1998 BMW 525i belt

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I Camshaft Timing Chain
Mark 0" location on socket (arrow). Tighten hub bolt in four
stages.
Tightening torque Vibration damper
hub to cranlrshaft
Stage 1 100 Nm (74 it-lb)
Stage
2 60" Torque angle
Stage
3 60" Torque angle
Stage
4 30" Torque angle
- install vibration damper and mounting bolts
NOTE-
Male sure to align vibration damper with locating dowel pin
in hub.
Tightening torque Vibration damper to
cranltshait hub (ME) 22 Nm (16 ft-lb)
- Install drive belts. See 020 Maintenance.
- Install cooling fan. See 170 Radiator and Cooling System.
- Replace under engine splash shield, then reconnect nega-
tive battery cable.
!/ANBS CONTROL UNIT AND
TIMING CHAIN (M52 ENGINE)
VANOS control unit, removing (M52 engine)
NOTE-
Special BMW service tools are required to remove and in-
stall the
VANOS control unit. Read the procedure through
before starting the job.
If the camshafts are notproperly timed, the pistons can
contact the valves.
- Disconnect negative (-) cable from battery.
CAUTION-
Disconnecting the battery may erase fault code(s) stored in
control module memory. Prior to disconnecting the
battev,
check for fault codes using special BMW diagnostic equip-
ment.
* Prior to disconnecting the battery, read the battery dis-
connection cautions given in
001 General Cautions
and Warnings.

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Camshaft Timing Chain Timing chains, removing
(M52 engine)
Camshaft timing chain removal on M52 engines requires en-
gine oil pan removal.
Special
BMW sewice tools are needed for timing chain re-
moval and installation procedures. The special tools assure
propertiming of thevalvetrain. Precise marks to
setthe timing
on the camshafts are not provided for reassembly. Read the
procedures through before beginning the job.
NOTE-
If the camshafts are not properly timed, the pistons can con-
tact the valves.
- Remove VANOS control unit. See VANOS control unit, re-
moving (M52 engine).
- Remove radiator cooling fan and shroud. See 170 Radiator
and Cooling System.
- Drain cooling system. See 170 Radiator and Cooling Sys-
tem.
- Remove coolant hoses from thermostat housing and remove
thermostat housing from front of cylinder head.
- Loosen bolts for coolant pump pulley.
- Remove drive belts for alternator and AIC compressor. See
020 Maintenance.
- Remove coolant pump pulley.
Remove drive belt tensioner mounting bolts (arrows) and re-
move tensioner from front of engine.
- Remove engine speed sensor from lower timing chain cover.

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11 7-38
[Camshaft Timing Chain
4 Disconnect electrical harness connector (A), oil line fitting
(B), and cranltcase vent tube (squeeze at arrows).
NOJE-
Oil will drain from VANOS unit fitting. Use shop rags to keep
oil off drive belts.
- Remove cylinder head cover fasteners, and cover.
4 Remove oil baffle cover from intake camshaft
4 D~sconnect electrical connections from exhaust camshaft po-
sition sensor and VANOS control valve (arrows).
4 Using banjo bolt from VANOS control unit oil line, install test
fitting
(BMW special tool 11 3 450) to VANOS control unit.

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... -.
Camshaft Timing chain1
Timing chains, removing
(M52 TU and M54 engines)
Camshaft timing chain removal requires that the oil pan be re-
moved. See
119 Lubrication System. Also required is re-
moval of the VANOS control
unit and disassembly of the
intake and exhaust camshaft sprocket assemblies as de-
scribed earlier in this repair group.
Special BMW
service tools are needed for timing chain re-
moval and installation. The special tools assure proper timing
of the valvetrain. Precise
marlts to set the timing on the cam:
shafts are not provided for reassembly. Read the procedures
through before beginning the job.
CA
UTION-
If the camshafts are not properly timed, the pistons can con-
tact the valves.
- D~sconnect negative (-) cable from battery.
CAUTION-
* Disconnecting the battery may erase fault code@) stored in
control module memory. Check for fault codes using spe-
cial
BMW diagnostic equipment.
Prior to disconnecting the battery, read the battery dis-
connection
cautfons given in 001 General Cautions
and
Warninqs.
- Remove VANOS control unit. See VANOS control unit, re-
moving
(M52 TU and M54 engines).
Remove sealing plug from crankcase below starter and se-
cure crankshaft with
BMW special tool ll 2 300.
Drain engine cooling system. See 170 Radiator and Cool-
ing System.
Remove belt driven cooling fan, fan shroud, and thermostat
housing. See
170 Radiator and Cooling System.
Remove drive belts. See
020 Maintenance.
NOTE-
Mark direction of belt rotation if reusing belt.
- Remove water pump pulley fasteners and pulley.
- Drain engine oil and remove oil pan as described in 119
Lubrication System.

