1998 BMW M3 check engine

NOTE-

The
vibration
damper
center
bolt
is
very
tight
.
A
heavy
duty
holding
device,
such
as
BMW
special
tool
no
.
112
150,
should
be
used
to
hold
the
vibration
damper
hub



V
stationary
while
the
bolt
is
loosened
.
v

11
.
Usingloosened
bolt
at
vibration
damper,
turn
crank-

shaft
to
TDC
and
lock
in
position
by
inserting
BMW

special
tool
no
.
11
2
300
through
transmission
bell-



-



p

housing
.
See
Fig
.
5
.



v

O

NOTE-



I\



0011966a

"
If
necessary,
remove
plugfrom
locating
boye
in
lower
edge
of
bell
housing
.

"
Confirm
that
locatng
tool
has
been
correctlyinstalled
by
trying
to
rotate
the
crankshaft
.

Fig
.
7
.



Lower
timing
chain
cover
mounting
bolts
(arrows)
.
Bolts
A

Fig
.
5
.



BMW
special
tool
no
.
11
2300
installed
through
bellhousing



are
installed
through
hollow
locating
dowels
.

and
finto
flywheel
to
lock
crankshaft
at
TDC
(arrow)
.

CA
UTION-

Thecamshafts
mustbe
locked
in
the
MC
position
using
the
specialservice
tool
before
removing
the
timing
chain
.
The
tool
holds
the
camshafts
parallel

to
each
other
and
perpendicular
to
the
valve
cover
gasket
surface
.

12
.
Lockcamshafts
at
TDC
bymounting
BMW
special
tool

no
.
113
240
over
square
ends
of
camshafts
.
See
Fig
.
6
.

"
Check
that
tool
is
squarely
seated
on
cylinder
head

gasket
surface
.
If
necessary,
rotate
camshafts
slightly

using
an
open-end
wrench
at
hexon
camshafts
.

13
.
Remove
lower
timing
chaincover
mounting
bolts
and

carefully
lift
cover
off
.
Clean
sealing
surfaces
and
gas-

ket
grooves
.
See
Fig
.
7
.

14
.
Remove
hydraulic
chaintensioner
from
right
side
of
cyl-

inder
head
.
See
Fig
.
8
.

CAMSHAFT
TIMING
CHAIN



117-
3

Fig
.
6
.



BMW
special
tool
no
.
11
3240
installed
on
rearof
camshafts
to
position
camshafts
at
TDC
.
(M44
camshafts
shown
.
Other
engines
are
similar
.

Fig
.
8
.



Hydraulic
chain
tensionerplug
(arrow)
.

CAMSHAFT
TIMING
CHAIN,
4-CYLINDER

M42
Engine

CL
(EM

Fig
.
11
.
Two
versionsof
hydraulic
chaintensioners
.
Original
chain
ten-
sioner
on
M42
engine
(top)
canbe
disassembled
.
Chain
ten-
sioner
on
M44
engine
(bottom)
cannot
be
disassembled
.
Note
differences
in
outer
sleeve
.
Also,
the
M42
tensioner
de-
tent
ring
groove
is
visible
when
tensioner
is
extended
(arrow)
.

Outer
sleeve
Spring

0013024a

Detent

ring

9
.
On
M44
engines
:
Clamp
tensioner
piston
in
vice
(soft

jaws)
and
squeeze
oil
from
it
.
Slowly
compress
piston

only
up
to
end
círclip
.
Repeat
procedure
twice
to
ensure

al¡oil
is
expelled
.
See
Fig
.
13
.

10
.
Insta¡¡
hydraulic
chain
tensioner
lo
cylinder
head
.
Usea
new
sealing
washer
on
tensionerplug
when
installing
.

Tightening
Torque

"
Chain
tensioner
to
cylinder
head
....
40
Nm
(30
ft-Ib)

11
.
On
M42
engines
:
Release
early-style
chain
tensioner
by
pressing
chain
guide
against
tensioner
until
it
un-

locks
and
expands
out
.

