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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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Maintenance
Suspension, front, inspecting
Inspection of the front suspension and steering includes a
check of all moving parts
forwear and excessive play. Inspect
ball joint and tie-rod rubber seals and boots for cracks
ortears
that could allow the entry of dirt, water, and other
contaminants. See
310 Front Suspension.
Suspension, rear, inspecting
Differential and rear drive axle service consists of checking
and changing the gear oil, inspecting for leaks, and checking
the drive axle
CV joint boots for damage.
The areas where
lealts are most likely to occurare around the
drive shaft and drive axle mounting flanges. For more infor-
mation on identifying oil leaks and theircauses, see
330 Rear
Suspension and
331 Final Drive.
Tires, checking inflation pressure
Correct tire pressures are important to handling and stability,
fuel economy, and tire wear. Tire pressures change with tem-
perature. Pressures should be
checked oRen during season-
al temperature changes. Correct inflation pressures can be
found on the driver's door pillar and in the owner's manual.
Note that tire pressures should be higher when the car is
more heavily loaded.
WARNING-
Do not inflate any tire to a pressure higher than the tire's max-
imum inflation pressure listedon the sidewall. Use care when
adding air to warm tires. Warm tire pressures can increase as
much as
4 psi (0.3 bar) over their coldpressures.
Tires, rotating
BMW does not recommend tire rotation. Due to the car's sus-
pension design, the front tires begin to wear first at the outer
shoulder and the reartires begin to wearfirst at the middle of
the tread or inner shoulder. Rotating the tires may adversely
affect road handling and tire grip.
Transmission service, automatic
The automatic transmissions installed in E39 models are
filled with special automatic transmission fluid. The transmis-
sion lubricant type can be found on the "type-plate" on the
side of the transmission. The recommended lubricants are
listed earlier in this repair group. See Fluids and lubricants.
If in doubt, consult an authorized BMW dealer for alternate

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020-30
Maintenance
fluid use and the most-up-to-date information regarding
transmission operating fluids.
The automatic transmission is not equipped with a dipstick.
Therefore, checking the ATF level is an involved procedure
which includes measuring and maintaining a specified ATF
temperature during the checking procedure.
For more complete
ATF service information, including
checking
ATF level and ATF filter replacement procedures,
see
240 Automatic Transmission.
Transmission service, manual
Manual transmission service consists of inspecting for leaks
and checking the fluid. Evidence of transmission leaks is
like-
ly to be seen around the driveshaft mounting flange and at the
bottom of the bellhousing.
NOTE-
For more information on identifying oil
leaks and their
causes, see 230 Manual Transmission and210 Clutch.
Transmission fluid, checking and filling
(manual transmission)
Tne manual transmss'on inslalleo 'n rne E39 models s f;lled
with a special liierime iluid (ivlTF-LT-I). oi. ordinarily
does
not need to be changed.
< Check manual transmission oil level at transmission filler plug
(A). Make sure car is on level surface.
NOTE- Transmission fluid level
checking and replacement
procedures are covered in 230 Manual Transmission.
Wheels, aligning
BMW recommends checking the front and rear alignment
once a year and whenever new tires are installed.
NOTE-
See 320 Steering and Wheel Alignment for a more detailed
discussion of alignment requirements and specifications.

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. .- -
I Engine Removal and Installation I
4 Where applicable, remove schraedervalve cap (arrow) from
air connection on fuel rail. Using a tire chuck, blow fuel back
through feed line using a brief burst of compressed air
(rnax-
imum of 3 bar or 43.5 psi).
WARNING -
Fuel in fuel line is under pressure (approx. 3 - 5 bar or 45 -
75psi) andmay be expelled underpressure. Do not smoke
or work near heaters or other fire hazards. Keep a fire ex-
tinguisher handy Before disconnecting fuel hoses, wrap
a
cloth around fuel hoses to absorb any leaking fuel. Catch
and dispose of escaped fuel. Plug all open fuel lines.
Alwavs unscrew the Fuel tank cao to release
oressure
I in the tank before working on the tank or lines. I
- Raise car and support in a safe manner.
WARNING-
Male sure the car is stable and we/ supported at all times.
Use a professional automotive lift orjackstands designed for
the purpose. A floor jack is not adequate support
- Working underneath car, remove protective engine splash
guard.
4 Disconnect fuel lines by sliding locking collar in (arrows) and
pulling line apart.

