engine BMW M3 1994 E36 Workshop Manual

Cooling
System
Pressure
Test



If
the
engine
overheats
and
no
other
cooling
system
testsindicate
trouble,
the
radiator
may
have
some
pluggedpassag-

A
cooling
system
pressure
test
is
used
to
check
for
internal



es
that
are
restricting
coolant
flow
.

leaks
.
Some
of
the
common
sources
ofinternal
leaks
are
a
faulty
cylinder
head
gasket,
a
cracked
cylinder
head,
or
a



Temperature
Gauge
Quick
Check
cracked
cylinder
block
.

The
coolant
temperature
sensor
is
located
on
the
intake
To
doa
cooling
system
pressure
test,
a
special
pressure



manifold
(left)
side
of
the
cylinder
head,
under
the
intake
man-
tester
is
needed
.



ifold
runners
.
See
Fig
.
2
.

WARNING
-

At
normal
operating
temperature
-
the
cooling
sys-
tem
is
pressurized
.
Allow
the
system
to
cool
before
opening
.
Release
the
cap
slowly
to
allow
sale
re-
tease
of
pressure
.

With
the
engine
cold,instan
a
pressure
tester
to
the
expan-

sion
tank
.
Pressurize
thesystem
to
the
specification
listed
be-

low
.
Pressure
should
not
drop
more
than
0
.1
bar
(1
.45
psi)
for

at
leakt
two
minutes
.
If
the
pressure
drops
rapidly
and
there
is
no
sign
of
an
externa¡
leak,
the
cylinder
head
gasket
may
be
faulty
.
Considera
compression
test
as
described
in
100
En-

gine-General
.

The
screw-on
type
expansion
tank
cap
should
also
be
test-

ed
using
a
pressure
tester
and
the
correct
adapter
.

Cooling
System
Test
Pressure

"
Radiator
test
pressure
.........
.
1
.5
bar
(21
.75
psi)

"
Radiator
cap
test
pressure
..
.
........
2
bar
(29
psi)

CA
UTION-

Exceeding
the
speclfied
test
pressure
could
dam-
age
the
radiatoror
other
system
components
.

Carefully
inspect
the
radiator
cap
for
damage
.
Replace
a

faulty
cap
or
a
damaged
cap
gasket
.

Thermostat
Quick
Check



In
later
models,
the
ECT
sensor
and
the
gauge
sender
are
combined
into
one
sender
unit
.
For
wire
colors
refer
to
Table
a
.
To
check
if
the
thermostat
is
opening
and
coolant
is
circulat-

ing
through
the
radiator,
allow
a
cold
engine
to
reach
operat-

ing
temperature
(temperature
gauge
needieapproximately

centered)
.
Shut
off
engine
.
Feel
the
top
radiator
hose
.
If
the

hose
is
hot
to
the
touch,
the
coolant
is
probably
circulating
cor-
rectly
.
If
there
are
any
cool
areas
in
the
hose
or
radiator,
cool-

ant
flow
to
the
radiator
is
probably
restricted
.
Check
for
a
faulty

thermostat
or
aplugged
radiator
.

NOTE-

A
thermostat
that
is
stuck
open
will
cause
the
engine
to
warmup
slowly
and
run
belownormal
temperature
at
highway
speed
.
A
thermostat
that
is
stuck
closed
will
re-

strict
coolant
flow
to
the
radiator
and
cause
overheating
.

RADIATOR
AND
COOLING
SYSTEM



170-
3

U
.¡ig
.v

Fig
.
2
.
Temperature
gauge
sender
on
M44
engine
.
Temperature
gauge
sender
location
is
similar
on
al]
engines
.

In
early
models,
the
engine
coolant
temperature
(ECT)
sen-

sor
for
the
fuel
injection
and
the
coolant
temperature
gauge

sender
are
located
side
by
side
.

