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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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. .- -
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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.-
-6val and Installation -
< Remove intake manifold mounting hardware (arrows).
NOTE-
M52 TU engine shown. M52 and M54 engines are similar.
Liit up manifold just enough to remove positive cables from
starter motor terminal
50 (arrow).
- Remove intake manifold from cylinder head while carefully
checking for electrical connections, tie wraps, and hoses.
CAUTION-
Stuff clean rags into open intake ports to prevent any parts
from falling into the engine intake.
4 Remove fastener (A) and harness connector (B) from
alternator.

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I Engine Removal and Installation
WARNING -
Use extreme caution when draining and disposing of engine
coolant. Coolant is poisonous andlethal to humans andpets.
Pets are attracted to coolant because of its sweet smell and
taste. Seek medical attention immediately if coolant is ingest-
---
Working at rear of intake manifold:
Disconnect brake booster vacuum line (A).
Disconnect fuel tank vent line
(6).
Disconnect hoses (C and D) at coolant manifold
- Remove transmission harness support (E).
- Remove oil filter housing assembly from fender:
- Remove oil filter housing mounting fasteners.
Use stiff wire to secure oil filter housing to engine.
NOTE-
Do not disconnect oil lines from filter housing.
4 Disconnect supply and return fuel lines (where applicable) at
or near fuel rail. Plug open fuel lines.
NOTE-
BMW uses three styles of fuel line connections; a slngle use
clamp, a locking fitting that uses special tool
16 7 050 to re-
lease, and a
quiclc release sleeve (arrows) that disconnects
the line when depressed.
WARNING-
Fuel In fuel line is under pressure (approx. 3 - 5 bar or45 -
75 psi) and may be expelled. Do not smoke or worlc near
heaters or other fire hazards. Keep a fire extinguisher
handy. Before disconnecting fuel hoses, wrap a cloth
around fuel hoses to absorb any lealcing fuel. Catch and
dispose of escaped fuel. Plug all open fuel lines.
. Always unscrew the fuel tank cap to release pressure
in the tank before worlcing on the tank or lines.
< Remove air filter housing and mass air flow sensor:
Disconnect mass air flow sensor (A) and
intalte air temper-
ature sensor
(6) electrical harness connectors.
. Remove air filter housing mounting fastener (arrow).
Loosen intake hose clamp (C).
M62 engine: Remove hose at idle air stabilizer.
Remove air filter housing with mass air flow sensor.
Remove intalte hose from throttle body.

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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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..
Cylinder Head Removal and Installation 1
< Remove intake throttle valve and ASC throttle assemblies:
Disconnect ASC throttle cable
(A).
- Remove ASC throttle housing mounting fasteners (B).
NOTE-
It is not necessary to disconnect coolant hoses (C) 01
bowden cables (D).
Remove intake throttle housing mounting hardware, pull
throttle housing off
intake manifold, and set aside.
- Working under intake manifold, disconnect the following:
Engine oil dipstick tube support.
Oil separator return line from dipstick tube.
Intake air temperature sensor electrical harness connector
(underside of intake manifold near throttle body).
* Fuel tank vent line and electrical harness at canister vent
valve.
Remove lower intake manifold supports (arrows).
- Disconnect coolant line retaining bracket at cylinder block.
4 Remove manifold mounting hardware (arrows).
- Remove intake manifold from cylinder head while carefully
checking for electrical connections or hoses.
NOTE-
Fuel rail is removed with intake manifold,
CAUTIOI\C
Stuff clean rags into open intake ports to prevent any parts
from falling into
Nie engine intake.
- Drain cooling system (engine block and radiator), then re-
move radiator cooling fan and fan shroud. See
170 Radiator
and Cooling System.
- Disconnect coolant hoses from thermostat housing.

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Cylinder Head Removal -- and lnstallati~i
4 Cylinder head bolt loosening sequence.
- Using BMW special tool 11 2 250 or an equivalent tool, loos-
en cylinder head bolts in sequence. Discard head bolts.
- Separate the cylinder head from the block and remove head.
Evaluate head as described in
116 Cylinder Head and Val-
vetrain.
Cylinder head, installing, M52 engine
If the camshafts were removed and installed while the cylin-
der head was off, a minimum waiting time is required after in-
stalling the camshafts. When the camshafts are removed, the
hydraulic lifters can expand. This expansion can cause in-
creased valve lift when the camshafts are bolted down, result-
ing in open valves.
Camshaft installation waiting times
68" F (20" C) and higher 4 minutes
50.68' F (1 0-20" C) 11 minutes
32-50' F (0-1 0" C) 30 minutes
- Clean cylinder head and gasket surfaces of cylinder block
and all timing chain covers.
CAUTION-
Do not use a metal scraper or wire brush to clean the alumi-
num cylinder head orpistons. If necessary, use a hard wood-
en orplastic scraper. Also available are abrasive discs to be
used in conjunction with an electric drill. Be sure to use the
correct disc for the type of metal being cleaned.
- Remove all debris and fluids from bolt holes and clean with a
thread chaser.
- Check gasket surface of cylinder head and cylinder block for
warpage using a straight edge.
NOTE-
If the cylinder head has been machined, a special 0.3 mm
thicker gasket should be installed. The thicker
gasket is avail-
able from an authorized
BMW dealer.

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I Cylinder Head Removal and Installation
4 Check that two locating dowels are correctly positioned in
block and are not damaged.
- Apply permanently elastic sealing compound Three Bond
1209 8 to joints where cylinder block joins timing case cover.
- Place new cylinder head gasket on cylinder block.
NOTE-
The word "OBEN" or 'TOP': printed on the gasket, should
face up. The cylinder head
gasket will fit correctly in only one
orientation.
- With camshafts locked in TDC oosition with BMW soecial
tools as described during cylinder head removal,
seicylinder
head in position, guiding primary chain through cylinder head
opening.
NOTE-
* The camshafts must be locl(ed in the TDC position at the
rear of the cylinder head with
BMW special tool I1 3 240
before installing the cylinder head.
Make sure the
cranksha% which had been rotated approx-
imately
30" opposite the direction of engine rotation, is still
in that position before lowering the cylinder head into posi-
tion.
- Lightly lubricate new cylinder head bolts. Loosely install bolts
and their washers, then thread them in until they are finger
tight.
NOTE-
. Torx-type cylinder head bolts should not be reused. They
are stretch-type bolts and must always be replaced when-
ever loosened.
Check that all washers for the cylinder head bolts are in
place before installing the bolts. Some of the washers may
be
stalced to the cylinder head.
CAUTIOI\C
Cylinder head bolts for a cast iron engine block are different
length and require different tightening torque than bolts for an
aluminum cylinder bloclc engines
(95 rnm versus 110 rnm
bolts).
- Install cylinder head-to-lower timing chain cover bolts finger
tight.
< Tighten cylinder head bolts in correct sequence to initial
torque value.