1993 BMW 325i Iat

010-14



FUNDAMENTALS
FOR
THE
DO-ITYOURSELF
OWNER

Fig
.
19
.
Instaf
rear
tow
lug
into
threaded
hole
.

if
absolutely
necessary,
cars
with
automatic
transmissions
can
be
towed
with
the
rear
wheels
on
the
ground,
butthe
tow

should
not
exceed
25
miles
(40
km),at
speeds
at
or
below30
mph
(35
km/h)
.
Be
sure
the
transmission
fluid
hasbeen
topped

off
before
starting
the
tow
.
Always
tow
thecar
with
the
transmis-

sion
lever
in
"N"
(neutral)
.
If
the
tow
must
exceed25
miles
(40

km),
add
one
quart
of
ATF
to
the
transmission,
or
better
yet,
re-

move
the
driveshaft
.
Be
sure
to
drain
or
pump
outthe
added
flu-
id
once
the
tow
has
been
completed
.

NOTE-

"
ATF
draining
and
filling
is
covered
in
240
Automatic
Transmission
.

"
Driveshaft
removal
is
covered
in
260
Driveshaft
.

EMERGENCIES

úo1W¿b

Spare
Parts
Kit

Carrying
a
basic
set
of
spare
parts
can
prevent
a
minor

breakdown
from
turning
into
a
major
annoyance
.
Many
of
the

following
itemswon't
allow
you
todo
major
repair
workon
the

car,
but
they
will
help
in
the
event
of
the
failure
of
something
that

can
disable
thecar
or
compromise
its
safety
.

Spare
Parts
Kit
-
Basic
Contents

"
Drive
belt
(V-belt
or
poly-ribbed)

"
Engine
oil
(one
or
two
quarts)

"
Engine
coolant
(1
gallonof
premixed
50/50
anti-freeze

and
water)

"
Fuse
assortment
(7
.5A,
10A,
15A,
20A)

"
Radiator
hoses
(upper
and
lower)

Spare
Parts
Kit
-
Additional
Contents

"
Exterior
lighting
bulbs
(headlight,
brakelight,
turn
signal,

and
taillight)

"
Wiper
biades

"
Brake
fluid
(new
unopened
bottle,
DOT
4
specification)

"
Main
relay
for
DME
system

020-2



MAINTENANCE
PROGRAM

GENERAL

The
information
given
in
this
repair
group
includes
the
routine

checks
and
maintenance
steps
that
are
both
required
by
BMW

under
the
terms
of
the
vehicle
warranty
protection
and
recom-

mended
by
BMW
to
ensure
long
and
reliable
vehicle
operation
.

GENERAL

NOTE-

Aside
from
keeping
yourcar
in
the
bestpossible
condi-
tion,
proper
maintenance
plays
a
role
in
maintaining
full
protection
under
BMWs
new-car
warranty
coverage
.
If
in
doubtabout
the
terms
and
conditions
of
yourcark
warranty,
an
authorized
BMW
dealer
should
be
able
to
explain
them
.

NOTE-

BMW
is
constantly
updating
their
recommended
main-
tenance
procedures
and
requirements
.
The
informa-
tion
contained
here
is
as
accurate
as
possible
at
the
time
of
publication
.
If
hhere
is
any
doubt
aboutwhat
pro-
cedures
apply
to
a
specific
model
or
model
year,
or
what
intervals
should
be
followed,
remember
that
an
authorized
BMW
dealer
has
the
latest
information
on
factory-recommended
maintenance
.

BMW
Service
Indicator

The
BMW
Service
Indicator
notifies
the
driver
when
mainte-
nance
is
required
.
The
service
indicator
consístsof
multiple
light
emitting
diodes
(lEDs)-typically
five
green,
one
yellow,
andone
red-as
well
as
OIL
SERVICE
and
INSPECTION
indi-
cators
.

