1998 BMW 525i maintenance

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020-1 4
Maintenance
- When oil flow has diminished to an occasional drip, reinstall
drain plug with a new metal sealing washer and torque plug.
Tightening torque Engine oil drain plug to oil pan
25 Nrn (1.8 ft-lb)
6-cylinder oil filter assembly
r------ 1
< Working at oil filter housing (1):
Lubricate and install new oil filter O-rings (3, 4).
Install a new filter cartridge (5).
lnstall and tighten housing cover (2).
6-cylinder oil filter assembly shown, V-8 is similar.
Tightening torque Cover to oil filter housing
25 Nm (1.8 it-lb)
- Refill crankcase with oil. Approximate oil capacity is listed in
Tabled. Engine oil with filter change. Use dipstick to
check correct oil level.
- Start engine and check that oil pressure warning light
immediately goes out.
- Allow engine to run fora few minutes to circulate new oil, then
check for leaks at drain plug and oil filter. Stop engine and re-
check oil level
The section describes other routine maintenance done in the
engine compartment. Information on engine oil service is
giv-
enkar~ier inthis group.
For these procedures, it is not necessary for the car to be
raised and supported off the ground.
Accelerator and linkage
The accelerator and linkage at the throttle housing should be
lubricated periodically. Use ageneral purposeoil on the joints
and bearings of the linkage. Use a multipurpose grease on
the bearing points of the throttle plate.
Air filter, replacing
The specified replacement intervals forthe air filter are based
on normal use. If the car is operated primarily in dusty
conditions, the air filter should be serviced more frequently.

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Maintenance
< Release mass air flow sensor clips (A).
Release upper air filter housing clips (B).
4 Lift air filter upper housing, and remove filter element.
NOTE-
V-8 engine air filter assembly shown in illustration. 6-cylinder
air filter assembly is similar but located at the left front of the
engine compartment.
- On installation, install O-ring for mass air flow sensor into
retaining clips in air filter upper housing.
- Replace air filter and upper air filter housing, and attach
upper air filter housing clips.
Cooling system, checking
Antifreeze raises the boiling point and lowers the freezing
~oint of the coolant. BMW recommends enaine coolantthat is
a 50 150 mixture of distilled water and ethGene glycol-based
antifreeze.
Routine cooling system maintenance consists of maintaining
the coolant level and inspecting hoses. Because the coolant's
anticorrosion and antifreeze additives gradually lose their ef-
fectiveness, replacement of the coolant every three years is
recommended.
CAUJION-
Use only BMWapprovedphosphate-free antifreeze when
filing the cooling system. Use of antifreeze containing
phosphates is harmful to the cooling system.
4 Float in radiator tank indicates coolant level. Inspect while
coolant is cold.
When upper mark on float is level with top of filler neck,
coolant is at minimum allowable level.
When lower mark on float is level with top of filler neck,
coolant is at maximum level.
Hose connections should be tight and dry. Coolant seepage
nnection indicates either that hose clamp is

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020-1 6
Maintenance
loose, hose is damaged, or connection is dirty or corroded.
Dried coolant has achalky appearance. Hoses should be firm
and springy. Replace any hose that is cracked, has become
soft and limp, or has been contaminated by oil.
4 As a preventive measure, replacement of the cooling system
hoses every four years is recommended. The illustration
shows examples of damage to coolant hoses. Any of these
conditions is cause for replacement (illustration courtesy of
/ Abrasion Damaged Hose Heat Damaged Hose 1 Gates Rubber Company, I~c.).
Engine drive belt, replacing
Drive belts and pulleys transfer power from the engine crank-
shaft to various accessories.
E39 models use two polyribbed
(serpentine) belts:
The outer belt turns the
NC compressor.
0 The inner, longer belt turns the alternator (generator), cool-
ant pump and power steering pump.
Inspect drive belts with the engine off. If the belt shows signs
of wear, cracking, glazing, or missing sections, it should be
replaced
immediately. To reduce the chance of belt failure
while driving, replacement of the belts every four years is
recommended.
WARNING -
Observe care when replacing belts. Personal injury could
result if a tensioner springs back into position uncontrolled.
CA UTIOI\C
Mark drive belt rotation direction if removing and reusing an
old belt.
NOTE-
When belts are replaced with new ones, store the old set in
the trunk for emergency use.
All models, use
BMW special tools 11 5 030 and 11 5 040 to
loosen and remove cooling fan and clutch from coolant
pump.
NOTE-
32 mm cooling fan nut has left-hand threads
If necessary, remove fan cowl from radiator.

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020-1 8
Maintenance
V-8 engine drive belt diagram (NC belt not shown).
NOTE-
Two types of belt tensioners are used on the V-8 engines.
The tensioner shown in this procedure is for cars built up to
8/97. The later style tensioner is similar.
4 V-8 engine tensioner.
Loosen
fasteners(A) to relieve belt tension
- Remove drive belt.
4 When reinstalling belt, check that it is correctly positioned on
belt pulleys.
With bolts
(B and C) finger tight, pretension adjuster by
turning hex counterclocltwise
(arrow) to stop.
Tighten mounting bolts.
NOTE-
On 8/97 and later tensioner, turn hex on tensioner plate to
align lowerplate mounting bolt.