CAMSHAFT
TIMING
CHAIN



117-
5

0012507

Fig
.
13
.
When
reinstalling
chain
tensiones,
oil
in
tensioner
piston
must

first
be
expelled
by
compressing
piston
in
vise
.
When
com-
pressing
piston,
only
compress
up
to
and
circlip
(arrow)
.

Tightening
Torque

"
Chain
sprocket
lo
camshaft
flange
(M6)
..
.
..
.............
.
..
10
Nm
(89
in-lb)

13
.
Remove
crankshaft
locking
tool
from
bellhousing
and

camshaft
locking
tool
from
rear
of
cylinder
head
.

14
.
Install
lower
timingchain
cover
:

"
Insta¡¡
new
crankshaft
oil
seal
in
cover
.

"
Use
new
gaskets
when
installing
cover
.

"
Thoroughly
clean
profile
gasketgroove
and
all
gasket

sealing
surfaces
on
lowerchaincover
.

"
Apply
a
small
bead
of
silicon
sealer
(3-Bond
1209
or
Snap



equivalent)
lo
joint
corners
where
chaincover
meets

ring



0013024



head
and
block
.
See
Fig
.
14
.

"
Tap
cover
into
position
to
engage
locating
dowels
.

Fig
.
12
.
Disassembled
early-style
chain
tensioner
usadon
M42
en-



"
Tighten
cover
mounting
bolts
alternately
and
in
stages
.

gine
.

12
.
Check
that
chain
is
now
free
of
siack
.
Tighten
down

sprocket
mounting
bolts
.



where
chain
cover
meets
head
and
block
(arrows)
.
Fig
.
14
.
Apply
sealer
(3-Bond
1209
0
or
equivalent)
to
joint
corners

CAMSHAFT
TIMING
CHAIN,
4-CYLINDER

117-
6



CAMSHAFT
TIMING
CHAIN

15
.
Insta¡¡
upper
timing
chaincover
:



17
.
Remove
crankshaft
locking
tool
from
transmission
bell-

"
Thoroughly
clean
profile
gasketgroove
and
all
sealing



housing
and
camshaft
locking
tool
from
rear
of
cylinder

surfaces
.



head
.

"
Applya
small
bead
ofsilicon
sealer
(3-Bond
1209®
or

equivalent)
to
upper
and
lower
joint
comers
where



18
.
Turn
engine
over
by
hand
in
direction
of
rotation
at
least

chaincover
meets
cylinder
head
.



two
full
rotations
.
Reinstall
camshaft
and
crankshaft

"
Insta¡¡
new
profile
gasket
to
groove
in
lowerchain
cover
.



locking
tools
to
check
engine
timing
.
Repeat
cam
timing

"
Protect
top
of
profile
gasket
using
thin
sheetmetal



procedure
if
tools
do
not
fit
easily
into
position
.
Remove

(BMW
special
tool
no
.
11
2
330
or
equivalent)
.
See



locking
tools
.

Fig
.
15
.
"
Attach
new
gaskets
to
cover
with
light
dabs
of
gasket



19
.
Install
cylinder
head
cover
as
described
in
113
Cylin-

sealant,
hold
gaskets
in
placeusing
cover
mounting



der
HeadRemoval
and
Installation
.

screws
.

"
Place
upper
timing
cover
into
position
.
Snug
down
al¡



NOTE-
screws,
without
tightening
.
Carefully
slide
out
sheet



OnM44
engines,
note
oil
supply
O-ring
and
replace
ff
metal
.



necessary
.
"
Temporarily
install
cylinder
head
cover
without
gasket
.

Insta¡¡
and
tighten
at
least
two
cylinder
head
cover
mounting
bolts
to
seat
upper
timing
chaincover
.
"
Tighten
all
upper
timing
cover
screws
.



Tightening
Torque

"
Remove
valve
cover
.