When
the
ignition
is
tumed
on,the
green
LEDs
come
on
.
They
go
out
when
the
engine
is
started
.
After
the
Service
Indi-
cator
is
reset,
al¡
green
LEDs
will
be
illuminatedwith
the
keyon
.
As
thecar
is
driven
in
normal
use,
fewer
and
fewer
green
LEDs
will
be
illuminated
before
start-up,indicating
that
the
next
main-
tenance
interval
is
approaching
.

When
thecar
has
accumulated
sufficient
use
to
require
the
next
maintenance
interval,
the
yellow
LED
will
come
on
along
with
either
the
OIL
SERVICE
indicator
or
the
INSPECTION
in-
dicator
.
These
LEDs
will
stay
on
after
the
engine
is
started
.
If
maintenance
service
is
delayed,
thered
LED
will
also
illuminate
as
a
reminder
that
maintenance
service
is
overdue
.

An
OIL
SERVICE
interval
will
alwaysbe
followed
by
an
IN-
SPECTION
interval,
which
will
then
be
followed
byan
OIL
SER-VICE
interval,
andsoon
.
See
Fig
.
1
.

'
80
100/

60
II

"
1

,



ló
1
,
4
`20
140s



#
X120
100
leo
A
O
,



80



km/h`F



*101
200
,
,
~60

BMW
has
taken
a
unique
approach
to
establishing
mainte-

nance
intervals
.
BMW's
Service
Indicator
System
computes

maintenance
intervais
based
not
only
on
elapsed
mileage,
but



Fig
.
1
.



Service
indicator
display
in
lower
section
of
speedometer
.
also
on
such
inputs
as
enginespeed,engine
temperature,
number
of
starts,
and
length
oftrips
.
At
the
appropriate
time,
the
system
indicates,
through
lights
in
the
instrument
cluster,
when



Oil
Service

the
next
routine
maintenance
is
due
.

The
Oil
Service
indicator
signals
the
need
for
the
most
basic
levelof
routine
maintenance
.
BMW's
required
oil
service
speci-
fies
changing
the
engine
lubricating
oil
and
the
engine
oil
filter

after
the
engine
has
been
warmed
up
.
BMW-recommended
ad-

ditional
maintenance
for
this
service
is
listed
in
Table
a
.

NOTE-

For
reference,
the
BMW
Oil
Service
requirements
are
approximately
equivalent
to
the
maintenance
that
other
European
manufacturers
specify
at
intervals
with
a
maximum
of
every
7,500
miles
or6
months
.

CAUTION-

Be
sure
to
follow
the
ínstructions
forresetting
the
Oil
Service
indicator
fight
.
The
Inspection
indica-
tor
can
be
accidentally
reset
rendering
its
function
inaccurate
.

Inspection
l
and
Inspection
II

The
Inspection
indicator
signals
the
need
for
more
compre-
hensive
maintenance
and
Inspection
.
There
are
two
sets
of
in-
spection
requirements,
Inspection
I
and
Inspection
ll
.
These
inspections
alternate
throughout
a
car's
maintenance
history
.
If
the
last
Inspection
interval
was
Inspection
I,
the
next
Inspection
interval
(following
an
Oil
Service)
will
be
Inspection
ll,
the
next
after
that
will
be
Inspection
I,
and
so
on
.

Inspection
I
tasks
are
listed
in
Table
b
.
Inspection
II
in-
cludes
most
of
the
tasks
from
Inspection
I
with
additional
In-
spection
11
tasks
.
A
complete
listing
of
Inspection
II
tasks
are
listed
in
Table
c
.

020-
1
0



MAINTENANCE
PROGRAM

1.
Run
engine
for
afewminutes
to
warm
engine
oil
.
Shut



5
.
When
oil
flow
has
diminished
to
an
occasional
drip,
re-

engine
off
.



install
drain
plugwith
a
new
metal
sealing
washerand

torque
plug
.

2
.
With
car
on
level
ground,
place
drain
pan
under
oil
drain

plug
.
See
Fig
.
5
.



Tightening
Torques

"
Engine
oil
drain
plug

M12
bolt
(17mm
wrench)
.
...
.
..
.
25
Nm
(18
ft-Ib)



-

M22
bolt
(19mm
.
wrench)
...
.
...
.
60
Nm
(44
ft-Ib)

Fig
.
5
.



