
gauge
reading
shoutd
increase
with
each
compression
stroke
and
reach
near
its
maxi-
mum
reading
in
about
4-6
strokes
.

"All
cylinders
shoutdreach
maximum
compression
in
the
same
number
of
strokes
.
If
a
cylinder
needs
sig-
nificantly
more
strokes
to
reach
maximum
compres-

sion,
there
is
a
problem
.

7
.
Release
the
pressure
at
the
compression
gauge
valve,

then
remove
the
gauge
from
the
spark
plughole
.
Re-

peat
the
test
for
each
of
the
other
cylinders
and
com-

pare
the
results
with
the
values
given
below
.

ENGINE-GENERAL
1
:00-
7

Compression
Pressure

"
Minimum
..........
.
.
..
..
10-11
bar
(142-156
psi)

"
Maximum
difference
between
cylinders
..
.....
.........
0
.5
bar
(7
psi)

Reinstall
the
spark
plugs
and
spark
plug
wires
or
ignition

cofs
.
The
remainder
of
installation
is
the
reverse
of
removal
.
Be
sure
to
reihstall
al¡
wires
disconnected
during
the
test,
especial-

¡y
ground
wires
at
the
coils
and
cylinder
head
cover
(where
ap-
plicable)
.

Tightening
Torque

"
Spark
plug
to
cylinder
head
.......
25
Nm
(18
ft-Ib)

Low
compression
indicates
a
poorly
sealed
combustion

6
.
With
the
parking
brake
set,
the
transmission
in
Park
or



chamber
.
Relatively
even
pressures
that
are
below
specification

Neutral,
and
the
accelerator
pedal
pressed
to
the
floor,



normally
indicate
worn
piston
rings
and/or
cylinder
walls
.
Erratic

crank
the
engine
with
the
starter
.
Record
the
highest



values
tend
to
indicate
valve
leakage
.
Dramatic
differences
be

value
indicated
by
the
gauge
.



tween
cylinders
are
often
the
sign
of
a
failed
head
gasket,

bumed
valve,
or
broken
piston
ring
.

Engine
Mechanical
Troubleshooting
Table

Table
c
lists
the
symptoms
of
common
engine
mechanical

problems,
their
probable
causes
and
the
suggested
corrective

actions
.
The
bold
type
indicates
the
repair
groups
where
appli-

cable
test
and
repair
procedures
can
befound
.

MECHANICAL
TROUBLESHOOTING