2001 BMW 540i AC line

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170-5
Radiator and Cooling System
Fan switch calibration (M52, M62 engine)
coniprairoi OUt rlgnal
Auto. ciimilte ~ontioi inpuls via CAN bus
Electric fan activation:
Low speed
91°C (196°F)
High speed 104' C (21 9' F)
< In models manufactured after 911998 (M52 TU engine, M54
engine.
M62 TU engine), the electric cooling fan is controlled
by the engine control module (ECM) via the output final
stage.
The output final stage is mounted on the fan housing, next to
the fan motor. The fan is operated using a pulse width modu-
lated signal. Fan circuit wiring is protected by a 50-amp fuse.
Electric fan activation is based on the following inputs to the
ECM:
Radiator outlet temperature
Calculated catalytic converter temperature
Vehicle speed
* Battery voltage
Calculated
A/C pressure
When the vehicle is first started, the ECM activates the elec-
tric fan briefly at 20% of its maximum speed, then switches
off. This is for diagnostic monitoring. The voltage generated
by the fan when it slows down (acting as a generator) must
match the stored rpm values in the fan output stage toconfirm
that the fan is operating correctly.
NOTE-
If the ECM fault memory indicates a cooling fan fault, check
that the fan is not seized and that it spins freely.
When
A/C is switched ON, the electric fan is not immedi-
ately turned on.
After the engine is switched
OFF the fan may continue to
run at varying speeds for up to 10 minutes, based on cal-
culated catalyst temperature.
Transmission fluid heat exchanger
Automatic transmission fluid lines circulate transmission fluid
(ATF) to and from a heat exchanger at the radiator.
All 6-cylinder
models andV-8 models produced to 911998 are
equipped with a transmission cooler located in a cooling cas-
sette in front of the radiator.

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. --
Radiator and Cooling system/
4 Pry out expansion rivets (A) on left and right side of fan
shroud. Loosen hose clamp
(6) and remove hose from ex-
pansion tank.
Remove expansion tank: Remove expansion tanlc cap, vent plug
(A) and tank retain-
ing clips (arrows).
Lift expansion
tanlc upward and off lower retaining lugs.
Push shroud back to expose expansion tank vent line. Re-
move line.
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 mrn wrench) has left-hand
threads.
Disconnect electrical harnesses from
AUC (air quality) sen-
sor and coolant level sensor.

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Exhaust system1
Exhaust manifold removal procedures are organized accord-
ing to engine code. If necessary, see
100 Engine-General
for engine code and application information.
Exhaust manifolds, removing and installing
(M52 engine)
4 Exhaust manifolds for the M52 engine.
Always use new retaining nuts and gaskets when removing
and installing the exhaust manifolds.
- With exhaust system cold, raise and support car for access
to exhaust system.
WARNING -
Do not work under a lined car unless it is solidly supported on
jack stands designed for that purpose. Never work under a
car that is supported solely by a jack.
- Disconnect secondary air check valve and pipe from exhaust
manifold.
- Unbolt front exhaust pipe@) from exhaust rnanifold(s)
- Remove exhaust support bracket from transmission.
- Loosen and remove nuts from exhaust manifolds and remove
manifolds. Discard nuts and gaskets.
NOTE-
On cars with oxygen sensors mounted in the exhaust mani-
folds, use care when removing manifolds.
To be safe, remove
the sensors from the manifolds before removing manifolds.
- Installation is reverse of removal
Coat exhaust manifold mounting studs with copper paste
before installing new nuts.
Install manifold gaskets with arched side facing manifolds.
Tightening torque
Exhaust manifolds
to cylinder head 20 Nm (15 ft-lb)

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Tool for bleeding clutch hydraulics (Tool No. 21 5 030)
21 5 030 I
The clutch is hydraulically actuated by the master and slave
cylinders. With the self-adjusting clutch
(SAC), clutch disc
wear is automatically taken up through the self-adjusting
pressure plate springs, making pedal feel consistent through-
out the life of the clutch.
A soft or spongy feel to the clutch pedal, long pedal free-play,
or grinding noises
from the gears while shifting can all indi-
cate problems with the clutch hydraulics. In these circum-
stances it is best to
star? with a clutch fluid flush, followed, if
necessary, by replacement of the hydraulic parts.
NOTE-
The clutch hydraulic system shares the fluid reservoir and flu-
id with the brake hydraulic system.
Clutch hydraulic system,
bleeding and flushing
If the clutchlbralte fluid is murky or muddy, or has not been
changed within the last two years, flush the system and
change the fluid. Flushing the old fluid from the clutch lines is
done using a bralte system pressure bleeder.
- Remove brake fluid reservoir cap. Using a clean syringe, re-
move brake fluid from reservoir. Refill reservoir with clean
DOT
4 bralte fluid.
Worlting inside engine compartment, remove left
interiorven-
tilation filter housing:
Release 3 plastic taps
(A) on duct. Earlier models use a
single release latch.
Rotate duct inward to remove.
Disconnect electrical harness to hood position switch.
Remove filter housing cover.
Release spring lock
(B) on interior ventilation housing and
remove housing.

