1997 BMW 318i Temperature switch

Please
read
these
warnings
and
cautions

before
proceeding
with
maintenance
and
repair
work
.

WARNING-



"
Friction
materials
(such
as
brake
pads
or
shorts
or
clutchdiscs)
contain
asbestos
fibers
or
other
friction
materials
.
Do
notcreate
"
See
also
Cautionson
page
viü



dustby
grinding,
sanding,
orby
cleaning
with
compressed
air
.

"
Some
repairs
may
be
beyond
your
capability
.
If
you
lack
the



Avoid
breathing
dust
.
Breathing
any
friction
material
dust
can
lead

skills,
tools
and
equipment,
or
a
suitable
workplace
for
any
proce-



to
serious
diseases
and
may
result
in
death
.

duredescribed
in
this
manual,
we
suggestyou
leave
such
repairs



"
Batteries
give
off
explosive
hydrogen
gas
during
charging
.
to
an
authorized
BMW
dealer
service
department
or
other
quali-



Keep
sparks,
lighted
matches
and
open
flame
away
from
the
top
fied
shop
.



of
the
battery
If
hydrogen
gas
escaping
from
the
cap
vents
is

"Do
not
re-use
any
fasteners
that
are
worn
or
deformed
in
normal



ignited,
it
will
ignite
gas
trapped
in
the
cells
and
cause
the
battery

use
.
Many
fasteners
are
designed
to
be
used
only
once
and



to
explode
.

become
unreliable
and
may
fail
when
used
a
second
time
.
This



"
Connect
and
disconnect
battery
cables,
jumper
cablesora
bat-
includes,
but
is
not
limited
to,
nuts,
bolts,
washers,
self-locking
nuts
or
bolts,
circlips
and
cotterpins
.
Always
replace
these
fasteners

with
new
parts
.
"Do
not
quick-charge
the
battery
(for
boost
starting)
for
longer
"
Never
work
under
a
lifted
car
unless
it
is
solidly
supportedon



than
one
minute
.
Wait
at
least
one
minute
before
boosting
the
bat-
stands
designed
for
the
purpose
.
Do
not
support
a
car
on
cinder



tery
a
second
time
.
blocks,
hollow
tiles
or
other
props
that
may
crumble
under
contin-

uous
load
.
Never
work
under
acar
that
is
supported
solely
by
a



"Do
not
allow
battery
charging
voltage
to
exceed
16
.5
volts
.
If
the

jack
.
Never
work
under
thecar
while
the
engine
is
running
.



battery
beginsproducing
gas
or
boiling
violently,
reduce
the
charg-
ing
rate
.
Boosting
a
sulfated
battery
at
a
high
charging
rate
can
"
If
you
are
going
to
work
under
acar
on
the
ground,
make
sure



cause
an
explosion
.
that
the
ground
is
level
.
Block
the
wheels
to
keep
the
carfrom
roll-

ing
.
Disconnect
the
battery
negative
(-)
terminal
(ground
strap)to



"
The
air-conditioning
system
is
filled
with
chemical
refrigerant,

prevent
others
from
starting
thecar
while
youare
under
it
.



which
is
hazardous
.
TheA/C
system
should
be
servicedonly
by

trained
technicians
using
approved
refrigerant
recovery/recycling
"
Never
run
the
engine
unless
the
work
area
is
well
ventilated
.



equipment,
trained
in
related
safetyprecautions,
and
familiar
with
Carbon
monoxide
kills
.



regulations
governing
the
discharging
and
disposal
of
automotive

"
Finger
rings,
bracelets
and
other
jewelry
shouldbe
removed
so



chemical
refrigerants
.

tery
charger
only
with
the
ignition
switched
off,
to
prevent
sparks
.

Do
not
disconnect
the
battery
while
the
engine
is
running
.

that
theycannot
cause
electrical
shorts,
get
caught
in
running



"
Do
not
expose
any
partof
the
A/Csystem
to
high
temperatures
machinery,
or
be
crushed
by
heavy
parts
.



suchas
open
flame
.
Excessiveheat
will
increase
system
pressure

"
Tie
long
hair
behind
your
head
.
Do
not
wear
a
necktie,
a
scarf,



and
may
cause
the
system
to
burst
.

