1997 BMW 525i ECO

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1 Maintenance
NOTE-
Castrol supplies the mineral and synthetic oil recommend-
ed by
BMW
BMW High Performance synthetic oil may be used in all
E39 models, regardless of year.
The use of engine oil additives is not recommended when
using BMW High
Performance synthetic engine oil.
* BMW is constantly upgrading recommendedmaintenance
procedures and requirements. The information contained
here is as accurate as possible at the time ofpublication. If
there is any doubt about what procedures apply to a spe-
cific
model or model year, or what intervals should be fol-
lowed, remember that an authorized BMW dealer has the
latest information on factory-recommended maintenance.
CAUTIOIG
In the case of cars that accumulate very low mileage per
yea/; BMW recommends that the engine oil should be
changed once
a year at a minimum, regardless of whether
mineral or synthetic based oil is used.
In the interest of engine longevity, use half
tlie recom-
mended engine oil change interval.
Engine oil, checking level
4 Engine oil level is checked with a dipstick (arrow) in the
engine block (6-cylinder oil dipstick shown,
V-8 dipstick is
similar).
- Check oil level with car on level surface, after engine has
been stopped for at least a few minutes.
- Check level by pulling out dipstick and wiping it clean
Reinsert it all the way and withdraw it again.

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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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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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Maintenance
- To remove battery corrosion:
Disconnect battery cables. Disconnect negative (-)cable
first.
* Remove battery from trunk
Clean terminal posts and cable clamps with a wire brush.
Clean main chassis ground terminal next to battery.
Corrosion can be washed away with a
baking soda and
water solution that will neutralize acid.
Reinstall battery and reconnect cable clamps, positive
(+)
cable first.
Lightly coat outside of terminals, hold down screws, and
clamps with petroleum jelly, grease, or a commercial
battery terminal corrosion inhibitor.
WARNING
-
Battery acid is extremely dangerous. Take care to keep it
from contacting eyes, skin, or clothing. Wear eye protection.
Extinguish all
smolihg materials and do not work near any
oaen flames.
CAUTION-
Prior to disconnecting the batteg read the battery discon-
nection cautions given in
001 General Cautions and
Warnings.
NOTE-
The original equipment battery in E39 models is mainte-
nance free. The original electrolyte will normally last the
entire service life of the battery under moderate climate con-
ditions.
Battery electrolyte should be maintained at the correct level
just above the battery plates and theirseparators. The correct
level is approximately
5 mm ('14 in.) above the top of battery
plates or to the top of the indicator
marks (if applicable). The
battery plates and the indicator marks can be seen once the
fillercaps are removed.
if theelectrolyte level is low, replenish
it by adding distilled water only.
4 The original equipment BMW battery is equipped with a
built-in hydrometer "magic eye"
(arrow). Battery condition is
determined by the color of the eye:
Green: Adequate charge
* Black: Inadequate charge, recharge
Yellow: Defective battery, replace
Batteries are rated by ampere hours (Ah), the number of
hours a specific current drain can be sustained before com-
plete discharge, or by cold cranking amps (CCA), the number
of amps available to crank the engine in cold weather
condi-

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020-24
Maintenance
tions. In general, replacement batteries should always be
rated equal or higher than the original battery.
The battery is held in place by a single hand screw and plate.
A secure battery hold-down is important in order to prevent
vibrations and road shoclt from damaging the battery.
CAUTION-
Prior to disconnecting the baitem read the battery discon-
nection cautions given in
001 General Cautions and
Warnings.
NOTE-
Always disconnect the negative (-) cable first, and connect
it last. While changing the battery, clean away any corro-
sion in or around the battery tray
More battery and charging system information is in 121
Battery, Alternator, Starter.
Brake fluid, replacing
Brake fluid absorbs moisture easily, and moisture in the fluid
affects bralte performance and reliability. This is why
BMW
strictly recommends replacing the bralte fluid every two
years. When replacing or adding bralte fluid, use only new
fluid from previously unopened containers. Do not use brake
fluid that has been bled from the system, even
if it is brand
new. Use only DOT
4 brake fluid.
NOTE-
See 340 Brakes for brake fluid flushing procedures.
Brake pad 1 rotor wear, checking
Disc brakes are fitted at all four wheels. Although the brakes
are equipped with a brake pad warning system, the system
only monitors one wheel per axle. Pad thickness should be
checked whenever wheels are off or brake
worlt is being
done.
4 Disc brake pad wear can be checked through opening in
caliper:
Measure distance
(A) of brake pad "eai' to bralte rotor.
See
340 Brakes. Compare to specification below.