Engine
oil
drain
plug(arrow)
in
oil
pan
.

3
.
Remove
filter
housingcover
.
Remove
filter
cartridge

and
discard
any
O-rings
.
See
Fig
.
6
.

CAUTION-

Pulí
the
loose
plug
away
from
the
hole
quickly
to
avoidbeing
bumed
by
hot
oil
.
It
wíll
runout
quickly
when
the
plug
ís
removed
.
If
possible,
use
gloves
to
protect
your
hands
.

ENGINE
COMPARTMENT
MAINTENANCE

0012460

Fig
.
6
.



Engine
oil
filter
cartridge
.
Note
O-ring
locations
when
removing
cover
and
filter
.

4
.
Using
a
socket
or
box
wrench,
loosen
drain
plug
at
oil

drain
pan
.
By
hand,
remove
plug
and
letoil
drain
into

pan
.

6
.
Lubricate
and
install
new
O-rings
.
Install
a
new
filter

cartridge
and
housingcover
.
Tighten
cover
.
See
Fig
.
7
.

7



«
a~
.~~
fT~

iII~IIIi~
.

Fig
.
7
.



Oil
flter
housing
on
6-cylínder
engine
.
4-cylinder
engine
is

similar
.

Tightening
Torque

"
Engine
oil
filter
cover
to
oil

filter
housing
...................
25
Nm
(18
ft-Ib)

7
.
Refill
crankcase
with
oil
.'Approximate
oil
capacity
is
list-

ed
in
Tablee
.
Use
dipstick
to
check
correct
oil
level
.

8
.
Start
engine
and
check
that
oil
pressure
warning
light

immediately
goes
out
.

9
.
Allow
engine
to
run
for
a
few
minutes
to
círculate
new

oil,
then
check
for
leaks
at
drain
plug
and
oil
filter
.
Stop

engine
and
reclieck
oil
level
.

ENGINE
COMPAR



ENT
MAINTENANCE

The
information
underthis
heading
describes
routine
mainte-

nance-other
than
oil
change-done
in
the
engine
compart-

ment
.
It
is
not
necessary
for
the
car
to
be
raised
and
supported
off
the
ground
.
Information
on
oil
change
is
given
earlier
under

Engine
Oil
Change
.

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
.

Accelerator
and
Throttle
Linkage

The
accelerator
and
throttie
linkage
should
be
lubricated
pe-
riodically
.
Use
a
general
purpose
oil
on
the
joints
and
bearings

of
the
linkage
.
Use
a
multipurpose
grease
on
the
bearing
points

of
the
throttie
plate
.

Engine
Drive
Belts

Drive
belts
and
pulleys
transfer
power
from
theengine
crank-

shaft
to
various
accessories
.
See
Fig
.
13
.
Depending
on
model

and
model
year,
engine
driven
accessories
are
driven
by
V-

belts,
poly-ribbed
(serpentine)
belts,
or
a
combination
of
the

two
.
For
example,
early
4-cylinder
engines,
usetwo
V-belts
and
one
poly-ribbed
belt
.

Inspect
drivebelts
with
the
engine
off
.
lf
the
belt
shows
signs

of
wear,
cracking,
glazing,
or
missing
sections,
it
should
be
re-

placed
immediately
.

V
belt,
replacing

(4-cylinder
engines
built
up
to
1194)

0012472

Fig
.
13
.
Drive
belt
and
tensioner
assembly
for
late
4-cylinder
engine
wíth
poly-ribbed
drive
belt
.

V-belts
should
be
inspected
during
regular
maintenance
in-

tervais
.
Incorrect
tension
can
decrease
the
life
of
the
belt
and

the
component
it
drives
.
The
V-belt
tension
is
adjusted
through

a
toothed-rack
mechanism
.

Inspect
belts
with
the
engine
off
.
Twist
the
beltto
inspect
its

sidewalls
and
bottom
.
Beltstructural
damage,
glazed
or
shiny

sidewaljs
caused
by
a
loose
belt,
orseparation
are
al¡
reasons

to
replace
a
belt
.