loose
clothing,
or
a
necklace
when
you
work
near
machine
tools
or



"
Some
aerosol
tire
inflators
are
highly
flammable
.
Be
extremely
running
engines
.
If
your
hair,
clothing,
or
jewelry
were
to
get
caught



cautious
when
repairing
a
tire
that
may
havebeen
inflated
using
in
the
machinery,
severe
injury
could
result
.



an
aerosol
tire
inflator
.
Keep
sparks,
open
flame
or
other
sources

"
Do
not
attempt
to
work
onyourcar
if
you
do
not
feel
well
.
You



of
ignition
away
from
the
tire
repair
area
.
Inflate
and
deflate
the
tire

increase
the
danger
of
injury
toyourself
and
others
if
you
are
tired,



at
least
four
times
before
breaking
the
bead
from
therim
.
Com-

upset
or
have
takenmedication
or
any
other
substance
that
may



Pletely
remove
the
tire
from
the
rim
beforeattempting
any
repair
.

keep
you
from
being
fully
alert
.

"
Illuminate
your
work
areaadequately
but
safety
.
Use
a
portable

safety
light
for
working
inside
or
under
thecar
.
Make
surethe
bulb

is
enclosedbya
wire
cage
.
The
hot
filament
of
an
accidentally
bro-

ken
bulb
can
ignite
spilled
fuel
or
oil
.

"
Catch
draining
fuel,
oil,
orbrake
fluid
in
suitable
containers
.
Do

not
use
food
or
beverage
containers
that
mightmislead
someone

into
drínking
from
them
.
Store
flammable
fluids
away
from
fire
haz-

ards
.
Wipe
up
spills
at
once,
but
do
not
store
the
oily
rags,
which

can
ignite
and
burn
spontaneously
.

"
Always
observe
good
workshop
practices
.
Wear
goggles
when

youoperate
machine
tools
or
work
with
battery
acid
.
Gloves
or

other
protectioeclothing
should
be
worn
whenever
thejob
requires

working
with
harmful
substances
.

"
Greases,
lubricants
and
other
automotive
chemicals
contain

toxic
substances,
many
of
which
are
absorbed
directly
through
the

skin
.
Read
the
manufacturer's
instructions
and
warnings
carefully
.

Use
hand
andeye
protection
.
Avoid
direct
skin
contact

"
Cars
covered
by
this
manual
are
equipped
with
a
supplemental

restraint
system
(SRS),
that
automatically
deploys
an
airbag(s)
in

theevent
of
a
frontal
ímpact
.
The
airbag(s)
is
inflated
byan
explo-

sive
device
.
Handled
improperly
or
without
adequate
safeguards,

can
be
accidently
activated
and
cause
serious
injury
.

"
The
ignition
system
produces
high
voltages
that
can
be
fatal
.

Avoid
contact
with
exposed
terminals
and
use
extreme
care
when

working
ona
car
with
the
engine
running
or
the
ígnition
switched
on
.

"
Place
jack
stands
only
at
locations
specified
bymanufacturer
.

The
vehicle
lifting
jacksupplied
with
the
vehicle
is
intended
for
tire

changes
only
.
A
heavy
duty
floor
jack
shouldbe
used
to
lift
vehicle

before
installing
jack
stands
.
See
010
Fundamentals
for
theDo-
.

it-Yourself
Owner
.

"
Battery
acid
(electrolyte)
can
cause
severeburns
.
Flush
contact

area
with
water,
seek
medical
attention
.

"
Aerosolcleaners
and
solvents
may
contain
hazardous
ordeadly
vapors
and
are
highly
flammable
.
Use
only
in
a
wellventilated

area
.
Do
not
use
on
hot
surfaces
(engines,
brakes,
etc
.)
.

"
Disconnect
the
battery
negative
(-)
terminal
(Ground
strap)



"
Do
not
remove
coolant
reservoir
or
radiator
cap
with
theengine

whenever
you
work
on
the
fuel
system
orthe
electrical
system
.
Do



hot
.
Danger
of
bums
and
engine
damage
.

not
smoke
or
work
near
heaters
or
other
fire
hazards
.
Keep
an

approved
fire
extinguisher
handy
.



continued
on
next
page
vii

Please
read
these
warnings
and
cautions

before
proceeding
with
maintenance
and
repair
work
.