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020-26
Maintenance
NOTE-
The parking brake may lose some of its effectiveness if it is
not used frequently This is due to corrosion build-up on the
parking brake drum. To remove corrosion, apply the parking
brake just until it begins to grip, then pull the lever up one
more stop (click). Drive the car approximately 400 meters
(1,300
ft.) and release the brake. To recheck the adjustment
of the parking brake see
340 Brakes.
Clutch fluid, checking
In cars equipped with manual transmission and clutch, the hy-
draulic clutch and the brake system share the same reservoir
and the same bralte fluid. Clutch fluid level and brake fluid lev-
el are checked at the same time.
NOTE-
* See 340 Brakes for more information.
See
210 Clutch for information on the clutch and the
hydraulic clutch operating system.
Differential oil level, checking
The E39 differential is filled with lifetime oil that ordinarily
does not need to be changed.
BMW recommends using only
a specially formulated synthetic gear oil
(SAF-XO) that is
available through an authorized
BM\N dealer parts depart-
ment. For additional information on this lubricant and any
other lubricants that may be compatible, contact an
authorized
BMW dealer service department.
< Check rear differential oil level at filler plug (arrow).
- Check lubricant level with car on a level surface:
Level is correct when fluid just reaches edge of filler hole.
If necessary, top up fluid.
Replace filler plug sealing ring.
Install and tighten oil filler plug when oil level is correct.
NOTE-
Use either a 14 mm or 17 mm Allen socket to remove the
drain plug.
If the car is raised in the air, it should be level when
checking or filling final drive fluid level.
Tightening torque
Filler plug to final drive housing 70 Nrn (52 it-lb)

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020-28
1 Maintenance
- When replacing fuel filter:
Use appropriate hose clamping device to clamp off filter
inlet and outlet hoses to lessen fuel spillage.
Loosen center clamping bracket and hose clamps on
either end of filter.
Note arrow or markings indicating direction of flow on
new filter.
Install new filter using new hose clamps
- Drain fuel filter from inlet side into a container and inspect
drained fuel.
Checlc for rust, moisture and contamination.
I - I < If fuel filter is equipped with fuel pressure regulator:
I 2 / Remove vacuum hose (1)
Pull out locking clip (2).
- Remove fuel pressure regulator (3).
Install pressure regulator in new filter.
Clean thoroughly around the filler connections before
removing them.
After assembly, check filter connections carefully for
I
I lealcs before installing cover.
NOTE- ~-
Additional informarion about the fuel filler assembly is in 160
Fuel Tank and Fuel Pump.
Fuel tank and fuel lines, inspecting
lnspectthe fuel tank, fuel lines, and fuel system fordamage or
lealts. Checlc for fuel lealts in the engine compartment or fuel
odors in the passenger compartment. Check for any evapora-
tive emissions hoses that may have become disconnected,
checking carefully at charcoal canister and evaporative emis-
sions purge system. See
130 Fuel Injection and 160 Fuel
Tankand Fuel Pump for component locations and additional
information.
WARNING-
When checlcing for fuel leal(s, the engine must be cold. A hot
exhaust manifold or exhaust system could cause the fuel to
ignite or explode causing serious personal injury Ventilate
the work area and clean up spilled fuel immediately.