Replacement
of
the
V-belts
every
four
years
is
recommend-

ed
.
Loosen
the
mounting
bolts
and
adjust
the
belt-driven
unit

until
the
belt
tension
is
as
loose
aspossible
.
Remove
the
belt
by

slipping
it
over
the
pulleys
.
In
some
cases
it
may
be
necessary

to
removeone
V-belt
to
get
to
another
.
Use
a
torque
wrench
and

a
crowfoot
wrench
to
turn
the
tensioning
gear
bolt
and
set
belt

tension
.
Hold
the
wrench
steady
and
tighten
the
locknut
on
the

rear
of
the
tensioning
gear
bolt
.
Tighten
al¡
other
mounting
nuts
.

MAINTENANCE
PROGRAM



020-
1
3

NOTE-

"
For
the
most
accurate
check,
V-belt
tension
should
be
checked
using
a
V-belt
tension
gauge
.

"
Belt
squealing
is
normally
caused
by
loose
beltten-sion
.
Belt
dressings
should
not
be
used
.

Tightening
Torques

"
Tensioning
gear
(alternator

belt
tensioning)
.
.
.
...............
7
Nm
(62
in-lb)

"
Tensioning
gear(power
steering

belt
tensioning)
...
..
...
8
to
8
.5
Nm
(71
to
75
in-lb)

"
Tensioning
gear
locking
nut
.......
24
Nm
(18
ft-Ib)

NOTE-

When
belts
are
replaced
with
new
ones,
store
the
old
set
in
the
luggage
compartment
for
emergency
use
.

When
installing
a
new
belt,
gently
pry
it
over
the
pulleys
.
Too

much
force
may
damage
the
belt
or
the
accessory
.
Tension
the

belt(s),
runthe
engine
for
a
few
minutes
(at
least
1500
rpm),

then
recheck
the
belt
tension
.

CAUTION-

Do
not
over
tighten
the
V-belts
.
Overtightening
will
cause
shaft
bearings
to
fail
prematurely
.

Poly-ribbed
belt,
replacing

(4-cylinder
engines
buiit
from
1194

and
all
6-cylinder
engines)

An
automatic
belt
tensioner
is
used
to
keep
the
belts
ten-

sioned
properly
.
Unless
the
tensioner
mechanism
malfunc-

tions,
the
poly-ribbed
belts
do
not
require
tension
adjustment
.

To
reduce
the
chance
ofbelt
failure
while
driving,
replace-

ment
of
the
belts
every
four
years
is
recommended
.
Mark
drive

belt
rotationdirectíon
if
removing
and
reusing
an
old
belt
.

To
remove
the
belt,
it
is
necessary
toretract
the
self-tension-

er
.
Using
a
breaker
bar
or
other
long
socket
assembly,
rotate

the
tensioner
to
loosenthe
belt
.
See
Fig
.
14
or
Fig
.
15
.
On
4-cyl-

inder
engines,
it
will
benecessary
to
remove
the
A/C
compres-

sor
belt
to
remove
the
main
drive
belt
.

WARNING
-

Observe
care
when
replacing
the
belt
.
Personal
in-
jury
could
result
if
the
tensioner
springs
back
into
position
uncontrollably
.

With
the
belt
removed
from
the
pulleys,
inspect
the
pulleys

for
wear
or
damage
that
may
cause
early
failureof
the
new
belt
.

This
is
also
a
good
opportunity
to
inspect
the
belt-driven
acces-

sories,
checking
for
bearing
wear
and
excess
play
.
Drive
belt

routing
is
shown
in
Fig
.
16
and
Fig
.
17
.

ENGINE
COMPARTMENT
MAINTENANCE

NOTE-

Use
a14
mm
or17
mm
alíen
bit
socket
to
remove
the
drain
plug
.

"
If
thecar
is
raised
in
the
air,
it
shouldbe
leve¡
.