CAUTION-

"
See
also
Warnings
onpage
vi¡



"
Beforedoing
any
electrical
welding
on
cars
equipped
with
ABS,
disconnect
the
battery
negative
(-)
terminal
(ground
strap)
and
the
"
If
you
lack
the
skills,
tools
and
equipment,
ora
suitable
work-



ABS
control
unit
connector
.
shop
for
any
procedure
described
in
this
manual,
we
suggest
you
leave
such
repairs
to
an
authorized
BMW
dealer
or
other
qualified



"
On
cars
equipped
with
anti-theft
radios,
make
sureyou
know
the
shop
.



correct
radio
activation
code
before
disconnecting
the
battery
or
removing
the
radio
.
lf
the
wrong
code
is
entered
into
the
radio
"
BMW
is
constantly
improving
its
cars
and
sometimes
these



when
power
is
restored,
that
radio
may
lock
up
and
be
renderedchanges,
both
in
parts
and
specifications,
are
made
applicable
to



inoperable,
even
if
the
correct
code
is
thenentered
.
earlier
models
.
Therefore,
part
numbers
listed
in
this
manual
are
for
reference
only
.
Always
check
with
your
authorized
BMW
dealer



"
Always
make
sure
ignition
is
off
before
disconnecting
battery
.
parts
department
for
the
latest
information
.
"
Label
battery
cablesbefore
disconnecting
.
Onsome
models,
"
Before
starting
a
job,
make
certain
that
you
have
all
the
neces-



battery
cablesarenot
color
coded
.
sary
tools
and
parts
on
hand
.
Read
al¡
the
instructions
thoroughly,
do
not
attempt
shortcuts
.
Use
tools
appropriate
to
the
work
and



"
Disconnecting
the
battery
may
erase
fault
code(s)
stored
in
con-

use
only
replacement
parts
meeting
BMW
specifications
.
Make-



trol
module
memory
Using
special
BMW
diagnostíc
equipment,
shift
tools,
parts
and
procedures
will
not
make
good
repairs
.



check
forfault
codes
prior
to
disconnecting
the
battery
cables
.If
the
Check
Engine
light
is
illuminated,
see100
Engine-General
for
"
Use
pneumatic
and
electric
tools
only
to
loosenthreaded
parts



On-Board
Diagnostics
(OBD)
fault
code
information
.
lf
any
other
and
fasteners
.
Never
use
these
tools
to
tighten
fasteners,
espe-



system
faults
have
been
detected
(indicated
by
an
ílluminated
cially
on
light
alloy
parts
.
Always
use
a
torque
wrench
to
tighten



warning
light),
see
an
authorized
BMW
dealer
.
fasteners
to
the
tightening
torque
specification
listed
.
"
If
a
normal
or
rapid
charger
is
used
to
charge
battery,
the
battery
"Be
mindful
of
the
environment
and
ecology
.
Before
you
drain
the



mustbe
disconnected
and
removed
fromthe
vehicle
in
order
to
crankcase,
find
outthe
proper
way
to
dispose
of
the
oil
.
Do
not



avoid
damaging
paint
and
upholstery
pour
oil
onto
the
ground,
down
a
drain,
or
into
a
stream,
pond
orlake
.
Dispose
of
in
accordance
withFederal,
State
and
Local
laws
.



"Do
not
quick-chargethe
battery
(for
boost
starting)
for
longer
than
one
minute
.
Wait
at
least
one
minute
before
boosting
the
bat-
e
If
battery
power
is
lost
or
the
battery
has
been
disconnected,
the



tery
a
second
time
.
powerwindows
must
be
re-initialized
.
Both
one
touch
up/down
and
pinch-protection
will
be
inactive
until
windows
are
re-initial-



"
Connect
and
disconnect
a
battery
charger
only
with
the
battery
ized
.
See
512
Door
Windows
.



charger
switched
off
.

"
The
control
module
for
the
anti-lock
brake
system
(ABS)
cannot
withstand
temperatures
from
a
paint-drying
booth
or
aheat
lamp
in
excess
of
203°F
(95°C)
and
should
not
be
subjected
to
temper-
atures
in
excess
of
185°F
(85°C)
for
more
than
twohours
.

"
Sealed
or
"maintenance
free"
batteries
shouldbeslow-charged
only,
at
anamperage
ratethat
is
approximately
10%
of
the
bat-
tery's
ampere-hour
(Ah)
rating
.

"
Do
not
allow
battery
chargingvoltage
to
exceed
16
.5
volts
.
If
the
battery
begins
producing
gas
or
boiling
violently,
reduce
the
charg-
ing
rate
.
Boosting
a
sulfated
battery
at
a
high
charging
rate
can
cause
an
explosion
.