Table
a
.
Coolant
Temperature
Sensor
Wire
Colors

Function



Sensor



Terminal



Wire
colors
location
number

Two
sensors
:
Temperature
Rear
1
Brown/violet
gauge
sender



2



Brown/yellow
ECT
sensor



Front



1



Brown/red
2



Brown
or
Brown/black

One
sensor
:
Temperature
Dual
1
Brown/yellow
gauge
sender



sensor



2



Brown/violet
ECT
sensor



3



Brown/red
4
Brown/black
or
Grey/black

TROUBLESHOOTING

170-
4



RADIATOR
AND
COOLING
SYSTEM
A
quick
testat
the
coolant
temperature
gauge
sender
can



The
auxiliary
cooling
fan
comes
on
when
coolant
tempera

determine
if
the
gauge
is
functioning
correctly
.



ture
exceeds
a
predetermined
leve¡
or
whenever
the
air
condi-

tioning
is
on
.
A
dual-range
temperature
switch
for
cooling
fan
lf
the
gauge
needie
remains
at
the
rest
position
with
theen-



control
is
mounted
on
the
right
side
of
the
radiator
.
See
Fig
.
3
.
gine
warm,
remove
the
harness
connector
from
the
sender
and
jumper
the
correct
terminals
in
the
connector
to
simulate
a
high
engine
temperature
.
See
Table
a
.
Turn
the
ignition
on
.

If
the
gauge
needle
moves
upward,
the
sender
is
faulty
.
If
the

gauge
does
not
respond,
the
wiring
to
the
gauge
is
broken
(open
circuit)
or
the
gauge
itselfis
faulty
.

WARNING
-

1996
and
laten
models
are
OBD
11
compliant
.
Dis-
connecting
electrical
connectors
wíth
the
ignition
turned
on
may
set
fault
codes
in
the
ECM
.
It
is
rec-
ommended
that
you
leave
the
diagnosis
of
faults
in
the
coolant
temperature
sensorsystem
to
the
BMW
dealer
service
department
which
has
specialized
OBD
11
scan
tool
equipment
.

If
the
gauge
needle
reads
too
high
when
the
engine
is
cold,
remove
the
harness
connector
from
the
sender
.
Turn
the
igni-

tion
on
.
lf
the
gauge
needle
position
does
not
change,
the
wir-

ing
or
the
gauge
is
shorted
to
ground
.
If
the
gauge
needle

drops,
the
sender
is
faulty
and
should
be
replaced
.
When
re-

placing
a
faulty
coolant
temperature
sender,
the
gasket
ring
on
the
sender
should
also
be
replaced
.

Tightening
Torque

"
Temperature
gauge
sender
to
engine
18
Nm
(13
ft-Ib)

Cooling
fan,
testing

NOTE-

OnM44
engines
with
manual
transmission,
the
primary
electric
cooling
fan
is
mounted
on
the
engine
side
of
the
radiator
and
is
controlled
by
the
engine
control
module
(ECM)
.
Troubleshooting
thiscircuit
should
be
left
to
an
authorized
BMW
dealer
with
the
proper
diagnostic
equipment

An
otherwise
sound
cooling
system
may
still
overheat,
par-
ticularly
with
prolonged
idling,
due
to
a
failure
of
the
coolíng

fan(s)
.

The
belt-driven
cooling
fan
is
controlled
by
a
temperature
dependent
viscous
clutch
.
A
failed
fan
clutch
may
affect
air
flow
through
the
radiator
resulting
in
overheating
orpossibly
overcooling
.
Speed

Low
sp
High
s

With
the
engine
off,
check
thefan
clutch
by
spinning
thefan
.



eed
The
fan
should
spin
on
the
clutch
with
some
resistance
.



peed
Check
for
signs
of
leaking
fluid
from
the
clutch
.
If
thefan
free-
wheels
with
no
resistance,
cannot
be
tu
rned
by
hand,
or
there
are
signs
of
oil
leakage,
the
clutch
should
be
replaced
.

TROUBLESHOOTING

Fig
.
3
.



Radiatorcooling
fan
temperature
switch
(arrow)
.