Fuel
tank
and
fuel
fines,
inspecting

0012474

Inspect
the
fuel
tank,
fuel
lines,
and
fuel
system
for
damage

or
leaks
.
Check
for
fuel
leaks
in
the
engine
compartment
or

fuel
odors
in
the
passenger
compartment
.
Check
for
faultyfuel

lines
bybending
them
.
If
any
leaks
are
present,
fuel
should
be

expelled
.
Check
for
any
evaporative
emissions
hoses
that

may
have
become
disconnected,
checking
carefully
at
the

charcoal
canister
and
evaporative
emissionspurge
system
.

See130
Fuel
Injection
and
160
Fuel
Tank
and
Fuel
Pump

for
component
locations
and
additional
information
.

WARNING
-

When
checking
for
fuel
leaks,
the
engine
must
be
cold
.
A
hot
exhaust
manifold
or
exhaust
system
could
cause
the
fuel
to
ignite
or
explode
causing
se-
rious
personal
injury
.
Uentilate
the
workarea
and
clean
up
spilled
fuel
immediately
.

Clutch
fluid,
checking

The
hydraulic
clutch
and
the
brake
system
share
the
same

reservoir
and
the
same
brake
fluid
.
Clutch
fluid
leve¡
and
brake

fluid
level
are
checked
at
the
same
time
.
See340
Brakes
for

more
information
.
See210
Clutch
for
information
on
the
clutch

and
the
hydraulic
clutch
operating
system
.

MAINTENANCE
PROGRAM



020-19

Drive
axie
joint
boots,
inspecting

100
Engine-General

The
protective
boots
must
be
closely
inspected
for
cracks
andany
other
damage
that
will
allow
contaminants
to
get
ínto
the
joint
.
If
the
rubber
boots
faf
,
the
water
and
dirt
that
enter
the
joint
will
quickly
damage
¡t
.
Replacement
of
the
drive
axle
joint
boots
and
inspection
of
the
joints
are
described
in
330
Rear
Suspension
.

BODY
AND
INTERIOR
MAINTENANCE

Windshield
Wiper
Biade
Maintenance

Common
problems
with
the
windshield
wipers
include

streaking
or
sheeting,
water
drops
after
wiping,
and
blade
chat-

ter
.
Streaking
is
usually
caused
when
wiper
blades
are
coated

with
road
film
or
car
wash
wax
.
Clean
the
blades
using
soapy
water
.
If
cleaning
theblades
does
not
cure
the
problem
then

they
should
be
replaced
.
BMW
recommends
replacing
the
wip-
er
blades
twice
a
year,
before
and
after
the
cold
season
.
Onold-

er
cars,
check
the
tension
spring
that
holds
the
wiper
to
the

glass
.
Replace
the
wiper
arm
if
the
springs
are
weak
.

Drops
that
remainbehind
after
wipingare
caused
by
oil,
road

film,
or
diesel
exhaust
coating
the
windshield
.
Use
an
alcohol
or

ammonia
solution,
or
a
non-abrasive
cleanser
to
clean
the

windshield
.

Wiper
blade
chatter
may
be
caused
by
dirty
or
worn
blades,

bya
dirty
windshield,
or
by
bentor
twisted
wiper
arms
.
Clean

the
blades
and
windshield
as
described
above
.
Adjust
the
wiper

arm
so
that
there
is
even
pressure
along
the
blade,
and
so
that

the
blade
is
perpendicular
to
the
windshield
atrest
.
Lubricate

the
wiper
linkage
with
a
light
oil
.
The
linkage
is
located
under

the
hood
on
the
drivers
side
.
If
the
problem
persists,
theblades
are
excessively
aged
or
worn
and
should
be
replaced
.
See
611
Wipers
and
Washers
.

Body
and
hinges,
lubricating

The
door
locks
and
lock
cylinders
canbe
lubricated
with
an

oil
that
contains
graphite
.

The
body
and
door
hinges,
the
hood
latch,
and
the
door

check
rods
should
be
lubricated
with
SAE
30
or
SAE
40
engine

oil
.
Lubricate
the
seat
runners
with
multipurpose
grease
.
Do
not

apply
any
oil
to
rubber
parts
.
If
door
weatherstrips
are
sticking,

lubricate
them
with
silicone
spray
or
talcum
powder
.
The
hood

release
cable
should
be
lubricated
as
well
.