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Maintenance
< Remove NC compressor belt:
Loosen tensioner mounting fasteners (arrows)
Swing tensioner down to remove belt.
4 To reinstall compressor belt:
Route belt over pulleys.
* Pretension belt by turning adjuster clockwise (arrow) to
stop.
- Tighten tensioner mounting bolts (A).
Tightening torques
Fan clutch to coolant pump (left- hand thread)
with BMW tool
11 5 040
30 Nm (22 ft-lb)
without BMW tool 11 5 040
40 Nm (29 ft-lb)
Tensioner to engine block
8.8 grade
22 Nm (16 ft-lb)
10.9 grade (Ilquid-cooled alternator) 30 Nm (22 ft-lb)
Idle speed
Engine idle speed can change due to a number of factors, in-
cluding normal wear. The idle speed is electronically adaptive
and not adjustable. See
130 Fuel Injection for more informa-
tion.
Catalytic converter and oxygen sensors
OBD II enhanced emission standards require the engine
control module (ECM) to monitor the oxygen content in the
exhaust with oxygen sensors placed before and after the cat-
alytic converter. This allows for tighter control of tail pipe
emissions and also allows the ECM to diagnose converter
problems. If the ECM detects that catalytic converter or oxy-
gen sensor efficiency has degraded past a certain
prepro-
grammed limit, it will turn on the malfunction indicator light
(MIL), and store a diagnostic trouble code (DTC) in the ECM.
See OBD On-Board Diagnostics for more information on
OBD
ll systems.
Replacement of oxygen sensors at the specified intervals
he engine and emission control system will

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Maintenance
continue to operate as designed. Extending the replacement
interval may void the emission control warranty coverage.
See
180 Exhaust System for information on replacing the
oxygen sensors.
Tightening torque
Oxvoen sensor to exhaust
manifold 50 Nrn (37 ft-lb)
NOTE-
A special soclet for replacing the oxygen sensor is available
from most automotive parts stores. The soclet has
a groove
cut down one side to allow the sensor to be installed without
damaging the wire harness.
Power steering fluid, checking level
The power steering system is permanently filled and does not
have a drain. Routinely adding ATF is not required unless the
system is leaking.
4 To check power steering fluid level in fluid reservoir:
Park car on level ground with engine off.
Level is correct
if it is between MlN and MAX marks on
dipstick.
If level is below
MlN mark, add fluid to reservoir to bring
level up.
* Hand-tighten reservoir cap.
Power steering fluid
Dexron
1iiO ATF or equivalent
Spark plugs
E39 models through model year 1998 were equipped with
spark plugs with two electrodes. These are gapped to
0.7 mm
(0.028 in) by the manufacturer and are not adjustable.
Starting with 1999 models, long life spark plugs with
3 or four
electrodes were used. These can be retroactively fitted to
earlier
models. The recommended spark plug replacement
interval
forthese is 100,000 miles.The electrode gap in these
spark plugs is not adjustable.
Spark plug applications
M52 Bosch FBLDCR
M52 TU, M54 Bosch FGR7DQP or NGK BKRBEQUP
M62 to 7/97 Bosch F7LDCR or NGK BKR6EK
M62 from 7/97 Bosch F9LDCR
M62 TU Bosch FGR7DQP or NGK BKRGEQUP

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020-21
Maintenance
Spark plugs, replacing
E39 engines use a coil-over-spark plug configuration, with
one ignition coil above each spark plug. Sparks plugs should
be removed only after the engine has cooled.
Remove engine
cover(s) over ignition coils:
Remove acoustic cover over fuel injectors
I intake
manifold.
6-cylinder engine: Remove oil filler cap.
Remove plastic trim covers (arrows).
Remove cover hold-down bolts. Remove coil
cover(s)
6-cylinder engine: Temporarily reinstall oil filler cap to
keep out contaminants.
Remove ignition coil grounding harnesses (arrows). 6-cylin-
der coils shown,
V-8 engine is similar.
< Remove ignition coils:
Pull up on spring clips to disconnect ignition coil harness
connectors.
Remove coil mounting bolts. Pull coils up and off spark
plugs.
- Remove spark plugs.

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020-22 Maintenance
1
- Installation is reverse of removal, bearing in mind the
following:
Lightly lubricate new
spark plug threads with
copper-based anti-seize compound.
Thread plugs into cylinder head by hand to prevent
cross-threading.
. Be sure to reinstall and tighten coil grounds.
Tightening torque Spark plug
to cylinder head 25 Nm (18 It-lb)
Interior ventilation microfilter, replacing
Two interior ventilation microfilters are used, one on each
side of the engine compartment at the fire wall.
< To replace the microfilter, unclip the wire fastener and
remove the cover.
Lift out the filter, and replace. Left side shown; right is
similar.
Replace cover and clip wire fastener to retain cover.
Battery, checking, cleaning, and replacing
The battery Is located in the right side of the luggage compart-
ment. Simple maintenance of the battery and its terminal
connections will ensure maximum starting periormance,
especially in winter when colder temperatures reduce battery
power.
Battery cables should be tight. The terminals, cable clamps
and battery case should be free of the white deposits that
indicate corrosion and acid salts. Even a thin layer of dust
containing conductive acid salts can cause battery discharge.