"
Cylinder
head
cover

to
cylinder
head
(M6
screws)
...
..
.
.
10
Nm
(89
ín-Ib)

-



CAMSHAFT
TIMING
CHAINS,
Fig
.
15
.
When
installing
upper
timing
chain
cover,
use
thin
sheetmetal



6-CYLINDER
(arrow)
to
protect
profile
gasket
when
installing
uppercover
.

Tightening
Torque

"
Upper
timing
chaincover
to
engine
block
or
cylinder
head
(M6
screws)
....
.
..
10
Nm
(89
in-lb)

16
.
Install
vibration
damper
while
aligning
woodruff
key
.
Hold
crankshaft
stationary
and
tighten
mounting
bolt
.

Tightening
Torques



I
CAUTION-

"
Pulley
to
vibration
damper
..
.
.
.
....
22
Nm
(17
ft-Ib)



lf
the
camshaftsare
not
properly
timed,
the
1
pis-
tons
can
contact
thevalves
.
"
Vibration
damper
tocrankshaft
M16
stretch
bolt
(always
replace)
.
330
Nm
(244
ft-Ib)

CAMSHAFT
TIMINGCHAINS,
6-CYLINDER

20
.
Installation
of
remaining
parts
is
reverse
of
removal
.
When
installing
thermostat,
make
sure
arrow
or
vent
hole
faces
up
.
Refill
cooling
system
as
described
in
170
Radiator
and
Cooling
System
.

Tighteníng
Torques

"
Coolant
drain
plug
to
cylinder
block
.
..
.
.
.
...
.
..
.....
25
Nm
(18
ft-Ib)

"
Radiator
cooling
fan

to
coolant
pump
.
..
.
...
...
..
.....
40
Nm
(30
ft-Ib)

"
Radiator
drain
screw
to
radiator
....
2
.5
Nm
(22
in-lb)

Camshaft
timing
chainremovalon
6-cylinder
engines
re-
quires
that
you
Rmove
the
engine
oil
pan
by
raising
the
en-
gine
and/or
lowering
the
front
suspension
crossmember
.

Special
BMW
service
tools
are
needed
for
timing
chain
re-
moval
and
installation
procedures
.
The
special
tools
assure
proper
timing
of
the
valvetrain
.
Precise
marks
to
setthe
timing
on
the
camshafts
arenot
provided
for
reassembly
.
Read
the
procedures
through
before
beginning
thejob
.

Camshaft
timing
chains,
removing

(6-cylinder
engines)

1
.
Disconnect
negative
(-)
cable
from
battery
.

CA
UTION-

Disconnecting
the
battery
may
erase
fault
codes)
stored
in
control
module
memory
.
Check
for
fault
codes
using
special
BMW
diagnostic
equipment
.

2
.
Drain
engine
coolant
.
Drain
engine
block
by
removing

block
drain
.
Remove
radiator
cooling
fan
shroud
and

cooling
fan
.
See170
Radiator
and
Cooling
System
.
.

WARNING
-

Allow
the
engine
to
cool
before
openingor
draining
the
system
.

CAUTION-

Radiator
fan
has
left
hand
threads
.

NOTE-

The
block
drain
plug
is
located
on
the
exhaust
side
of
the
engine,
below
cylinder
no
.
4
.

3
.
Drain
engine
oíl
andremove
oil
pan
.
See
119
Lubrica-

tion
System
.

4
.
Remove
alternator
cooling
duct
.

5
.
Remove
two
large
coolant
hoses
from
thermostat

housing
.
Remove
engine
lifting
bracket
and
thermostat

housing
from
front
of
cylinder
head
.

6
.
Loosen
bolts
for
coolant
pump
pulley
.
Then
remove

drive
belts
for
alternator
andA/C
compressor
.
See
020

Maintenance
Program
.
Remove
coolant
pump
pulley
.

Fig
.
16
.

NOTE-

OnM50
engines
with
a
two-roller
drive
belt
tensioner,

remove
the
upper
rollerto
access
thetensioner
mount-
ing
bolts
.