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11 3-2
Cylinder Head Removal and Installation
This group covers cylinder head removal and installation as
well as cylinder
headlvalve diagnostic procedures.
In the procedures in this repair group, engines are referred to
by engine code. If necessary, see
100 Engine-General for
engine code and application information.
The information given in this repair group assumes that the
engine is installed in the engine bay. On the
6-cylinder en-
gines, the VANOS control unit must be removed in orderto re-
move the cylinder head from the engine block. On
M52TU
and M54 engines, camshafts must be removed from the cylin-
der head before the head is removed.
The cylinder head removal and installation procedures for the
M62 V-8 are also included, butthe proceduresforthe M62TU
V-8 with VANOS are not provided.
For cylinder head and valvetrain reconditioning information,
see
116 Cylinder Head and Valvetrain.
For specific repair procedures, refer to the appropriate repair
group:
020 Maintenance
116 Cylinder Head and Valvetrain
117 Camshaft Timing Chain
170 Radiator and Cooling System
610 Component locations
NOTE-
If a head gasket problem is suspected, a compression test or
leak-down test will usually detect the fault See Diagnostic
Testing later
in this group.
Special tools
Special BMW service tools are required to properly remove
and install the cylinder head on engines covered by this man-
ual. The special tools are used to time the valvetrain to the
crankshaft, and to remove the VANOS control unit, the cam-
shafts and the
Tom (El2) head bolts. Read the entire proce-
dure through before beginning the job.

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113-8
[cylinder Head Removal and Installation 1
Cylinder leak-down test
The most conclusive diagnosis of low compression symp-
toms requires a cylinder leak-down test. Using a special
tester and compressed air, each cylinder, in turn, is pressur-
ized. The rate at which the air leaks out of the cylinder, as well
as where the air leaks out, can accurately pinpoint the magni-
tude and location of the leakage.
Before attempting any repair that requires major engine dis-
assembly, use a leak-down test to confirm low compression.
~YL~NDER HEAD REMOVAL AND
~NSTALLATION (M52 ENGINE)
WARNING-
Due to rislc of personal fnjur~: be sure the engine is cold be-
fore beginning the removal procedure.
Cylinder head removal and installation is a time consuming
repair procedure requiring multiple special
service tools.
Read the entire procedure before beginning the repair.
This procedure includes the following steps:
Cylinder head, removing,
M52 engine
Cylinder head, installing,
M52 engine
Cylinder head, removing, M52 engine
- Disconnect negative (-) cable from battery in luggage com-
partment.
CAUTION-
Prior to disconnecting the battea read the battery discon-
nection cautions in 001 General Cautions and Warnings.
-

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113-10
Cylinder Head Removal and Installation
4 Working above engine, disconnect the following:
Vent line from cylinder head cover
(A).
. Oxygen sensor connectors (B).
Electrical harness connector from VANOS solenoid
valve
(C).
Electrical harness connectors at throttle valve position
switch
(D), ASC valve position switch (E), fuel injector har-
ness
(F) and vent valve (G).
CAUTION-
Be sure to mark oxygen sensor harness connectors so that
they can be reassembled correctly Do not interchange con-
nectors.
4 Where applicable, remove schraeder valve cap (arrow) from
air connection on fuel rail. Using a tire chuck, blow fuel back
through feed line using a brief burst of compressed air (max-
imum of
3 bar or 43.5 psi).
WARNING-
. Fuel in fuel line is underpressure (approx. 3 - 5 bar or 45 -
75 psi) and may be expelled. Do not smoke or work near
heaters or other fire hazards. Keep a fire extinguisher
handy Before disconnecting fuel hoses, wrap a cloth
around fuel hoses to absorb any leaking fuel. Catch and
dispose of escaped fuel. Plug open fuel lines.
- Always unscrew the fuel rank cap ro release pressure
;n the tank before working on the tank or lines.
Disconnect fuel lines by sliding locking collar in (arrows) and
pulling lines apart.
NOTE-
BMW uses three styles of fuel line connections; a one-time
use
clamp; a locking fitting that uses BMWspecial tool 16 1
050 to release; and a quick release sleeve (above) that dis-
connects the line when depressed.

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1 13-22
Cylinder Head Removal and Installation
CYLINDER HEAD REMOVAL AND
~NSTALLATION (M52 TU AND N154
ENGINES)
WARNING -
Due to risk ofpersonal injur)c be sure the engine is cold be-
fore
beqinning the removal procedure.
Cylinder head removal and installation is a time consuming
repair procedure requiring multiple special service tools.
Read the entire procedure before beginning the repair.
This topic includes the following procedures:
* Cylinder head, removing, M52 TU and M54 engines
Cylinder head, installing,
M52 TU and M54 engines
Cylinder head, removing,
M52 TU and M54 engines
Allow engine to cool before beginning this procedure.
- Disconnect negative (-) cable from battery.
CAUTION-
Prior to disconnecting the battery, read the battery discon-
nection cautions in
001 General Cautions and Warnings.
4 Remove left and right interior ventilation ducts (left side
shown):
Release ventilation filter cover latch
(A) and remove cover.
Release plastic locking tab
(6) or release locking tabs on
top of duct (later models).
= Turn duct counterclocltwise to unlock from bullthead and
remove (arrow).
Disconnect electrical harness from hood switch (C).
Release spring lock fastener
(D).
- Slide filter housing away from inner fender to remove.
Removal of right side ventilation
dud
Remove rear bulkhead panel:
Lift off rubber sealing
gasket (arrow)
- Remove 3 mounting clips (A).
Remove 4 retaining screws (6).
Lift off panel.
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