The
use
of
winter
lock
de-icer
spraysshould
be
kept
to
an
ab-

solute
minimum,
as
the
alcohol
in
the
de-icer
will
wash
the

grease
out
of
the
lock
assemblies,
and
may
cause
the
locks
to

corrode
internally,
or
become
difficult
to
operate
.

ENGINE-GENERAL
100-1

100-2
ENGINE-GENERAL

Cylinder
Head
and
Valvetrain

The
aluminum
cylinder
head
uses
chain-driven
double
overhead
camshafts
and
four
valves
per
cylinder
.
See
Fig
.
1
.

The
cylinder
head
employs
a
crossflow
design
for
greater

power
and
efficiency
.
Intake
air
enters
the
combustion
cham-

ber
from
one
side
while
exhaust
gasses
exit
from
the
other
.

Oílways
in
the
head
provide
lubrication
for
the
camshafts)
and
valvetrain
.

Fig
.
1
.



M52
twin-cam,
4-valve-per-cylinder
engine
with
hydraulíc
lift-
ers
.

On
all
engines
exceptthe
M44
engine,
valveclearance
is
by
seif-adjusting
hydraulic
lifters
.
On
M44
engines,
instead
of
hy-

draulic
lifters,
hydraulic
pedestaisare
used
in
combination
with
roller
rocker
arms
to
actuate
the
valves
.
Hydraulic
pedes-
tals
have
the
same
function
as
hydraulic
lifters,
which
ís
to
maintain
zero
valve
clearance,
reduce
valve
noise,
and
elimí-
nate
routíne
adjustment
.
See
Fig
.
2
.

VANOS
(Variable
Valve
Timing)

GENERAL

1
.
Camshafts
2
.
Rocker
arms
3
.
Hydraulic
valve
adjusters
(HVA)
4
.
Valve
and
conical
valve
spring

4

Fig
.
2
.



Cross
sectionof
M44
twin-cam,
4-valve-per-cylinder
head
.
Note
function
of
hydraulíc
pedestal
in
combination
with
rock-er
arm
(with
roller
bearing
for
reduced
friction)
.

The
main
components
of
the
VANOS
system
arethe
piston

housing
with
integral
spool
valve
and
solenoid,
and
the
modi-

fied
intake
camshaft
and
sprocket
assembly
.
See
Fig
.
3
.

1993
and
later
6-cylinder
engines
are
equipped
with
a
vari-



B11001

able
intake
valve
timing
system,
known
as
VANOS
(from
the
German
words
Variable
Nockenwellen
Steuerung)
.
The



Fig
.
3
.
VANOS
(variable
intake
valve
timing)
systemusedon
M52
en-
VANOS
system
electro-hydraulically
adjusts
intake
valve
tim-



gine
.
When
solenoid
is
actuated,
oíl
pressure
is
directed
to
ingfor
enhanced
mid-range
performance
.
The
VANOS
sys-



front
side
of
gear
cup
piston
.
This
forces
gear
cup
finto
camtem
is
controlled
by
the
engine
control
module
(ECM),
using



shaft
to
advance
intake
valve
timing
.
enginespeed,engine
load
and
engine
temperature
asthe
pri-
mary
inputs
.



When
the
engine
is
running,
the
piston
housing
is
supplied
with
pressurized
engine
oil
víathe
solenoid-actuatedspool
At
low
speeds,
the
intake
valves
open
late
to
ensure
smooth



valve
.
Depending
on
the
position
of
the
spool
valve,
oil
isdi
engine
operation
.
At
mid-rangespeeds,
thevalves
open
early



rected
to
either
the
front
or
back
side
of
the
gear
cup
piston
.
(valvetiming
advanced,
VANOS
actuated)
for
increased
torque,
improved
driveability,
and
reduced
emissions
.
And
at



When
the
solenoid
isin
the
off
position,
engine
oíl
is
direct-
high
speeds,
the
valves
again
open
late
for
optimum
power



ed
to
the
back
side
of
the
piston
.
This
holds
the
gear
cup
for-
and
performance
.