WARNING
-

"
Use
caution
when
testing
the
electric
cooling
fan(s)
and
coolant
temperature
switch
.
Keep
hands
and
wires
clear
of
thefan
blades
.
The
cool-
ing
fan(s)
can
run
any
time
the
ignition
is
ON
.

"
For
greatest
safety,
coolíng
fan
and
coolant
tem-perature
switch
tests
shouldbe
performed
on
acoldengine
with
the
air
conditioning
off
.

Table
b
.
Auxiliary
Cooling
Fan
Switching

Temperatures

Switching
temperature
196°F(91°C)
210°F(99°C)

0012506

If
a
faulty
thermostat,
trapped
air,
or
a
restriction
in
the
sys-
tem
is
not
allowing
the
coolant
to
circulate
through
the
radia-
tor,
the
temperature
switch
will
not
close
and
the
auxiliary
cooling
fan
will
not
run
.
Before
making
the
tests
described
be-
low,
make
sure
the
thermostat
is
operating
correctly
as
de-
scribed
earlier
.
The
normal
switching
temperatures
for
the

dual
-speed
switch
are
listed
in
Table
b
.

NOTE-

Some
cars
covered
by
this
manual
may
have
an
alter-
nate
cooling
fan
switchwith
switching
temperatures
of
176%190W
(80%88°C)
.
When
replacing
the
switch
check
theswitching
specifications,
whichshouldbe
stamped
on
the
switch
body
.

1
.
If
coolant
is
circulating
at
normal
operating
tempera-
ture,
but
auxiliary
cooling
fan
does
not
run,
disconnect
connector
from
radiator
temperature
switch
and
make
tests
listed
in
Table
c
.

Table
c
.
Auxiliary
Cooling
Fan
Temperature

Switch
Tests

Wires
jumpered



Test



Test
resuits
conditions

Black/green
(terminal2)
and



Ignition
ON



Fan
runs
on
brown
(terminal
1)



low
speed

Black/gray
(terminal
3)
and



Ignition
ON



Fan
runson
brown
(terminal



I
1)



high
speed
2
.
If
fan
runs
only
when
powered
directly
by
jumpered
connector
and
hot
coolant
is
circulating
through
radia-
tor,
radiator
temperature
switch
is
most
likelyfaulty
.
Use
a
new
sealing
ring
when
replacing
switch

Tightening
Torque

"
Temperature
switch
to
radiator
......
15
Nm
(11
ft-Ib)

3
.
If
auxiliary
fan
does
notrun
when
powered
directly,
check
for
battery
voltage
at
temperature
switch
connec-
tor
(black/green
wire)
with
ignition
on
.
If
battery
voltage
is
not
present,
check
fuses
.
See
610
Electrical
Com-
ponent
Locations
.

RADIATOR
AND
COOLING
SYSTEM



170-
5

~r~nmm
a
00
0

Fig
.
4
.



Auxiliary
radiator
cooling
fan
low
speed
relay
(1)
and
high
speed
relay
(2)
in
power
distribution
box
.
(Relay
locations
may
vary
.)

Auxiliary
Cooling
Fan
Circuit
Fuses



Fig
.
5
.
Auxiliary
radiator
fan
resistor
(arrow)
.
"
Fuse16
.
...................
..
..
...
...
.5
amp

"
Fuse
41
(ex
.
M44
w/man
.
trans)
.
..
.
..
.....
30
amp

"
Fuse
48
(M44
w/man
.
trans
.
only)
..
.
..
.....
40
amp



COOLING
SYSTEM
SERVICE

0013034

4
.
If
no
faults
are
found,
remove
low
speed
relay
and
turn



Coolant,draining
and
filling

ignition
ON
.
See
Fig
.
4
.



1
.
Remove
expansion
tank
cap
.
Set
temperature
controls
"
Check
for
power
at
terminal
30
and
terminal
86
of
relay



to
full
warm
.
socket
.