010-12



FUNDAMENTALSFOR
THE
DO-IT
YOURSELF
OWNER

Jump
Starting
Car

Cars
with
discharged
or
dead
batteries
can
be
jump-started
using
the
good
battery
from
another
car
.
When
jump-starting

the
engine,
always
note
the
following
warnings
.

WARNING
-

"
Battery
acid
(electrolyte)
can
cause
severe
burns,
and
will
damage
the
car
and
clothing
.
lf
electrolyte
is
spilled,
wash
the
surface
with
large
quantities
of
water
.
lfit
gets
finto
eyes,
flush
them
with
water
for
severa¡
minutes
and
cal¡
a
doctor
.

"
Batteries
produce
explosive
and
noxious
gas-
ses
.
Keep
sparks
and
flames
away
.
Do
not
smoke
near
batteries
.

"
Do
not
jump-start
the
engine
if
you
suspect
that
the
battery
is
frozen
.
Trapped
gas
may
explode
.
Allow
the
battery
to
thaw
first
.

"
Do
not
quick-charge
the
battery
(for
boost
start-
ing)for
longer
than
one
minute,
and
donot
ex-
ceed
15
volts
at
the
battery
with
the
boosting
cables
attached
.
Wait
at
least
one
minutebefore
boosting
the
battery
a
second
time
.

"
Some
electrical
system
'comfort"
features
may
not
function
correctly
once
battery
power
is
restored
.
For
example,
the
front
window
one-touch-up
func-
tion
may
be
disabled
.
Some
electrical
systems
will
need
to
be
reinitialized
Consult
the
appropriate
re-
pairgroup
formore
specific
information
.

1
.
Place
cars
close
together,
but
do
not
allow
them
to'touch
each
other
.
Turn
off
the
engine
of
thecar
with
the
good
battery
.

2
.
Connect
oneend
of
the
positive
(+)
cable
to
the
positive
(+)
post
of
the
good
battery
.
Remove
the
coverfromthe

positive
(B+)
junction
post
in
the
engine
compartment
of
the
dead
car
and
connect
the
other
end
of
the
posi-
tive
(+)
cable
to
the
junction
post
.
See
Fig
.
17
.

EMERGENCIES

3
.
Connect
one
end
of
the
negative
(-)
cable
to
the
nega-

tive
(-)
battery
post
of
the
good
battery
.
Connect
oppo-

site
end
of
the
negative
cable
(-)
to
the
engine
block
of

thecar
with
the
dead
battery
.

4
.
Start
thecar
with
the
good
battery
and
runthe
engine

at
about2,000
rpm,
then
start
the
car
with
the
dead
bat-
tery
.

5
.
With
the
engine
at
¡dle,
switch
on
the
headlights,
blower

motor
and
rear
window
defogger
to
avoid
damaging
the

cars
electrical
system
.
Carefully
disconnect
the
jumper

cables,
starting
with
the
negative
cable
on
the
engine

block
.
Turn
all
electrical
consumers
off
.

NOTE-

The
engineshould
be
run
for
at
least
an
hour
to
re-
charge
the
battery
.

Overheating

lf
the
temperature
gauge
needle
goes
into
the
red
band
on
the
gauge
face,
the
coolant
temperature
is
too
high
.
Find
a
safe
place
to
stop
and
turn
the
engine
off
.
Open
the
hood
and
allow

the
engine
to
cool
until
the
temperature
gauge
needle
is
at
the

lower
thirdof
the
scale
.
Continuing
to
drive
an
overheated
car

can
cause
extensive
engine
damage
.

WARNING
-

Do
not
remove
the
coolant
reservoir
or
radíator
cap
with
the
engine
hot
.
Undoing
either
couldspray
hot
coolant
and
cause
burns
or
damage
the
engine
.

CAUTION-

Do
not
add
cold
water
or
coolant
to
a
hot
engine
.
Engine
damage
could
result
from
the
sudden
tem-
perature
change
.

NOTE-

If
the
enginecannot
be
safely
tumed
off,
make
sure
the
air
condifioner
isoff
and
turn
the
heater
to
high
.
This
will
helo
cool
the
engine
until
a
salestopping
place
canbe
reached
.

