1997 BMW 525i cool

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121-1
121 Battery. Starter. Alternator
General ........................... .I2 1.2
Special tools ........................ .I2 1.2
Engine electrical system ............... .I2 1.2
Battery Safety Terminal ............... .I2 1.3
Warnings and cautions ................. 121 -4
Battery ............................ 121-5
Battery testing ...................... .I2 1.5
Hydrometer testing ................... .I2 1.5
Battery open-circuit voltage test ......... .I2 1.6
Battery load voltage test ................ 121 -6
Closed-circuit current measurement ..... .I2 1.7
Battery charging ...................... 121 -9
Battery safety terminal, replacing ......... 121-9
Alternator (generator) ............. .I2 1.10
Alternator. basic .................... .I2 1.11
Alternator with multi-function
control (MFR)
...................... .I2 1.11
Water-cooled alternator ............... 121 -12
Charging System Troubleshooting . 121-12
Charging system quick-check .......... 121-13
Charging system. checking ............ 121-13
Alternator. removing and installing
(6-cylinder engine)
.................. 121 -1 5
Alternator. removing and installing
(M62 engine. air cooled)
.............. 121-16
Alternator. removing and installing
(M62 TU engine. water cooled) ......... 121-1 8
Starter ........................... 121 -1 9
Starter troubleshooting ............... 121 -1 9
Starter. removing and installing
(6-cylinder engine)
.................. 121-20
Starter. removing and installing
(V-8 engine)
........................ 121 -21
Solenoid switch. removing and installing . . 121-23

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121-10
I Battery, Starter, Alternator
- Strip approximately 15 rnm (0.6 in) of insulation from cable
end.
terminal harness
Shrink insulation
Terminal connector
4 Push terminal connector of new cable over stripped end of
old cable. Tighten clamp.
- Slip shrink-fit insulation over positive cable. Attach new safe-
ty harness to end of positive cable. Shrink insulation with hot
air blower.
- Reinstall cable in cable bracket and attach to battery.
- Reattach negative battery cable. Reinstall luggage cornpart-
rnent trim pieces.
- Use BMW scan tool DlSplus or equivalent to read out airbag
control module fault memory. Correct faults, then clear mem-
ory.
1 1 4 Various versions of alternators have been used in E39
vehicles. See Table e.
Table e. Alternator application chart
Model Alternator type
Air cooled, 90 amp or 120 amp
Air cooled, with multi-function control
(MFR), 120 amp or 140 amp
Air cooled with multi-function control
(MFR), 120 amp or 140 amp
540i 1997 Air
cooled. 120
amp or 140amp sazrz~orsl 1998 ~~~ ~ .~ . ...~ ~ ~-~~~~ Air cooled; with integrated mu~ii-
function control (MFR). 120 amp 140
amp 1999-2002 Water
cooled, with integrated multi-
function control (MFR), 90-150 amp
(variable output)

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Battery, Starter, Alternator
Water-cooled alternator
The water-cooled alternator, used on 1999 and later M62 TU
engines, is a sealed unit housed inside the engine block wa-
ter jacket. It is cooled via the engine cooling system. It is a
"brushless" sealed unit that cannot be serviced. Maintaining
consistent alternator temperatures increases the life span of
the alternator, and elimination of the alternator cooling fan re-
duces alternator noise
significantly.
The M62 TU water-cooled alternator incorporates load start
reduction. This function is intended to shorten the duration of
engine starting, particularly at low ambienttemperatures. The
current load is limited to
20 amps during starting in order to re-
duce alternator braking torque on the engine. Following the
current limiting phase, full power output is then progressively
reached.
Charging system diagnostics requires special test equip-
ment. If the test equipment is not available, charging system
fault diagnosis can be performed by an authorized
BMW
dealer or other qualified repair shop. See Table a. Battery,
alternator and starter troubleshooting for general electri-
cal component troubleshooting.
Before checking the alternator, make sure the battery is fully
charged and capable of holding a charge. Check that the bat-
tery terminals are clean and tight and the alternator drive belt
is properly tensioned and not severely worn.
NOTE-
Some model require up to 15 second to reacli full alternator
output.
CA UTIOG
If the charge indicator light in the instrument cluster remains
on, the charge warning circuit in the instrument cluster may
be faulty. Check that the ground lead is securely
affached to
the grounding stud on the cylinder head
(A). Replacing the
instrument cluster before repairing the ground lead will both
damage the instrument cluster and cause the failure to
reoccur.

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Battery, Starter, ~lternatorl
Alternator, removing and installing
(6-cylinder engine)
A replacement alternator should have the same rating as the
original. Alternator manufacturer and ampere rating are nor-
mally marked on the alternator housing.
- Disconnect negative (-) battery cable.
CAUTION-
Prior to disconnecting the batteg read the battery discon-
nection cautions given
in 001 General Warnings and Cau-
I tions.
Remove complete air filter housing:
Loosen intake duct hose clamp
(A) at throttle assembly.
Loosen clamp and remove idle control hose from intake
duct
(B) and disconnect idle speed control valve electrical
harness connector.
Disconnect electrical harness connector
(C) from mass air
flow sensor.
* Remove air filter housing mounting screw (D),
Disconnect vent tube (E).
Loosen air intake duct clamp (F).
Carefully lifl air filter housing out of engine bay.
Remove alternator drive belt. See belt removal procedures in
020 Maintenance.
- Remove radiator cooling fan and fan shroud. See 170 Radi-
ator and Cooling System.
NOTE-
The radiator cooling fan nut (32 mm wrench) has left-hand
threads.
- Unbolt power steering fluid reservoir and bracket. Suspend to
one side without detaching fluid hoses.
- Disconnect alternator air cooling tube.
- Disconnect wiring from rear of alternator.
'4 Remove upper and lower mounting bolts (arrows) and lift
alternator.
If idler pulley for belt interferes, remove pulley cover and
retaining bolt to remove pulley. out