"
Reinstall
low
speed
relay
and
repeat
testat
high
speed



WARNING
-
relay
socket
.
Fix
any
wiring
faults
found
.



Allow
the
cooling
system
to
cool
before
openlng
or

On
early
productioncars
(up
to
9/92)
:
If
fan
operates
only
on



draining
the
cooling
system
.

high
speed
and
no
electrical
faults
have
been
foundup
to
this
point,
usean
ohmmeter
to
check
that
fan
resistor
is
not
electri-



2
.
Place
3
ra
allo

ug
.



beneath
radiator
drain
plug
and
re-

cally
open
.
Resistor
is
mounted
on
auxiliary
cooling
fan
housing



move
drain
plg
.
See
Fig
.
6
.

behind
front
grille
.
See
Fig
.
5
.
Wiring
diagrams
for
the
radiator

cooling
fan
canbefoundunder
Electrical
Wiring
Diagrams
.



3
.
Place
3-g



pail
beneath
rear
of
engine
blo
.
Loos-
en
and
re

mlon

ove
engine
blockcoolant
drain
plug
k
.

COOLING
SYSTEM
SERVICE

170-6



RADIATOR
AND
COOLING
SYSTEM

Fig
.
6
.



Radiator
drain
plug
(arrow)
.

WARNING
-

Coolant
is
poisonous
.
Itis
especially
lethal
to
pets
.

Cleanup
spills
immediately
and
rinse
the
area
with

water
.

NOTE
-

The
block
drain
plug
is
located
on
the
exhaust
side
of
the
engine,
near
the
reas
of
the
engine
.

4
.
Reinstall
radiator
and
engine
block
drain
plugsusing

new
sealing
washers
.
Leave
heater
controis
on
full

warm
.

5
.
Using
a
coolantmixture
of
50%
antifreeze
and
50%
dis-

tilled
water,
fill
system
slowly
On
radiator
with
integral

expansion
tank,
bleed
cooling
system
as
described
be-

low
.

NOTE-

"
Tap
water
may
cause
corrosion
of
radiator,
engine
and
coolant
hoses
.

"
Coolant
can
often
be
reused
provided
itis
clean
and
less
than
twoyears
old
.
Do
not
reuse
coolant
when
re-
placing
damaged
engine
parts
.
Contaminated
coolant
may
damage
the
engine
or
cooling
system
.

Tabled
.
Cooling
System
Capacities

Engine



j
Capacity

4-cylinder



1
6
.5
liters
(6.9
qt)

6-cylinder
M50/M52



10
liters
(10
.6
qt)
S50US/S52US



10
.5
liters
(11
.1
qt)

COOLING
SYSTEM
SERVICE

Tightehing
Torques

"
Radiator
drain
plug
to
radiator
...
2-3
Nm
(18-27
in-lb)

"
Engine
block
drain
plug
to
block



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

Cooling
system,
bleeding

(radiator
with
integral
expansion
tank)

NOTE
-

On
radiators
with
a
separate
expansion
tank,
ableed

screw
is
not
provided
.
The
cooling
system
with
sepa-

rate
expansion
tank
is
self
bleeding
via
the
vent
hose

on
the
expansion
tank
.

Air
maybecome
trapped
in
the
system
during
filling
.

Trapped
air
can
prevent
proper
coolant
circulation
.
Whenever

the
coolant
is
drained
and
filled,
the
system
should
be
bled
of

trapped
air
.

1
.
With
engine
cold,
add
coolant
to
expansion
tank
until

level
reaches
COLD
(KALT)
mark
on
tank
.

2
.
Loosen
bleed
screw
on
radiator
expansion
tank
.
See

Fig
.
7
.

0011976

Fig
.
7
.



Cooling
system
bleed
screwon
radiator
(arrow)
.
Note
cold
level
mark
on
expansion
tank
.

3
.
M3
models
:
Loosen
bleed
screw
on
thermostathous-

ing
.

4
.
Set
temperature
controls
in
passenger
compartment
to

fui¡
warm
and
turn
ignition
on
position
(do
not
start
en-

gine)
.