NOTE-

Make
note
of
the
arrangement
of
the
rubber
insulators

when
removing
the
cylinder
head
cover
mounting
bolts
.

CAMSHAFT
TIMING
CHAIN



117-
7

Fig
.
16
.
Drive
belt
tensioner
mounting
bolts
(arrows)
.

B11055

7
.
Remove
drive
belt
tensioner
from
front
of
engine
.
See



Fig
.
17
.
1992-1995
M50
engine
speed
sensor
on
timing
cover
(ar-
row)
.

10
.
Unclip
andremove
baffle
cover
from
above
intake
cam-

shaft
.
See
Fig
.
18
.

11
.
On
1992
engines
:
Remove
upper
timing
chain
cover

from
front
of
cylinder
head
.
See
Fig
.
19
.

8
.
Remove
engine
speed
sensor
from
lower
timing
chain



12
.
Loosen
spark
plugs
.
See
120
Ignition
System
.

cover,
if
applicable
.
See
Fig
.
17
.

13
.
Set
engine
to
approximate
TDC
by
rotating
in
normal

9
.
Remove
cylinder
head
cover
.
See
113
Cylinder
Head



operating
direction
until
camshaft
lobes
at
cylinder
no
.

Removal
and
Installatíon
.



1
are
facing
each
other
.
See
Fig
.
20
.

14
.
Set
engine
to
TDC
by
aligning
"0/T'
mark
(0°TDC)on

front
vibration
damper
with
cast
bosson
lower
timing

chain
cover
.
See
Fig
.
21
.

15
.
Remove
vibration
damper
mounting
bolts
and
remove

vibration
damper
and
pulley
.
See
Fig
.
22
.

CAMSHAFT
TIMING
CHAINS,
6-CYLINDER

Fig
.
22
.
Vibration
damper
with
drive
belt
pulley
being
removed
.
Notehub
locating
dowel
(arrow)
.

Fig
.
23
.
BMW
special
tool
no
.
11
2
300
installed
through
bellhousing
and
into
flywheel
.

20
.
Remove
primary
chain
tensioner
plug
and
primary

chain
tensioner
.
See
Fig
.
25
.

CAMSHAFT
TIMING
CHAIN



117-
9

Fig
.
24
.
BMW
special
tool
no
.
113
240
installed
on
rear
of
camshafts
to
position
camshafts
at
TDC
.
(M44
camshafts
shown
.
Other
engines
are
similar
.)

Fig
.
25
.
Primary
chain
tensioner
plug
(arrow)
.

CAUTION-

"
Check
thattool
is
squarely
seated
on
cytinder
head
gasket
surface
.
If
necessary,
rotate
cam-
shafts
slightly
using
a
24
mm
wrench

"
On
pre-VANOS
engines
(engines
built
up
to
8-
92),
the
camshaft
locking
tool
may
not
fit
correct-
ly
when
the
crankshaft
is
set
to
TDC
.
Do
notas-
sume
the
valve
train
is
out
oftime
.
On
some
engines,
valve
overlap
may
havebeen
reduced

as
a
dealer
service
campaign
to
correct
for
an

uneven
idle
.
Check
thetiming
by
placing
a
3mm
drill
bit
under
the
left
and
right
outside
edges
while
pressíng
down
on
thecenter
of
the
tool
(tool
center
bolts
loosened)
.
If
the
tool
now
fits,

the
campaign
has
beendone
on
the
engine
.

CAMSHAFT
TIMING
CHAINS,
6-CYLINDER

117-
1
2



CAMSHAFT
TIMING
CHAIN

4
.
Mount
primary
timing
chain
sprocket
to
primary
chain

so
that
arrowon
sprocket
faces
up
.
Mount
sprocket
to

camshaftso
that
tapped
holes
in
camshaftare
on
left

side
of
elongated
holes
in
sprocket
.
See
Fig
.
31
.

NOTE-

On
engines
built
beginning
from
March
1995,
the
VANOS
intake
cam
sprocket
assembly
was
updated
to
ínclude
a
spring
plate
and
two
thrust
washers
.
See
Fig
.

