2001 BMW 525i Valve

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110-8
1 Engine Removal and Installation
4 M52 TU, M54 engine: Remove fasteners (arrows) retaining
wiring harness conduit to throttle body.
4 M52 TU, M54 engine: Working at throttle housing, rotate har-
ness plug (arrow) counterclockwise and remove.
4 M52 TU, M54 engine: Disconnect electrical harness connec-
tor at idle speed control valve (arrow), directly above throttle
valve.

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Engine Removal and lnstallationl
M52 TU, M54 engine: Disconnect electrical harness connec-
tor at fuel tank venting valve
(A). Disconnect vent hose at fit-
ting (arrow).
- Working under intake manifold, disconnect the following:
Engine oil dipstick tube support.
Oil separator return line from
dipsticlc tube.
Intake air temperature sensorelectrical harness connector
(underside of intake manifold near throttle body).
M52 TU, M54 engine: Resonance valve electrical harness
connector.
M52 engine: Fuel tank vent line and harness.
< Working underneath car, remove lower intalte manifold sup-
port mounting bolts (arrows).
4 M52 TU. M54 engine: Remove fuel rail mounting bolts
(arrows):
Carefully pry fuel rail off manifold.
Separate fuel line support bracket at rear of intake
manifold.
NOTE-
* M52 TU engine shown. M54 engine is similar.
M52 engine: Fuel rail is removed with intalte manifold.

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Engine Removal and Installation
4 Working at E-box at right rear of engine compartment:
Disconnect engine electrical harness connectors
(arrows).
Lift off harness looms and lay over engine.
- Remove polyribbed drive belts. Mark direction of rotation if
belts will be reused. See 020 Maintenance.
- Remove exhaust system and transmission from car. See 180
Exhaust System, 230 Manual Transmission or 240 Auto-
matic Transmission.
NOJE-
Detach automatic transmission cooler lines from radiator, re-
move brackets holding lines to side of engine, andstore lines
in a clean environment.
- Remove power steering pump:
If necessary, remove steering pump pulley.
Remove front and rear pump mounting bolts.
Suspend pump from body using stiff wire.
4 Remove A/C compressor mounting bolts (arrows) and AIC
compressor from its mounting bracketwithoutdisconnecting,
distorting, or deforming any refrigerant lines. Suspend from
body using stiff wire.
4 If applicable, remove secondary air pump:
Remove hose at one-way valve
(A).
Remove bolts at support bracket on strut tower (arrows).
- Disconnect electrical harness from bottom of secondary
air pump.
Remove bracket from strut tower.

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110-19
Engine Removal and Installation
M62 engine, remove ASC throttle body.
Disconnect electrical harness from throttle position sensor.
- Disconnect ASC actuator cable (arrow).
. Remove mounting fasteners and remove throttle body.
On front of left side cylinder head, disconnect electrical har-
ness connector
(A), and remove and plug fuel tank vent valve
vacuum line
(0).
Raise car and support in a safe manner.
CAUTION-
Male sure the car is stable and well supported at aN times.
Use a professional automotive
lifi orjackstands designed for
I the ouroose. A floor jack is not adequate support.
Working beneath car:
- Remove engine splash shield.
Remove right and left heat shield from front suspension
subframe.
Working underneath engine compartment, disconnect
ground cable on right side engine mount
(arrow).

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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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. .- . --
Lr -- - - - -- Cylinder Head Removal and Installation I -
- Release pressure at compression gauge valve, then remove
gauge from spark plug hole. Repeat test for each cylinder
and compare results with values given in Table a.
Table a. Compression testing specifications
Minimum compression
6-cylinder
10-1 1 bar (142-156 psi)
V-8 12-14 bar (174-203 psi)
Maximum difference between
cylinders (all engines)
0.5 bar (7 psi)
- Compression readings may be interpreted as follows:
Low compression indicates a poorly sealed combustion
chamber.
0 Relatively even pressures that are below specification nor-
mally indicate worn piston rings
andlor cylinder walls.
Erratic values tend to indicate valve leakage.
Dramatic differences between cylinders are often a sign of
a failed head
gasket, burned valve, or broken piston ring.
- If readings are within specifications, reinstall spark plugs and
ignition coils.
NOTE-
Used spark plugs should be reinstalled in the same cylinder
from which they were removed.
Tightening torque Spark plug to cylinder head 25 Nm
(18 ft-lb)
lanition coils to cylinder head 10 Nm (7.5 ft-lb)
- Remainder of installation is reverse of removal. Be sure to re-
install all wires disconnected during test, especially ground
wires at coils and cylinder head cover (where applicable).
Wet compression test
To further help analyze the source of poorcompression,awet
compression test is the next step.
- Repeat compression test, this time squirt a teaspoon of oil
into each cylinder. The oil will temporarily help seal between
piston rings and cylinder wall, practically eliminating leakage
past rings for a short time.
- If this test yields a higher reading than "dry" compression
test, there is probably leakage between piston rings and
cylinder walls, due either to wear or to broken piston rings.
- Little or no change in compression reading indicates other
leakage, probably from valves.

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11 3-9
Cylinder Head Removal and Installation
< Remove left and right interior ventilation ducts (left 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).
Rotate duct counterclockwise to unlock from bulkhead and
remove (arrow).
Disconnect electrical connector from hood switch
(C).
Release spring lock (D).
Slide filter housing away from inner fender to remove.
Removal of right side ventilation duct is similar.
Remove rear bulkhead panel: Remove rubber sealing
gasket (arrow).
0 Remove 3 mounting clips (A).
Remove
4 retaining screws (6).
Lift out panel.
< Remove complete air filter housing:
Loosen
intake duct hose clamp (A) at throttle assembly.
Loosen clamp and remove idle control hose from
~ntake
duct (6) and disconnect Idle speed control valve electr~cal
harness connector.
Disconnect
electr~cal harness connector (C) from mass alr
flow sensor.
Remove air filter housing mounting screw (D).
Disconnect vent tube
(E).
Loosen air intake duct clamp (F).
Carefully lift air filter housing out of engine bay.
4 Remove positive battery cable and intake manifold cover:
Remove protective cover from positive (+)jumper post (A).
Loosen and remove battery lead mounting nut.
Remove battery lead and push down through intake mani-
fold.
Remove trim caps (arrows) from fuel injector cover.
Remove cover hold down fasteners and lift off cover.

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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.