5
.
Slowly
add
coolant
until
it
spills
from
bleed
screws
.

When
coolant
spillíng
from
bleed
screws
is
free
of
air

bubbies,
tighten
screws
.

6
.
Run
engine
until
it
reaches
operatíng
temperature
.
Af-

ter
engine
has
cooled,
recheck
coolant
level
and
top
up
as
necessary
.

CAUTION-

Always
use
genuine
BMW
coolant
or
its
equiva-

lent
to
avoid
the
formation
of
harmful,
clogging
de-

posits
in
the
cooling
system
.
Use
of
other
antifreeze
solutions
may
be
harmful
to
the
cooling
system
.

Tightening
Torque

"
Radiator
bleed
screw

to
thermostat
housing
...
.
.
........
8
Nm
(71
in-lb)

Belt-driven
cooling
fan,
replacing

1
.
Usinga32
mm
wrench
on
fan
clutch
nut,
turn
wrench

quickly
in
a
clockwise
direction
(working
from
front
of

car)
to
loosen
.
Spin
fan
off
pump
.
See
Fig
.
8
.

NOTE-

"
The
radiator
cooling
fan
nut(32
mm
wrench)
has
left-
hand
threads
.

"
The
nut
may
be
difficult
to
loosen
.
Use
a
tool
to
hold
the
coolant
pump
pulleystationary
.
BMW
hasa
spe-
cial
tool
forthis
purpose
(BMW
special
tool
no
.
115
030)
.

2
.
Remove
expansion
rivets
holding
shroud
to
radiator
.

See
Fig
.
9
.
Remove
fan
and
shroud
together
.

NOTE-

Store
the
removed
fan
clutch
assembly
in
an
upright
(installed)
positionto
prevent
lossof
clutch
fluid
.

RADIATOR
AND
COOLING
SYSTEM



170-
7

Fig
.
8
.



Radiatorcooling
fannut
(arrow)
.
Nuthas
left-hand
threads
.

3
.
To
replace
fan
clutch,
remove
fan
mounting
bolts
and

separate
clutch
from
fan
.
Fig
.
9
.



Fan
shroud
retaining
rivet
(arrow)
.
Pryout
center
pin
and
re

4
.
Installation
is
reverse
of
rernoval
.



move
rivet
.
Rivet
design
may
vary
depending
on
model
and

model
year
.

Tightening
Torques

"
Clutchnut
to
coolant
pump
(left-hand
threads)

Wíthout
BMW
tool
no
.
11
5
040
.....
40
Nm
(29
ft-lb)

With
BMW
tool
no
.
11
5
040
.
......
30
Nm
(22
ft-Ib)

"
Fan
to
viscous
clutch
...
.
..
.
......
10
Nm
(89
in-lb)

0013203

COOLING
SYSTEM
SERVICE

170-8



RADIATOR
AND
COOLING
SYSTEM

Electric
cooling
fan,
replacing

On
late
4-cylinder
models
(M44
engine)
with
manual
trans-
mission,
the
primary
cooling
fan
is
electrically
operated
and
is
mounted
on
the
engine
side
of
the
radiator
.

1
.
If
necessary,
remove
cover
from
top
of
radiator
.
See
Fig
.
10
.

0012505
Fig
.
10
.
Air
cover
in
back
of
radiator
.
Unclip
cover
from
fan
shroud
af-
ter
removing
mounting
screws
.

2
.
Disconnect
fan
harness
connector
at
bottom
left
of
ra-
diator
.

3
.
Remove
fan
shroud
mountingscrews
at
left
and
right
side
of
radiator
.
Lift
fan
assembly
straight
up
and
offra-
diator
.

4
.
Installation
is
reverse
of
removal
.
Be
sure
to
align
side
tabs
on
fan
housíng
with
retaining
tabs
on
radiator
when
reinstalling
fan
.