Fig
.
31
.
Primary
timing
chain
sprocket
correctly
alignedto
exhaust



33
.
camshaft
.
Elongated
sprocket
holes
should
be
aligned
to
left
side
of
threaded
camshaft
holes
.

5
.
On
1993
and
later
engines
:Install
BMW
special
tool
no
.
11-3
390
into
primary
timíng
chain
tensionersleeve
.
Thread
toolin
finger
tight
until
slack
is
removed
from

chain
.

"
Check
that
elongatedholes
in
primary
sprocket
are

centered
to
bolt
holes
in
camshaft
and
chain
is
free
of
slack
.

NOTE-

BMW
special
tool
no
.
11
3
390
ís
a
dummy
primary
chaín
tensioner
and
simulatesthe
function
of
the
hy-
draulic
tensíoner
.

7
.
Install
cylinder
identification
trigger
píate
to
front
of
in-

take
camshaft
.
On
1993
and
later
engines,
instanthrust
washer
tofrontof
intake
camshaft
.

CAMSHAFT
TIMING
CHAINS,
6-CYLINDER

B11136

Fig
.
32
.
Secondary
chain
sprockets
being
installed
.
Attach
sprockets
with
arrows
pointing
up
and
elongated
holes
centered
to
threaded
holes
in
shaft
flange
.

6
.
Install
primary
timing
chainguide
and
secondary
chain
tensioner
.
Tighten
mounting
bolts
.
(Tensioner
remains



Fig
.
33
.
VANOS
spring
plate
and
thrust
washers
on
engines
built
3/95locked
down
for
now
.)



and
later
.

10
.
On
1993
and
later
cars,
tighten
nuts
at
intake
camshaft
sprocket
.

8
.
Insta¡¡
secondary
chainsprockets
and
chain
asan
as-
sembly
so
that
arrows
on
sprockets
are
pointing
up
.



Tightening
Torque
(1996
and
later)

Centermounting
holes
in
sprockets
tobolt
holes
in



"
Intake
camshaft
sprocket
nut
camshafts
.
See
Fig
.
32
.



to
stud
(M6)
.............
.10t
1
Nm
(89
±9
in-lb)

9
.
On
1993
and
later
engines
:
Insta¡¡
thrust
washers
and
spring
plate
(where
applicable)
to
intake
cam
sprocket
.



11
.
On
1992
engines
:
Insta¡¡
primary
chain
tensioner
so
that
cutout
in
tensioner
piston
engages
chain
rail
.
See
Fig
.
34
.
Check
that
chain
is
free
of
slack
.

Fig
.
34
.
Primary
timíng
chain
tensioner
being
instafed
.
Pistoncutout
mustbe
in
position
shown
to
engage
chain
rail
.

12
.
On
1993
and
later
engines
:
Install
VANOS
control
unit

as
described
later
in
this
repair
group
.

13
.
Unlock
and
release
secondary
chaintensioner
.



NOTE-

On
pre-VANOS
engines,
be
sure
toinstall
the
3mm
drill
bits
on
left
and
right
sides
of
tool
.
14
.
On
1992
engines
:
Tighten
intake
and
exhaust
timing
chain
sprocket
bolts
alternately
in
two
stages,
working
at
intake
side
first
.

Tightening
Torques

"
Secondary
timing
chaira
sprockets
to
camshafts

(M7
Torx
bolts)

Stage
1
....
.
.
.
...
...............
5
Nm
(44
in-lb)
Stage
2
..
.
.
.
.
.
.
................
22
Nm
(17
ft-Ib)

15
.
On
1992
engines
:
Install
upper
timing
chaincover
to
cylinder
head
using
a
new
gasket
.
Apply
a
small

amount
ofliquid
gasket
sealer
(3-Bond
1209
®
orequiv-

alent)
around
coveralignment
dowels
.