Overheating
may
be
caused
bylow
coolant
leve¡
or
a
dam-aged
engine
drive
belt
.
Visually
check
the
coolant
leve¡
and
en-
gine
belts
as
described
in
020
Maintenance
Program
.
lf
the
coolant
leve¡
is
low,
check
the
filler
cap,hoses,
clamps
and
ra-
diator
for
signs
of
leakage
.
Check
for
leaks
at
the
water
pump
on
the
frontof
theengine
.

lf
no
leaks
are
found,
add
coolant
after
the
engine
has
cooled
.
The
carcan
be
driven,
but
have
the
cooling
system
thoroughly
checked
assoonas
possible
.
lf
replacement
cool
0013245



-



ant
is
not
available,
then
plain
water
canbe
used,
butthe
cool-
antshould
later
be
drained
and
refilled
with
theproper
mixture
Fig
.
17
.
Battery
jump
starting
posts
(arrows)
behind
right
frontstrut



of
anti-freeze
and
water
.
tower
.
Lift
cover
to
access
positive
post
.

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

100-
1
2
ENGINE-GENERAL

NOTE-

The
oxygen
sensor
signal
is
ignored
until
the
engine
reachesa
specified
minimum
temperature
.
Therefore,



The
primary
input
usedby
the
fuel
injection
system
to
deter-

when
troubleshooting
cold
engine
driveability
prob-



mine
how
much
fuel
should
be
delivered
is
the
signal
from
the

lems,
the
oxygensensor
canbe
ruled
out
asa
possible



mass
air
flow
sensor
in
the
intake
air
ductwork
.

cause
.

As
the
oxygen
sensor
ages,
its
ability
to
react
quickly
to

changing
conditions
deteriorates,
and
it
may
eventually
cease

to
produce
any
signal
at
all
.
To
check
the
operation
of
the
oxy-

gen
sensor,
see
130
Fuel
Injection
:

NOTE-

On
1996
and
latercars,
OBD
11
enhanced
emission
standards
require
the
engine
control
module
(ECM)
to
monitor
the
oxygen
content
in
the
exhaust
both
before
and
after
the
catalytic
converter
.
Thisallows
for
tighter
control
of
the
tail
pipe
emissions
and
also
allowsthe
ECM
to
diagnose
converter
problems
.
If
the
DME
de-
tects
that
catalytic
converter
or
oxygensensor
efficien-
cyhas
degraded
pasta
certain
pre-programmed
limit,
it
will
turn
on
the
Check
Engine
light,
and
store
a
diag-
nostic
trouble
code
(DTC)
in
the
ECM
.

DRIVEABILITY
TROUBLESHOOTING

Catalytic

B9506

Air
Flow
Measurement
and
Vacuum
Leaks

Because
proper
fuel
metering
depends
on
accurate
mea-

surement
of
the
incoming
air,
any
unmeasured
air
that
enters

the
engine
downstream
of
the
mass
air
flow
sensor
will
cause

a
lean
air-fuel
mixture
and
possibly
affectdriveability
.

NOTE-

Fig
.
10
.
Regulating
oxygen
sensor
measures
oxygen
content
of
ex-



gattery
Voltage
hausY
gas
as
indicator
of
.¡_fi
.1
ratio
and
"-k,
.

E-
effi-
ciency
.
Monitoríng
oxygen
sensor
(not
shown)
monitors

If
a
large
air
leak
is
causing
driveability
problems,
the
Check
Engine
light
will
usually
be
illuminated
and
a
fault
will
be
stored
in
the
fault
code
memory
.
See
On
Board
Diagnostics
(OBD)
.

There
are
many
places
for
unmeasured
air
to
enter
theen-

gine
.
First,
inspect
all
hoses,
fittings,
ducts,
seals,
and
gaskets

in
the
intake
air
tract
for
cracks
or
looseness
.
It
may
be
neces-

sary
to
remove
parts
that
cannot
be
fully
checked
in
their
in-

stalled
positions
.
Also
make
sure
all
of
the
intake
manifold
and

throttle
body
mounting
nuts
are
tight
.

In
addition
to
air
leaks,
air
restrictions
can
also
cause
drive-

ability
problems
.
Remove
the
air
filter
and
hold
it
up
to
a
strong

light
source
.
If
the
filter
does
not
pass
light,
it
is
restricted
and

should
be
replaced
.
Also,
remove
the
intake
air
ductwork
and

check
for
oily
deposits
at
the
throttle
plate
.
Buildup
in
this
area

can
cause
an
erratic
idle
.
Clean
away
any
deposits
using
a

cloth
wetted
withcarburetor
cleaner
and
reinstall
the
ductwork
.