Auxiliary
cooling
fan,
replacing

The
auxiliary
electric
cooling
fan
is
mounted
behind
the
front
bumper,
in
front
of
the
A/C
condenser
.
There
aretwo
ver-
sions
of
auxiliary
fans
installed,
depending
on
model
and
en-
gine
installed
.

TType
1
(u
p
to
9192)

1
.
Remove
front
radiator
air
shroud
.
See
Fig
.
11
.

2
.
Remove
fan
mountingscrews
.
See
Fig
.
12
.

3
.
Tilt
fan
forward
.
Disconnect
electrical
harness
connec-
tor
before
lifting
fan
up
.

COOLING
SYSTEM
SERVICE

Fig
.
11
.
Front
radiator
air
shroud
fasteners
(arrows)
.

Fig
.
12
.
Version
1
auxiliary
fan
mountingscrews
(arrows)
.

NOTE
-

If
necessary,
remove
front
bumper
or
lowerengine
cov-
erto
access
electrical
harnessconnector
.

4
.
Installation
is
reverse
of
removal
.

l)
Type
2
(from
9192)
2
.
Remove
fan
mounting
screws
.
See
Fig
.
13
.

0013137

1.
Remove
front
bumper
and
radiator
grilles
.
See
510
Ex-
terior
Trim,
Bumpers
.

3
.
Angle
fan
up
and
forward,
disconnecting
electrical
har-
nessconnectorbehind
it
.
Remove
it
through
bumper
opening
.

Fig
.
13
.
Version
2
auxiliary
fan
mounting
screws
(arrows)
.
Front
bumper
hasbeen
removed
.

4
.
Installation
is
reverse
of
removal
.

Thermostat,
replacing

0013146

The
coolant
thermostat
is
instalied
in
a
housing
at
the
front

of
the
cylinder
head
.
See
Fig
.
14
.

Fig
.
14
.
Coolantthermostat
and
housíng
.

NOTE-

On
M44
engines,
the
thermostat
is
integrated
into
the
thermostat
housíng
.
If
the
thermostat
requiresreplace-
ment,
the
complete
thermostathousing
mustbe
replaced
.

RADIATOR
AND
COOLING
SYSTEM



170-
9

WARNING
-

Allow
the
cooling
system
to
cool
before
opening
ordraining
the
system
.

2
.
Remove
belt-driven
cooling
fan
and
fan
shroudas
de-

scribed
earlier
.

3
.
On
M52/S52US
engines
:
Unclip
wiring
duct
retaining
clips
and
remove
duct
from
above
thermostat
housing
.

Also
remove
engine
front
lifting
bracket
.

4
.
Remove
thermostat
housing
from
front
of
engine
.
See
Fig
.
15
.

Fig
.
15
.
Thermostat
housíng
shown
removed
(6-cylinder
engine)
.

NOTE-

Some
thermostats
have
a
direction
arrowor
venthole
near
the
edge
.
Install
the
thermostat
so
that
either
the
arrow
or
hole
are
at
thetop
.

CAUTION
-

Be
sure
to
reconnect
ground
wire(s)
at
thermostat
housing
mounting
bolt,
where
applicable
.

5
.
Remove
thermostat
.
Note
thermostat
direction
and
ori-

entation
before
removing
.

6
.
Insta¡¡
new
thermostat
and/or
thermostat
housing
using

new
O-ring
and
gasket(s)
as
necessary
.

oo131ss



7
.
Installation
is
reverseof
removal
.
Fill
system
with
cool-

ant
as
described
under
Coolant,draining
and
filling
.

Tightening
Torques

1
.
Drain
radiator
as
described
above
under
Coolant,



"
Thermostat
housing
cover

draining
and
filling
.



to
housing
orcoolant
pump
..
..
....
10
Nm
(89
in-lb)

"
Engine
lifting
bracket
bolt
to
thermostat
housing

(M52/S52US
engine)(M8)
....
..
...
22
Nm
(17
ft-Ib)

COOLING
SYSTEM
SERVICE

170-10



RADIATOR
AND
COOLING
SYSTEM

Coolant
pump,
replacing

The
engine
coolant
pump
is
mounted
in
the
frontof
the
en-

gine
on
the
timing
cover
.
See
Fig
.
16
.