16
.
On
1993
and
later
engines
:
Preloadprimary
chain
by
tightening
BMW
special
tool
no
.
11
3
390
(dummy



21
.
Install
cylinder
head
cover
mounting
studs
.
Insta¡¡
oil
chain
tensioner)
to
1
.3
Nm
(11
in-lb)
.
Then
tighten
ex-



baffle
cover
.
Install
cylinder
head
cover
.
haust
camshaft
sprocket
bolts
alternately
in
twostages
.

Tightening
Torques
(1993
and
later
engines)

"
Exhaust
camshaft
sprockets
to
camshafts

(M7
Torx
bolts)

Stage
1
..
...
..
..
................
5
Nm
(44
in-lb)

Stage
2
.....
.
.
...
..............
22
Nm
(17
ft-Ib)

17
.
Remove
flywheel
locking
tool
from
transmission
bell-

housing
.
Remove
camshaft
locking
tool
from
rear
of

cylinder
head
.

CAMSHAFT'TIMING
CHAIN



117-
1
3

18
.
Insta¡¡
crankshaft
hubandwasher
while
aligning
woo-
druff
key
.
Hold
hub
stationary
and
tighten
mounting
bolt
.
Install
vibration
damper
and
pulley,
making
sure
that
lo-
cating
pin
in
hub
engages
hole
in
vibration
damper
.

NOTE-

When
installing
crankshaft
hub
mounting
bolt,
the
stepped
(shouldered)
sideof
the
washer
should
fase
the
hub
.

Tightening
Torques

Crankshaft
hub
to
crankshaft
(stretch
bolt-
always
replace)
........
410
±
20
Nm
(300
±
15
ft-1b)

"
Vibration
damper
and
pulley

to
crankshaft
hub
(M8)
...
..
.
..
....
22
Nm
(17
ft-Ib)

19
.
Turn
engine
over
by
hand
in
direction
of
rotation
atleast
two
full
rotations
.
Reinstall
camshaft
and
crankshaft
locking
tools
to
check
engine
timing
.
Remove
locking
tools
if
no
faults
are
found
.

20
.
On
1993
and
later
engines
:
Remove
BMW
special
tool11
3
390
(dummy
tensioner)
.
Install
primary
chain
ten-sioner
so
that
cutout
in
tensioner
piston
engages
the
chain
rail
.
See
Fig
.
34
.
Install
and
tighten
access
plugs

in
VANOS
control
unit
.

Tightening
Torques

"
Access
plugs

to
VANOS
control
unit
..........
.
..
50
Nm
(37
ft-Ib)

"
Primary
timing
chain
tensioner
to
tensioner
sleeve

M50/S50US
engine
.......
.
..
..
.
.
50
Nm
(37
ft-Ib)

M52/S52US
engine
..........
..
.
.
40
Nm
(30
ft-Ib)

Tightening
Torque

"
Cylinder
head
cover

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

CAMSHAFT
TIMINGCHAINS,
6-CYLINDER

117-
1
4



CAMSHAFT
TIMING
CHAIN

22
.
Installation
of
remaining
parts
is
reverse
of
removal,



When
theengine
is
running,
the
piston
housing
is
supplied

noting
the
following
:



with
pressurized
engine
oil
.
At
idie,
the
solenoid
isin
the
off

"
When
installing
thermostat,
make
sure
arrow
or
vent



position
(de-energized)
and
valve
timing
is
maintained
in
the

hole
faces
up,
if
applicable
.



normal
position
:
When
the
solenoid
is
energized,
the
gear
cup

"
Refill
cooling
systemas
described
in
170
Radiator



piston
moves
forward
to
advance
the
camshaftby
a
maximum

and
Coming
System
.



of
12
.5
.

"
Install
oil
pan
as
described
in
119
Lubrication
Sys-

tem
.
"
Fill
engine
with
oil
and
install
a
new
oil
filter
as
de-

scribed
in
020
Maintenance
Program
.

"
Insta¡¡
ground
wires
at
cylinder
head
cover
mounting

studs
and
at
front
of
cylinder
head
and
thermostat

housing,
where
applicable
.



