1999 BMW 540i clutch

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Fuel Injection I
Connector X60004 (continued)
8 10
11
12
13
14
15
16
9
Output 0
Input
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
39
llnput lsignal l~oolant outlet temperature sensor
Output
Output
Ground
Input
Output
I I - I
40 /output Istart signal Istarter relay
Pedal position sensor (PWG), signal
Output Input
Output
input
Input
Input
Input
Input
Input
input
Input
Output
Input/-output
Input/-output
37
Connector X60003
Pedal position sensor
Fuel pump relay, activation
Oil pressure indicator Pedal position sensor (PWG), ground
Pedal position sensor (PWG), signal
Pedal position sensor (PWG), power supply
Not used
Not used Fuel
pump relay
Instrument cluster
Pedal position sensor
Pedal position sensor
Pedal position sensor
Engine speed signal output (TD)
Not used
Signal
back-up light
DM-TL (diagnostic module,
tank leakage)
Signal oil level sensor
Right rear wheel speed, signal
Clutch pedal position switch, signal
Brake light switch, signal
Not used
Voltage supply, terminal
15
Data link, MFL (multi-function steering wheel)
Brake light test signal
AJC compressor signal
DM-TL (diagnostic module, tank
leakage)
Not used
Diagnosis signal
TxD
Communication link (EWS)
Not used
Not used
CAN-BUS hiqh
38 1 Ground l~round I Coolant outlet temperature sensor
OED II plug
Integrated instrument cluster control module (IKE)
Light module
ABSIDSC control module
Clutch pedal position switch
Brake light switch
Fuse
F14
Airbag contact coil spring
Brake light switch
Heating and
A/C control module
OBD
II plug
Electronic immobilizer (EWS)
CAN-Bus link
CAN-Bus link
Input/-output CAN-Bus low

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176 Radiator and Cooling System
General ........................... .I7 0.2
Special tools
........................ .I7 0.2
Cooling system overview
(M52 TU shown. others similar) ......... .I7 0.3
Coolant pump
....................... .I7 0.3
Thermostat
......................... .I7 0.3
Mechanical thermostat (M52 engine)
..... .I7 0.4
Electrically heated thermostat
.......... .I7 0.4
Radiator and expansion tank
........... .I7 0.4
Mechanical cooling fan with viscous clutch
.I7 0.4
Electric (auxiliary) cooling fan ........... .I7 0.4
Transmission fluid heat exchanger
....... .I7 0.5
Warnings and cautions
................ .I7 0.7
Troubleshooting ................... .I7 0.7
Cooling system inspection
............. .I7 0.8
Cooling system pressure test
........... .I7 0.9
Combustion chamber leak test
......... .I7 0.10
Thermostat
........................ .I7 0.1 0
Cooling System Service ........... 170-10
Coolant. draining and filling
(6-cylinder models)
.................. 170-1 0
Coolant. draining and filling (V-8 models)
. 170-12
Cooling system. bleeding
............. 170-14
Mechanical (viscous clutch) cooling fan.
removing and installing
............... 170-14
Electric cooling fan.
removing and installing
............... 170-15
Thermostat. removing and installing
(M52engine) ....................... 170-16
Thermostat. removing and installing
(M52 TU or M54 engine) .............. 170-17
Thermostat. removing and installing (V-8 models)
....................... 170-1 8
Coolant pump. replacing (6-cylinder models)
.................. 170-1 9
Coolant pump. replacing (V-8 models) ... 170-20
Radiator. removing and installing
....... 170-22
Expansion tank. removing and
installing . . 170-24

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I Radiator and Cooling System
This section covers component repair information for the en-
gine cooling system.
Heater core replacement is covered in
640 Heating and Air
Conditioning.
Special tools
Special tools are necessaryfor belt-driven fan clutch removal
and also for pressure testing the cooling system.
4 Cooling fan counterhold wrench
(Tool No. BMW
11 5 030)
4 Cooling fan wrench
(Tool No. BMW
11 5 040)
< Expansion tank cap test adaptor
(Tool No.
BMW 17 0 007)
17 0 002 4 Cooling system pressure tester set
1 17 o 005 (Tool No. BMW 17 0 OOZi17 0 005)