Fig
.
16
.
Coolant
pump
mounted
on
timing
cover
.

NOTE-

Onlyreplacement
coolant
pumps
with
metal
¡mpellers
should
be
installed
.
Pumps
with
plastic
impellers
should
not
be
used
.

1.
Drain
cooling
system
as
described
earlier
.

0013197

WARNING
-

Allow
cool¡ng
system
to
cool
before
open¡ngor
drain¡ng
system
.

2
.
Remove
primary
cooling
fan
shroud
and
cooling
fan
(belt-driven
or
electric)
as
described
earlier
.

Fig
.
17
.
Engine
drive
belt
tensioner
being
released
on
M44
engine
.
Pry
off
tensioner
cover
and
then
lever
tensioner
in
counterciock-
wise
direction
(as
facing
engine)
and
slip
belt
off
pulleys
.

Fig
.
18
.
Drive
belt
tensioner
being
released
on
M52
engine
.
Pry
off
3
.
Disconnect
hoses
from
thermostat
housing
.
Unbolt



tensioner
cover
and
then
lever
tensioner
clockwise
(as
facing
thermostat
housing
from
front
of
cylinder
head
.



engine)torelease
belt
tension
.

4
.
Remove
coolant
pump
drive
belt
.
See
Fig
.
17
or
Fig
.
18
.

NOTE-

-
Mark
direction
of
drive
belt
rotation
if
reusing
belt
.



"
The
6-cylinder
coolant
pump
¡s
mounted
on
studs
and
retained
by
nuts
.
"
Severa¡
drive
belt
and
tensioner
configurations
havebeenused
in
E36
models
.
Refer
to
020
Maintenance
Program
and
640
Heating
and
Air
Conditioning
.

5
.
Remove
coolant
pump
pulley
from
pump
.

6
.
Remove
mounting
fasteners
from
pump
.

COOLING
SYSTEM
SERVICE

NOTE-

"
The
4-cylinder
coolant
pump
¡s
mounted
us¡ng
two
dif-
terent
length
bolts
.
Note
where
thelonger
bolt
fits
dur-
ing
disassembly
.

0011989

7
.
Insert
twoscrews
(M6)
in
tapped
bores
and
tighten
uni-
formly
until
pump
is
free
from
timing
chain
cover
.
See
Fig
.
19
.

GENERAL
.
.
.......
.
......
.
...
.
.
.
.
.
...
180-1



Exhaust
system,
removing
and
installing
.
...
.180-3

EXHAUST
SYSTEM
REPLACEMENT
.
...
180-1



Exhaust
manifolds,
removing
and
installing
.
.
.180-5

GENERAL

The
exhaust
system
is
designed
to
be
maintenance
free,
al-
though
regular
inspection
is
warranted
due
to
the
harsh
oper-
atingconditions
.
Under
normal
conditions,
the
catalytic

converter
does
not
require
replacement
unless
it
is
damaged
.

On
1996
and
later
cars,
a
pre-
and
post-catalytic
converter

oxygen
sensor
is
used
at
each
catalytic
converter
.
Be
sure
to

take
care
when
removingthe
system
not
to
damage
the
sen-



EXHAUST
SYSTEMREPLACEMENT
sors
.

See
130
Fuel
Injection
for
information
on
testing
oxygen

sensors
.

NOTE-

OnM52
engines,
two
resonator
pípes
(short
and
long)
are
incorporated
into
the
rear
muffler
assembly
.
See
Fíg
.
1
.
An
exhaust
flap
is
integrated
into
the
outlet
side
of
the
short
pipe
.
The
flap
is
operated
by
a
vacuum
ac-
tuator
via
the
Siemens
MS
41
.1
engine
control
mod-
ule)
.
The
flap
is
closed
at
engine
speeds
below
2,500
rpm
.
This
allows
exhaust
gasses
to
flow
through
the
long
resonator
pipe
and
reduce
noise
.
Above
2,500rpm,
the
exhaust
flap
is
open
(no
vacuum
applied
to
the
actuator)
and
allows
exhaust
gasses
to
flow
through
the
short
pipe
for
maximum
performance
.