ward
and
valve
timing
is
maintained
at
the
normal
"late"
position
.
When
the
solenoid
is
energized,
the
spoolvalve
is
moved
forward
and
oil
pressure
is
directed
to
the
front
side
of
the
piston
.
This
in
turn
moves
thegear
cup
further
into
the

camshaft
secondary
drive,
causing
thecamshaft
to
"advance"

12
.5°
.
The
helical
gears
are
cut
so
that
forward
motion
of
the

gear
cup
is
transiated
into
rotational
motion
of
the
camshaft
.

See
117
Camshaft
Timing
Chain
for
testing
and
repair
infor-
mation
on
the
VANOS
system
.

DISA
(Dual
Resonance
Intake
System)

DISA,usedon
4-cylinder
engines,
is
a
dual
intake
runner

system
that
effectively
provides
the
advantages
of
both
short

and
long
intake
runners
within
the
same
engine
.
For
best
per-

formance,
long
intake
runners
aremost
beneficial
atlow-
and
mid-engine
speeds
(below
4,200
rpm),
and
short
intake
run-
ners
enhance
torque
at
high
engine
speeds
(above4,200
rpm)
.

NOTE-

The
term
DISA
comes
from
the
German
words
Differ-
enzierte
Sauganlage,
and
can
roughty
be
transiated
as
a
differing
intake
manifold
configuration
.

The
DISA
solenoid
valve
is
controlled
by
the
DME
control

module,
using
engine
speed
as
the
primary
input
.
The
main

components
of
the
system
are
the
modified
twin-section
in-

takemanifoldwith
change-over
valve,
the
twin-barrel
throttle

body,
and
the
electrical/pneumatic
actuating
components
.

See
Fig
.
4
.

r

I

I

I

?
,
in
UpPer,
take
-1
manifold

1
-1
Throttle
housing
(Heated)

q
:lZU

Fig
.
4
.



DISA
system
components
.
DISA
changes
the
intake
runner

length
based
on
engine
speed
.

The
DISA
system
electro-pneumatically
changes
the
intake
runner
length
through
the
twin-section
intake
manifold
and
a
change-over
butterfly
valve
.
The
change-over
valve
is
located
at
a
point
in
the
intake
manifold
where
four
pipes
come
into
two
.
When
the
change-over
valve
is
closed,
the
4-way
primary
intake
manifold
and
the
2-way
ram
air
manifold
areconnected
to
make
the
"long"
configuration
.
When
the
change-overvalve
opens,
intake
air
flow
is
redirected
through
only
the
short
4-

way
primary
intake
manifold
.

The
change-over
valve
is
held
in
the
normally
open
position
bya
spring
.
Thisallows
for
an
open
valve
in
the
event
of
sys-
tem
failure
.
During
low
andmid
enginespeeds,
the
DME
con-

trol
module
supplies
power
to
the
solenoid
valve,
which
in
turn

allows
vacuum
to
be
applied
lo
the
vacuum
diaphragm
.
This

causes
the
valve
to
close
(long-pipe
configuration)
.
When
en-
gine
speed
reaches
approximately
4,800
rpm,
the
DME
con-
trol
module
electrically
signals
the
solenoid
valve
and
the
valve
opens,
creating
the
short
pipe
configuration
:

Further
detafs
on
DISA
canbefound
in
130
Fuel
Injection
.

Engine
Management
System

Al¡
enginescoveredby
this
manual
usean
advanced
engine

management
system
called
Digital
Motor
Electronics
(DME)
.

In
the
DME
system,
advancedOn-Board
Diagnostics
(OBD),

fuel
injection,
ignition,
and
otherfunctions,
are
combined
under

the
control
of
theEngine
Control
Module
(ECM)
.
See
Fig
.
5
.

-



Lower
intake
manifold

DISAvacuum
'
~servo

EíY1z

ENGINE-GENERAL
100-
3

le

-
DISA
solenoid
valve

0012591

/
with
butterfly
va¡

GENERAL