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121-16
Battery, Starter, Alternator
- installation is reverse of removal.
Tightening torques Belt tensloner to engine block
M8 (8.8 grade) 22
Nm (16 ft-ib)
Fan clutch to coolant pump
with BMW special tool 11
5 040 30 Nm (22
ft-lb)
without BMW special tool
11 5 040 40 Nm
(29 ft-ib)
Pulley to alternator 70
Nm (44 ft-lb)
Terminal 30
(B+) wire to alternator (M8) 13 Nm (10 ft-ib)
Alternator, removing and installing
(M62 engine, air cooled)
A replacement alternator should have the same rating as the
original. Alternator manufacturer and ampere rating are nor-
mally
marked on the alternator housing.
- Disconnect negative (-) battery cable.
CAUTION-
Prior to disconnecting the battery, read the battery discon-
nection cautions
001 General Warnings and Cautions.
- Remove cooling fan and alternator drive belt. See 020 Main-
tenance.
- Pry out trim caps and remove fasteners from plastic cover on
left head. Lift off cover.
Disconnect positive
(+) lead from jump start post (arrow).
Raise car and support in a safe manner.
WARNING-
Make sure the car is stable and well supported at aN times.
Use a professional automotive lift
orjack stands designed for
the purpose.
A floorjack is not adequate support.

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121-17
Bauery, Starter, Alternator
- Remove engine splash shield from underneath car.
Working underneath car at rear of alternator, loosen alterna-
tor air cooling duct clamp
(arrow) and remove duct.
Remove three alternator mounting fasteners
(arrows)
Pull alternator forward and disconnect wiring from rear of
alternator.
Release clip retaining wiring harness to alternator.
Rotate alternator forward and then up and out of engine com-
partment, using care to not damage radiator.
CAUTIOe
Protect radiator with heavy cardboard or sheet metal.
Installation is reverse of removal,
Tightening
torques
Fan clutch to coolant pump
with BMW special tool
11 5 040 30
Nm (22 ft-lb)
without BMW special tool 11 5 040 40 Nm (29 ft-lb)
Pullev to alternator 70 Nm 144 it-lb) -,
Terminal 30 (Bt) wire to alternator (ME) 13 Nm 110 ft-lb

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121-18
I Battery, Starter, Alternator
Alternator, removing and installing
(M62 TU engine, water cooled)
V-8 models produced after 9/98 are equipped with a water
cooled alternator.
CAUTION-
Allow engine to cool before removing alternator as coolant
will
escape from the alternator water jacket.
- Disconnect negative (-) battery cable
CAUTION- Prior to disconnecting the
battew read the battery discon-
nection cautions given in
001 General Warnings and Cau-
tions.
- Remove radiator cooling fan and fan shroud. See 170 Radi-
ator and Cooling System.
- Drain engine cooling system. See 170 Radiator and Cool-
ing System.
- Remove alternator drive belt. See 020 Maintenance.
- Disconnect battery lead (terminal 30 or B+) and two-pin har-
ness connector from front of alternator.
I < Remove bolts securing alternator to water jacket and remove
aling ring
alternator.
NOTE- If necessary, raise car and remove engine compartment
splash shield to access lower alternator mounting bolts.
The upper coolant hose can also
be removed to assist al-
ternator removal.

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Battery, Starter, Alternator
- Installation is reverse of removal, noting the following:
Replace alternator rubber sealing O-ring.
* Fill and bleed cooling system as described in 170 Radiator
and Cooling System.
Tightening torques
Fan clutch to coolant pump
with
BMW special tool 11 5 040 30 Nm (22 ft-lb)
without
BMW special tool 11 5 040 40 Nm (29 ft-lb)
Terminal 30 (Bc) wire to alternator (ME) 13 Nm (10 ft-lb)
STARTER
Starter troubleshooting
Typical starter wiring terminal identification is shown. Large
wire at terminal
30 (not shown in photo) is direct battery volt-
age. Smaller wire at terminal
50 operates starter solenoid via
ignition switch.
If starter turns engine slowly when ignition is in start position:
Check battery state of charge.
Inspect starter wires, terminals, and ground
connectlons
for good contact. In particular, make sure ground connec-
tions between battery, body and
englne are completely
clean and tight.
If no faults are found, starter may be faulty and should be
replaced.
- If starter fails to operate, check EWS (drive-away protection
system). Try another ignition key.
If no faults can be found,
have the EWS system checked using
BMW scan tool equip-
ment.
Checkclutch pedal operated
starter lock-out switch or gear
position switch (automatic).
NOTE-
* A factory-installed drive-away protection system, also re-
ferred to as
EWS, is used on E39 cars. This system pre-
vents operation of the starter if a specially coded ignition
key is not used.
On cars with automatic transmission, the transmission
gear position switch signals
EWS to prevent the engine
from starting in gear positions other than PARK or NEU-
TRAL.
On cars with manual transmissions, a starter immobiliza-
tion switch
at the clutch pedal is used to prevent the starter
from operating unless the clutch pedal is pushed fully to
the floor.