CAUTION-

Do
not
spray
carburetor
cleaner
directly
in
the
throt-
tle
anea
.
Spraying
cleaner
may
force
it
into
the
throt-
tle
position
switch
or
sensor
and
cause
damage
.

catalytic
converter
operation
.



All
of
the
electrical
components
in
the
fuelinjection
and
igni-
tion
systems
require
a
minimum
voltage
to
operate
properly
.

When
troubleshooting
engine
driveability
problems,
one
of
Replacement
of
oxygensensors
at
the
specified
intenrals
en-



the
first
checks
should
be
to
make
sure
the
battery
is
fully
sures
that
the
engine
and
emission
control
system
wili
continue



charged
and
capable
of
delivering
allits
power
to
the
electricalto
operate
as
designed
.
As
the
oxygen
sensor
ages,
its
ability
to



system
.
react
quickly
to
changing
conditions
deteriorates,
and
it
may
eventually
cease
to
produceany
signal
at
all
.



To
make
a
quick
check
of
battery
charge,
measure
the
volt-
age
across
the
battery
terminals
with
all
cables
attached
and
As
the
oxygen
sensor
ages,
its
ability
to
react
quickly
to



the
ignition
off
.
A
fully
charged
battery
will
measure
12
.6
volts
changing
conditions
deteriorates,
and
it
may
eventually
cease



or
slightly
more,
compared
to
12
.15
volts
for
a
battery
with
a
to
produce
any
signal
at
all
.
To
check
theoperation
of
the
oxy-



25%
charge
.
gen
sensor,
see130
Fuel
Injection
.

Even
a
fully
charged
battery
cannot
deliver
power
unless
it

is
properly
connected
to
the
electrical
system
.
Check
the
bat-
tery
terminals
for
corrosion
and
loosecableconnections
.
If
the
battery
does
not
maintain
the
proper
voltage,
the
charging
system
may
be
atfault
.
See
121
Battery,
Starter,
Alternator
.

113-4



CYLINDER
HEAD
REMOVAL
AND
INSTALLATION

20
.
Disconnect
main
engine
wiring
harness
connector
.
La-

bel
and
disconnect
harness
connectors
for
crankshaft

and
camshaft
sensors
.
See
Fig
.
8
.

0012504

Fig
..
Crankcase
vent
valve
(A),
camshaft
and
crankshaft
sensor
harness
connectors
(B),
locating
bushings
(C),
main
engine
wiring
harnessconnector
(D)
.
M44
engine
shown
.

NOTE-

Early
engines
do
not
havea
maín
disconnect
at
the
lower
intake
manifold
harness
.
lf
necessary,
remove
the
cable
ducting
bolts
and
set
harness
ducting
aside
.

21
.
Remové
lower
section
of
intake
manifold
.

"
Remove
Y
shaped
supportbracket
from
underside
of
manifold
.
(See
Fig
.
6
.)
"
Unbolt
support
brackets
from
alternator
and
starter
.
"
Remove
nuts
holding
manifold
to
cylinder
head
and
pull
manifold
back
until
harness
connectors
for
oil

pressure
switch
and
coolant
temperature
sensorare

accessible
.
Label
and
disconnect
connectors,
then
re-

move
manifold
and
set
aside
.

Timing
chains,
uncoupling



26
.
Lock
crankshaft
in
TDC
position
by
insertíng
BMW
spe-

22
.
On
M42
engines,
remove
thermostat
housing
from
up-



cial
tool
no
.
11
2
300
through
bore
and
into
hole
infly-

per
timing
chaincover
.



wheel
or
driveplate
.
See
Fig
.
11
.

23
.
On
late
M44
engines
(January
1997
and
later),
remove



NOTE-
secondary
air
injection
check-valve
from
front
of
engine



"
If
necessary,
remove
plug
from
locating
bore
in
lower
and
lay
aside
.



edge
of
bell
housing
to
insert
locking
tool
.

24
.
Remove
cylinder
identification
sensor
from
upper
tim-
ing
chaincover
.
Remove
upper
timing
chaincover
.
See
Fig
.
9
.

25
.
Set
engine
to
approximate
TDC
by
rotating
in
normal
operating
direction
until
camshaft
lobes
at
cylinder
no
.
1
are
facing
each
other
.
See
Fig
.
10
.