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-
I Radiator and Cooling System
Mechanical thermostat
(M52 engine)
4 The mechanical thermostat relies on coolant temperature to
operate. While coolant is cold, it remains closed, and circu-
lating coolant bypasses the radiator for rapid engine warm
up. At higher coolant temperature, the thermostat progres-
sively opens to allow coolant flow through the radiator, thus
controlling engine temperature. Port
A restricts coolant flow
from radiator, and port
B restricts coolant flow to radiator.
Electrically heated thermostat
4 The electrically heated thermostat is DME map-controlled.
The engine control module (ECM) activates the thermostat to
maintain engine coolant temperature within a narrow range.
In case of failure of the electronics, the mechanical function of
the thermostat acts as a fail-safe.
Radiator and expansion tank
The radiator is a crossflow design. An expansion tank pro-
vides for coolant expansion at higher temperatures and easy
monitoring of the coolant level.
On cars with automatic transmission, ATF is circulated
through an additional heat exchanger (ATF cooler).
Mechanical cooling fan with viscous clutch
The mechanical cooling fan is belt-driven via a viscous fluid
coupling (clutch) attached to the front of the coolant pump.
The fan clutch controls the speed of the fan based on the tem-
perature of the air flowing through the radiator core.
Electric (auxiliary) cooling fan
The electric cooling fan is mounted on the bumper side of the
radiator.
In models manufactured up to
911 998 (M52 or 1997 M62 en-
gine), the electric cooling fan is controlled by a dual tempera-
ture fan switch mounted in the side of the radiator.

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170-8
I Radiator and Cooling System
Common cooling system faults can be grouped into one of 4
categories:
Cooling system
lealts
Poor coolant circulation
Radiator cooling fan faults
Electrical/electronic faults
Cooling system inspection
- Check that coolant pump drive belt tensioner is functioning
properly and that belt tension is correct. Belt tensioner sys-
tems for the different models are shown in
020 Maintenance.
- Check condition of coolant pump drive belt.
- Checlc coolant hoses for cracks or softness. Checlc clamps
for looseness. Check coolant level and check for evidence of
coolant
lealts from engine.
- Check that radiator fins are not blocked with dirt or debris.
Clean radiator using low-pressure water or compressed air.
Blow outward, from engine side out.
- To check coolant pump:
Remove mechanical cooling fan. See Mechanical
(vis.
cous clutch) cooling fan, removing and installing.
Remove drive belt from coolant pump pulley. See
020
Maintenance.
Firmly grasp opposite sides of pulley and check for play in
all directions.
Spin pulley and check that shaft runs smoothly without
play.
NOTE-
The coolant provides lubrication for the pump shaft, so an oc-
casional drop of coolant
lealing from the pump is acceptable.
If coolant drips steadily from the vent hole, replace the pump.
- At normal engine operating temperature, cooling system is
pressurized. This raises boiling point of coolant.
Leaks may
prevent system from becoming pressurized. If visual evi-
dence is inconclusive, pressure test cooling system as de-
scribed later to help pinpoint hard-to-find leaks.
- If cooling system is full of coolant and holds pressure:
- Use an appropriate scan tool to interrogate engine control
module (ECM) for radiator fan or DME control circuit faults.
Checlc for loose or worn drive belt.
0 Test for failed thermostat or coolant pump impeller. Some
pumps may be fitted with plastic impellers.