VANOS
system
operation,
testing

Tightening
Torques



There
are3
special
tools
required
to
check
VANOS
opera-

"
Coolant
drain
plugto
cylinder
block
.
.
25
Nm
(18
ft-Ib)



tion
;
an
electricaltest
lead
(BMW
special
tool
no
.
12
6
410),
an

"
Radiator
cooling
fan
to
coolant
pump
.
40
Nm
(30
ft-Ib)



air
line
fitting
(BMW
special
tool
no
.
11
3
450),
and
a
crank-

"
Radiator
drain
screw
to
radiator
...
.
2
.5
Nm
(22
in-Ib)



shaft
TDC
locking
tool
(BMW
special
tool
no
.
112
300)
.

"
Upper
timing
chaincover
to
cylinder
head



The
test
leal
is
used
to
power
the
solenoid,
simulating
the
M6
nut
...
.....
.............
..
.
10
Nm
(89
in-lb)



ground
signal
from
the
DME
control
unit
.
The
air
line
fitting
M8
bolt
.....
....
.
.
.............
22
Nm
(17
ft-Ib)



takes
the
place
of
the
oil
supply
line
fitting
to
simulate
oil
Ares-
"
VANOS
control
unit
to
cylinder
head



sure
.
The
locking
tool
positions
and
locks
the
crankshaft
at

M6
nut
.........
..
..
.
..........
10
Nm
(89
in-lb)



TDC,
cylinder
no
.
l.
M8
bolt
........
...
.............
22
Nm
(17
ft-Ib)

"
VANOS
oil
supply
pipe
to
VANOS
control
unit



1
.
Remove
alternator
cooling
air
duct
.

banjo
bolt
.......
..
..
.
..........
32
Nm
(24
ft-Ib)

VANOS
(VARIABLE
VALVE
TIMING)



3
.
Remove
top
plastic
enginecovers
.
Disconnect
ignition

coil
harness
connectors
fromcofs
.
Remove
ignition

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



coils
.

able
valve
timing
system
called
VANOS
.
This
system
is
con-

trolled
by
the
engine
management
system
and
dynamically



4
.
Remove
cylinder
head
cover
mounting
bolts
and
re-

adjusts
intake
camshaft
timing
based
on
engine
load,
engine



move
cylinder
head
cover
.
Unclip
andremove
oil
baffle

speed
and
engine
temperature
.



cover
from
above
intake
camshaft
.
See
113
Cylinder

Head
Removal
and
installation
.

The
main
components
of
the
VANOS
system
are
the
control

unit
with
piston
housing
and
integral
spool
valve,
and
the
mod-

ified
intake
camshaft
.
See
Fig
.
35
.

VANOS
(VARIABLE
VA
LVE
TIMING)

Fig
.
35
.
VANOS
control
unit
with
modified
intake
camshaft
.

B11001

WARNING
-

Special
BMW
service
tools
are
required
to
check
and
repair
the
VANOS
System
.
Read
theproce-

dures
through
before
beginning
the
job
.

2
.
Disconnect
crankcase
ventilation
hose
fitting
from
cyl-

inder
head
cover
.

NOTE-

Note
the
arrangement
of
the
cylinder
head
cover
bolt
insulators
and
gaskets
during
removal
.

5
.
Set
engine
to
approximate
TDC
by
rotating
in
normal

operating
direction
until
camshaft
lobes
at
cylinder
no
.

1
are
facing
each
other
.
See
Fig
.
20
.

6
.
Set
engine
to
TDC
by
aligning
"0/T"
mark
(0°TDC)on

front
vibration
damper
withcast
boss
on
lower
timing
chain
cover
.
See
Fig
.
21
.

7
.
Lock
crankshaft
in
position
by
inserting
BMW
special

tool
no
.
11
2
300
through
transmission
bellhousing
and

into
hole
in
flywheelor
driveplate
.
See
Fig
.
36
.

NOTE-

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