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21 0-6
1 Clutch
Hydraulic system, bleeding
(using
BMW special tool 21 5 030)
4 Working underneath transmission, remove slave cylinder
mounting nuts (arrow) from clutch housing and remove
cylinder. Leave fluid line attached.
4 Use BMW special tool 21 5 030 to press slave cylinder push-
rod completely into slave cylinder.
Hold slave cylinder so that bleeder valve is at highest point.
Open bleeder valve and allow brake fluid to expel until
clean fluid comes out, free of air bubbles.
* Close bleeder valve and disconnect pressure bleeding
equipment from fluid reservoir.
Slowly unscrew and detach special tool 21
5 030 from
slave cylinder.
CAUTION-
Do not remove tool if hydraulic system is pressurized.
- Reinstall slave cylinder.
Tightening torque Slave cylinder to transmission case
22 Nm (1 6 ft-lb)
- Slowly operate clutch pedal about 10 times. Fill reservoir with
clean fluid as necessary.
Clutch master cylinder, replacing
The clutch master cylinder is mounted to the pedal assembly
directly above the clutch pedal.
Working inside engine compartment, remove left interior
ventilation filter housing:
Release 3 plastic taps
(A) on duct. Earlier models use a
single release latch.
Rotate duct inward to remove
Disconnect electrical harness to hood position switch.
Remove filter housing cover.
Release spring
loclc (B) on interior ventilation housing and
remove housing.

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21 0-8
Clutch
4 Remove hydraulic line locking clip (1) and pull line (2) off
master cylinder.
CAUTION-
. To prevent brake fluidspill, wrap clutch master cylinder with
shop rags when removing hydraulic fluid lines from master
cylinder.
* Brake fluid damages paint andstains carpets. Clean off
any brake fluid on or
in the car immediately.
- Remove master cylinder with supply hose
4 Remove switch module from master cylinder.
Press locking button
(A) to release harness connector.
Pull harness connector
(8) off switch module.
Use screwdriver to lever
off switch module (C).
- Installation is reverse of removal.
CA UTlON-
Switch module must snap firmly into place on the master cyl-
inder during installation.
Tightening torques
Clutch master cylinder to pedal cluster
10 Nm (89 in-lb)
Fluid line
to master cylinder or slave cylinder 17 Nm (13 ft-lb)
- Fill fluid reservoir with clean fluid. Bleed clutch hydraulics as
described earlier.
Clutch slave cylinder, replacing
4 Working inside engine compartment, remove left interiorven-
tilation filter housing:
Release
3 plastic taps (A) on duct. Early models: release
latch.
Rotate duct inward to remove.
Disconnect electrical harness to hood position switch.
Release spring lock (B) on interior ventilation housing and
remove housing.
- Pinch off brake fluid supply hose to clutch master cylinder us-
ing BMW special tool
13 3 01 0 or equivalent hose clamping
tool.

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- Raise and safely support vehicle
WARNING-
Make sure the car is stable and well supporied at all times.
Use a professional automotive /iff orjack stands designed for
the
ournose. A floor jack is not adeouate suooort.
- If necessary, remove transmission splash shield.
- Disconnect fluid line from slave cylinder on lefl side of trans-
mission. Place pan under hose to catch dripping fluid.
4 Working underneath transmission, remove slave cylinder
mounting nuts (arrow) from clutch housing and remove
cylinder.
- Installation is reverse of removal, noting the following:
Check for wear on slave cylinder. Any wear except on tip is
caused by misalignment of clutch components.
Lightly coat
pushrod tip with molybdenum disulfide grease
(MolyltoteIB Longterm or equivalent).
. During installation be sure pushrod tip engages recess in
clutch release lever.
Fill fluid reservoir with clean fluid.
. Bleed clutch hydraulics as described earlier.
Tightening
toraues - -.
Clutch slave cylinder to transmission 22 Nm (16 R-lb)
Fluid line to slave cylinder 17 Nm (13 ft-lb)
The transmission must be removed from the engine to access
the clutch mechanical components. It is recommended that
the clutch disc, pressure plate and release bearing be re-
placed during a clutch overhaul.
Besure tocheck the bottom of the bellhousing foroil. If engine
oil is found, check for a faulty rear crankshaft main oil seal.
See
119 Lubrication for rear main seal replacement.
Clutch variations
Two versions of the clutch are used:
1997 528i (6 cylinder) uses traditional clutch components.
All
540i (V-8) and 1998 and later 6 cylinder models from
use a self-adjusting clutch (SAC).

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21 0-1 2
Clutch
Release bearing
Release
bearin
- lnspect flywheel for scoring, hot spots, cracks or loose or
worn guide pins. If any faults are found, replace flywheel as
described later.
- lnspect transmission pilot bearing in end of crankshaft. The
bearing should rotate smoothly without play. If necessary,
replace as described later.
4 lnspect and clean release bearing lever. Apply a thin coat of
grease to release bearing lever lubrication points (arrows).
Clean and lightly lubricate clutch disc splines and transmis-
sion input
shaft splines.
4 Checlc release bearing ball stud and spring retainer. Replace
if damaged or worn.
CAUTION--
On S6S 420G transmission, always replace release bearing
ball stud and retainer spring.
- Clean release bearing guide sleeve.
CA U TIOG
Do not grease guide sleeve. If guide sleeve is greased,
release bearing may stick to it.
Flywheel, removing and installing
(6 cylinder engine)
- lnspect flywheel for scoring, hot spots, cracks or loose or
worn guide pins. Replace flywheel if any faults are found.
Lock flywheel with BMW special tool
11 2 170. Remove
pressure plate and clutch disc as described earlier.
- Loosen and remove flywheel mounting bolts. Remove
flywheel.
- Clean flywheel bolt threads in crankshaft.