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-
Camshaft Timing chain1
4 Remove oil lines from camshaft supports (arrows).
- 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.
- Remove engine drive belts alternator and AlC compressor.
See
020 Maintenance.
4 Remove vibration damper bolts (arrows) and remove
damper.
4 Mount BMW special tool 11 2 450 to crankshaft hub while
aligning damper locator pin with hole (arrow) in special tool.
CAUTION-
Crankshaft center bolt is torqued to 410 Nm (300 ft-lb) use
BMWspecial tool I I 2 450 to secure crankshaft when remov-
ing center bolt.
- Loosen and remove cranltshaff center bolt.

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1 19-1 7
Lubrication System
Disconnect electrical harness connect01
sensor.
. (arrow)
4 Remove lower oil pan bolts (arrows) and pan, oil
level
CAUTION-
If the lowerpan does not separate easily from upperpan, a
few taps with a rubber mallet should break it free. Do not pry
the oil pan loose.
Remove
NC drive belt tensioner.
Remove adjustment bolt
(B).
Remove retaining bolt (A) and remove tensioner from oil
pan.
- Remove power steering pump from engine block, leaving hy-
draulic lines connected. Suspend from chassis using stiff
wire. See
320 Steering and Wheel Alignment.

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Lubr~cat~on System r- -
Working at lower rear of engine, remove oil pan retaining
bolts
(arrows).
- If necessary, remove oil cooler bracket from oil pan.
- Remove remaining oil pan bolts. Slide upper section of oil
pan forward to remove.
- Installation is reverse of removal, noting the following:
Clean sealing surfaces of debris.
- Coat joints with Three Bond 1209 O sealant.
Use new gaskets.
Install all oil pan bolts first, installing bolts at transmission
end without preload.
Tighten oil pan bolts at front end, then tighten bolts at rear
of engine.
Be sure to reinstall all oil
pump fasteners, including the
sprocl - After adding engine oil, start and run engine. Raise engine
speed to
2,500 rpm until oil pressure warning light goes out
(about
5 seconds).
Tightening torques
AIC drive belt tensloner
M6 10 Nm (7.5 it-lb)
M8 24 Nm (18 ft-lb)
Front axle
subframe to chassis
(Use new fasteners) 77 Nm (57 ft-lb)
Oil drain
line to upper oil pan 30 Nm (22 ft-lb)
Oil pump to crankcase 34 Nm (25 ft-lb)
Oil pan fasteners
(upperllower)
M6 8.8 10 Nm (7.5 ft-lb)
M6 10.9 (replace)
I2 Nm (9 ft-lb)
M8 8.8 22 Nm (16 ft-lb)
Steering column universal joint to
steering box (replace) 19 Nm (14 ft-lb)
Oil pressure warning switch, replacing
(&cylinder and V-8)
- In all models, the oil pressure warning switch is located at the
base of the oil filter housing.

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Battery, Starter, ~lternatorl
@ TO fuse & relay panel Battery Safety Terminal
A Battery Safety Terminal (BST) controlled by the Multiple
Restraint System (MRS) control unit was introduced for mod-
el year 1998
vehicles. The system will disconnect electrical
power to the engine compartment
in the event of a significant
impact. The MRS system fires an encapsulated pyrotechnic
device
in the positive (+) battery terminal that disconnects
power to the engine compartment, but maintains power to
the exterior lights and interior of the vehicle.
point
002125~1
Table a. Battery, alternator and starter troubleshooting
1-
/Starter motor or solenoid faulty. l~est starter.
Symptom
Engine does not crank
Engine cranks slowly or
not at all, solenoid
clicits
when starter is operated.
I I
Battery will not stay IShort circuit draining battery. l~est for excessive current drain with everything
Probable cause
Fault
in immobilizer system (EWS)
-Clean Battery cables loose, dirty or corroded.
Battery discharged.
Battery to body ground cable in trunk
loose,
dirty or corroded
Poor connection at starter motor terminal
30.
Corrective action
Try another ignition key. If problem persists, contact
your authorized BMW dealer.
or replace cables. See 020
~aintenance.
Charge battery and test. Replace if necessary.
inspect ground cable. Clean, tighten or replace if
necessary.
Checlc connections, test for voltage at starter. Test for
voltage at neutral safety or clutch
interloclc switch.
charged more than a few
days.
I~atter~ faulty. /Test battery and replace if necessary.
Short driving trips and high electrical drain
on
charging system does not allow battery to
recharge.
. I
I Battery cables loose, dirty or corroded. Iclean or replace cables. See 020 Maintenance.
Evaluate driving
style. Where possible, reduce
electrical
consumption when malting short trips.
Drive
belt@) loose, worn or damaged.
IAlternator or voltage regulator faulty. /Test alternator and voltage regulator.
Inspect
or replace ribbed
belt@). See 020
Maintenance.