180
Exhaust
System

0013101

Fig
.
1
.



Rear
muffler
(active
silencer
usedon
M52
engines)
.
Vacuum

operated
flap
(A)
changesbetween
short
and
long
pipes,
de-

pending
on
engine
speed
.

EXHAUST
SYSTEM



180-1

WARNING
-

Exhaust
gases
are
colorless,
odorless,
and
very
toxic
.
Run
the
engine
only
ín
a
well-ventilated
area
.
Immediately
repair
any
leaks
in
the
exhaust
system
or
structural
damage
to
the
car
body
that
might
al-
lowexhaust
gases
to
enter
the
passenger
compart-
ment
.

Exhaustsystem
components
are
detailed
in
Fig
.
2
through

Fig
.
4
.

New
fasteners,
clamps,rubber
mounts,
and
gaskets
should

be
used
when
replacing
exhaust
components
.
A
liberal
appli-
cationof
penetrating
oil
to
the
exhaustsystem
nuts
and
bolts
in
advance
may
make
removal
easier
.

WARNING
-

"
The
exhaust
system
and
catalytic
converter
op-
erate
at
high
temperatures
.
Allow
components
to
cool
before
servicing
.
Wear
protectíve
clothíng
to
prevent
bums
.
Do
not
use
flammable
chemicals
near
a
hot
catalytic
converter
.

"
Old,
corroded
exhaust
system
components
crumble
easíly
and
often
have
exposed
sharp
edges
.
To
avoid
injury,
wear
eye
protection
and
heavy
gloves
when
working
with
old
exhaust
parts
.

EXHAUST
SYSTEM
REPLACEMENT

T

180-2



EXHAUST
SYSTEM

a

EXHAUST
SYSTEM
REPLACEMENT

Fig
.
2
.



Exhaust
systemon
1992-1995
6-cylinder
engines
.
3251
(M50)
exhaust
system
shown
.

E~

)l-,malo
m~=

i

32592-95

1
.



Front
pipe
with
catalytic
convertor



6
.



Bracket



11
.



Bracket/clamp
(2)



16
.



Rear
pipewith
muffler
2
.



Gasket
(2)



7
.



Bracket
(2)



12
.



Rubber
mounting
ring
(2)



17
.



Rubber
mount
3
.



Exhaust
manifold



8
.



Bracket



13
.



Flange



18
.



Support4
.



Exhaust
manifold



9
.



Bracket



14
.



Gasket
(48mm)



19
.



Bracket
5
.
Manifold
gasket



10
.
Oxygen
sensor



15
.
Gasket
(48mm)

eme°"



k
:I>
-
8a

1
.



Exhaust
manifold



7
.



Front
pipe
with
catalytic
con-



9
.



Bolt
(M8X90)



14
.



Brackets
(rear
muffier)
2
.



Nut
(M10)



vertor



10
.



Compression
spring



15
.



Rear
muffler
and
pipe
3
.
Gasket
(clty
.
2)



8
.



Oxygen
sensor
(regulating)



11
.



Self-lockingnut
(M8



16
.



Bracket
(transmission)
4
.
Gasket



-tightento
55
Nm
(41
ft-Ib)



-always
replace



17
.



Brackets
(transmission)
5
.



Nut



8a
.



Oxygen
sensor
(monitoring)



12
.



Bracket
(rear
pipe)
6
.



Bolt
(M8X55)



-tightento
55
Nm
(41
ft-Ib)



13
.



Rubber
mounting
ring
(9ty
2)

Fig
.
3
.



Exhaust
systemon
1996-1998
4-cylinder
(M44)
engine
.1992-1995
4-cylinder
engine
exhaust
system
is
similar
.