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Radiator and Cooling System
Cooling system, bleeding
Trapped air in the cooling system can prevent proper coolant
circulation and overheating. Wheneverthe coolant is drained
and filled, bleed the cooling system to remove trapped air.
4 Loosen bleed screw (arrow) on radiator expansion tank.
- Set temperature controls in passenger compartment to full
warm, set blower to low setting and turn ignition to
ON posi-
tion (do not start engine).
CAUTIOIG
On late model cars with latent heat pump, do not turn ignition
to ON position.
- Slowly add coolanUdistilled water mixture to expansion tank
until it spills from bleed screw. When coolant spilling from
bleed screws is free of air bubbles, tighten screw and replace
cap on expansion tank.
Run engine until it reaches operating temperature,
- After engine has cooled, recheck coolant level.
Top up so that coolant level indicator is at MAX.
- If trapped air cannot be bled manually, pressure-bleed sys-
tem using cooling system pressure tester.
CA UTlON--
Always use genuine BMW coolant or its equivalent to avoid
the formation of harmful, clogging deposits
in the cooling sys-
tem.
Tightening torque
Radiator bleed screw to radiator 2.5 Nm (22 in-lb)
Mechanical (viscous clutch) cooling fan,
removing and installing
The procedure given here describes the removal of the me-
chanical fan and fan shroud. It is possible to remove the fan
without the shroud.
< Working at top of fan shroud:
Remove expansion tank bleed screw (arrow) and expan-
sion tank locking tabs.
Push top of expansion
tank toward engine and lift to free
from lower mounts.
- Remove two expansion rivets in upper corners of fan shroud.
Unclip expansion tank bleed hose located under shroud.

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Radiator and Cooling System
Remove rubber trim strip between top of shroud and radiator.
Using 32 mm wrench
(BMW special tool 11 5 040) on fan
clutch nut (arrow), turn wrench in a clockwise direction
(working from front of car) while counterholding pulley with
BMW special tool
11 5 030. Spin fan off coolant pump.
NOTE-
The radiator cooling fan nut (32 mm wrench) has left-hand
threads.
Unclip AUC (air quality) sensor from shroud,
M54 engine: Disconnect auxiliary coolant pump from base of
fan shroud.
Lift fan and shroud together out of engine compartment.
To replace fan clutch, remove fan mounting bolts and sepa-
rate viscous clutch from fan.
Installation is reverse of removal.
Tightening
torques
Clutch nut to pump
Without
BMW tool 11 5 040 40 Nm (29 ft-lb)
With BMW tool 11 5 040 30 Nm
(22 ft-lb)
Fan to viscous clutch 10 Nm (89 in-lb)
Electric cooling fan, removing and
installing
The electric cooling fan is mounted behind the front bumper,
in front of the
A/C condenser.
- Remove front bumper. See 510 Exterior Trim, Bumpers.
- Remove left and right headlights. See 630 Lights,
- Where applicable, detach horizontal air ducts behind front
bumper and fold to side.
- Disconnect fan electrical connector on right side of radiator
shroud and lay aside.
- Detach wire loom from air duct in front of cooling fan
- Pry out expansion rivets holding air duct. Slide air duct down-
ward to remove.

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170-1 6
I Radiator and Cooling System
- Remove fan and fan shroud mounting fasteners. Slide fan
and fan shroud downward to remove.
- Reinstallation is reverse of removal.
Thermostat, removing and installing
(M52 engine)
The coolant thermostat is installed in a housing at the front of
the engine.
- Drain coolant from radiator and engine block. See Coolant,
draining and filling (6-cylinder models).
WARNING -
Allow the cooling system to cool before opening or draining
the system.
- Remove mechanical cooling fan and fan shroud. See Me-
chanical (viscous clutch) cooling fan, removing and in-
stalling.
- Disconnect coolant hoses from thermostat housing.
- Remove thermostat housing from front of engine.
- Remove thermostat. Note thermostat direction and orienta-
tion before removing.
- Installation is reverse of removal, noting the following:
- Use new O-ring and gasket(s) when installing thermostat
and housing.
NOTE-
Some thermostats have a direction arrow or vent hole near
the edge. Install the thermostat so that either the arrow or
hole are at the top.
Fill system with coolant as described in Coolant, draining
and filling (6-cylinder models).
CAUTION-
Be sure to reconnect ground wire@) at thermostat housing
mounting bolt, where applicable.