CYLINDER
HEAD,
4-CYLINDER

Fig
.
9
.



Upper
timing
chain
cover
bolts
(arrows)
.
Remove
secondary
air
injection
check
valve
fromhose
(A)
on
M44
engine
.
Re-
move
cylinder
identification
sensor
from
chaincover
(B)
.

0011998

Fig
.
10
.
Engine
set
to
approximate
TDC
.
Cylinder
no
.
1
camshaft
lobes
face
in
and
arrows
on
sprockets
poínt
up
(arrows)
.

"
Confirm
that
the
locking
tool
has
been
correctly
in-
stalled
by
trying
to
rotate
the
crankshaft
.

27
.
Lock
camshafts
at
TDC
by
mounting
BMW
specíal
tool
no
.
113
240
over
square
ends
of
camshafts
.
See
Fig
.
12
.

NOTE-

Check
that
tool
is
squarely
seated
on
cylinder
head
gasket
surface
.
If
necessary,
rotate
camshafts
slightly
using
an
open-end
wrench
at
hex
oncamshafts
.

Fig
.
23
.
When
reinstalling
chain
tensioner
on
M44
engine,
old
oil
in
tensioner
piston
mustbe
expelled
bycompressing
piston
in
vise
.
When
compressing
piston,
only
compress
up
to
end
cir-
clip
(arrow)
.

21
.
Turn
engine
overby
hand
in
direction
of
rotation
at
least

two
fui¡
rotations
.
Reinstall
camshaft
and
crankshaft

locking
tools
to
check
engíne
timing
.
Remove
locking

tools
if
no
faults
are
found
.

22
.
Insta¡¡
upper
timingchain
cover
.

"
Install
gaskets
and
instan
cover
using
two
mounting



Tightening
Torque

bolts
.
Using
a
screwdriver,
lever
down
on
front
cover



"
Cylinder
head
cover
until
cover
gasket
surface
is
flush
with
cylinder
head



to
cylinder
head
(M6
screws)
.......
10
Nm
(89
in-lb)

gasket
surface
.
See
Fig
.
24
.
Tighten
two
bolis
.

"
Insta¡¡
and
tighten
remainder
of
bolis
.

23
.
Install
cylinder
head
cover
.

CYLINDER
HEAD
REMOVAL
AND
INSTALLATION



113-
9

0012507

Fig
.
24
.
Install
upper
timing
case
cover
with
two
bolis,
then
press

down
on
cover
so
that
top
surface
is
flush
withcylinder
head
(arrow)
.
Hold
cover
in
position
and
tighten
bolis
.

"
Clean
old
gasket
glue
from
sealing
surfaces
.
Usea

small
amount
of
3-Bond
®
1209
adhesive
or
equivalent

at
corners
of
half-moon
cut-outs
at
back
of
cylinder

head
.
See
Fig
.
25
.

NOTE-

OnM44
engines,
reptace
sea¡
for
oil
supply
tube
.
See
Fig
.
17
.)

Fig
.
25
.
Rear
of
cylinder
head
cover
showing
area
where
sealant
(ar-
rows)
should
be
applied
.
Inset
shows
cylinder
head
cover
mounting
bolt
and
insulator
assembly
:
M6
screw
(1),
rubber
damper
(2),
washer
(3)
.

24
.
Installation
of
remaining
parts
is
reverseofremoval,

noting
the
following
:

"
Make
sure
al¡
sealing
surfaces
are
clean
and
free
of
old

gasket
material
.
Install
new
intake
manifold
gasket
.

"
On
M44
engine
:
Replace
seals
above
and
below

crankcase
ventvalve
.

"
When
installing
lower
intake
manifold,
make
sure
hol-

low
locating
bushings
are
on
two
lower
studs
.

"
Reinstall
harness
connectors
for
oil
pressure
switch

and
coolant
temperature
sensor
before
installing
in-

take
manifold
.
Tighten
manifold
nuts
in
stages
.

"
Refill
cooling
system
as
described
in
170
Radiator

and
Cooling
System
.

"
Change
engine
oil
and
filter
as
described
in
020
Main-

tenance
Program
.

"
If
necessary,
adjust
accelerator
cable
.

"
Run
engine
at
approx
.
3,500
rpm
for
about
20
seconds

to
allow
hydraulic
chain
tensioner
to
fill
with
oil
.

"
Reconnect
battery
last
.

CYLINDER
HEAD,-CYLINDER