2001 BMW 525i Valve

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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 Installation c
q Remove secondary air inject~on check valve (arrow).
4 Remove cylinder head top cover:
Remove plastic trim caps (arrows).
Remove engine oil filler cap.
Remove cover hold down fasteners and lift off cover.
4 Remove ignition coils:
Disconnect ignition coil harness connectors.
. Remove coil mounting fasteners.
Remove coils.
Remove ground straps.
NOTE-
Make note of ground wire at mounting studs arrangement
during removal.
- Remove sparlc plugs.
- Remove cylinder head cover mounting fasteners and remove
cylinder head cover.
NOTE-
The cylinder head cover mounting bolt insulators and gas-
lets should be reinstalled in their original locations. Make
note of their arrangement during removal.

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113-16
Cylinder Head Removal and Installation
- Remove secondary timing chain and sprockets:
Remove mounting nuts from front of intake camshaft
sprocket. Remove and label shim.
CAUTION-
Hold the camshaft stationary (at hex on camshaft) when loos-
ening or tightening sprocket mounting fasteners.
Remove mounting nuts from front of exhaust camshaft
sprocket and remove and label thrust washer.
NOTE-
Where applicable, make note of thrust washerpositions. The
thicker
(0.4 mm) washer is mounted outermost.
- Remove secondary sprockets together with camshaft tim-
ing chain from front of camshafts.
CAUTION-
The camshafts must be locledin the TDCposition using the
special service tool as described earlier: The arrows on the
sprockets should not be used to accurately set the engine to
TDC. The tool holds the camshafts parallel to each other and
NOTE-
Do not remove the sprocl parts are being replaced. Wire tie each sprocket to the chain
to
Iceep the sproclefs timed to each other:
CAUTIOI\C
The crankshaft must not be allowed to rotate once the cam-
shaft timing chain is removed. The pistons can
contact the
valves.
Unscrew timing chain guide and remove.
Lift off primary sprocket with chain.
Secure chain with wire to prevent chain from dropping into
lower timing cover.
Unscrew timing case cover to cylinder head bolts (arrows).
NOTE-
Photo shows timing chain guide in place; it should first be re-
moved as described previously.
Remove crankshaft locking tool
(BMW special tool 11 2 300).
Using the crankshaft vibration damper bolt, turn engine op-
posite of normal direction of rotation (counterclocltwise as
viewed from the front) approximately 30". This prevents ac-
cidental contact between valves and pistons during installa-
tion.

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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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Cylinder Head Removal and Installation
NOTE-
BMW special tool 11 4 220 is an adjustable primary chain
tensioner and simulates the function of the hydraulic
tensioner.
- Check that elongated holes in primary sprocket are now cen-
tered to bolt holes in camshaft and chain is free of slack. If
not, reposition sprocket to chain and reinstall.
- lnstall secondary timing chain guide and secondary chain
tensioner. Tighten mounting bolts (tensioner remains locked
down for now using
BMW special tool 11 3 292).
- Install cylinder identification trigger plate to front of intake
camshaft with studs.
- Install spacer to front of intake camshaft.
- Install secondary chain sprockets and chain as an assembly
so that arrows on sprockets are pointing up. Center mounting
holes in sprockets to bolt holes in camshafts.
4 lnstall thrust washers and diaphragm spring to intake cam
sprocket.
I 2hm thrust washer I
- Install shim and torx bolts to exhaust camshaft. Tighten fin-
ger tight; do not torque down.
- Tighten intake sprocket nuts.
CA UTIOG
Hold the camshaft stationary (at hex on camshaft) when loos-
enino or tiahtenino sorocket mounting bolts and studs.
Tightening torque
Intake s~rocket nuts to studs 10 +l Nm (89 +9 in-lb)
- Turn crankshaft approx. 30" in direction of rotation to bring
engine to TDC. Lock crankshaft in TDC position with BMW
special tool
11 2 300.
CAUTION-
The camshafts andcranlshaft must be lockedin the TDCpo-
sition using BMW special tools 11 2 300 and 11 3 240. If the
camshafts and cranl(shaft are not at TDC, the valves can
contact the pistons.

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Cylinder Head Removal and lnstallation
NOTE-
Be Sure the secondary timing chain tensioner is locked down
and the exhaust
camshaif mounting bolts are loose before
proceeding.
- Install VANOS control unit. See VANOS control unit, install-
ing
(M52 engine) in 117 Camshaft Timing Chain.
CAUTION--
Incorrect installation ofthe VANOS control may result in dam-
age to the engine valvefrain.
- Install exhaust manifolds using new gaskets and nuts. Coat
manifold studs with copper paste prior to installing nuts.
Install intake camshaft cover and cylinder
head cover.
Check for correct seating of half-moon seals
(A) in back of
cylinder head cover.
Use a small amount of Three Bond 1209
O or equivalent
sealant at corners
(6) of half-moon cutouts.
Seat gasket and seal corners in front of cylinder head at
VANOS unit.
- Installation of remaining parts is reverse of removal, noting
the following:
Reinstall electrical harness connectors for oil pressure
switch and coolant temperature sensor before installing in-
take manifold.
Refill cooling system as described in 170 Radiator and
Cooling System.
Change engine oil and filter as described in 020 Mainte-
nance.
If necessary, adjust accelerator cable.
Reconnect battery last.
Tightening Torques
VANOS oil line
32 Nm (24
ft-lb)
VANOS solenoid to control unit 30 Nm (22 ft-lb)
Coolant drain plug to cylinder
block 25 Nm (18 ft-lb)
Cylinder head cover to cylinder head
10 Nrn (89 in-lb)
(M6 bolts)
intake manifold to cylinder head 15 Nm (I 1 ft-lb)
Radiator cooling fan to coolant pump
40 Nm (30 ft-lb) - . .
Radiator drain screw to radiator 2.5 Nm (22 in-lbl

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Cylinder Head Removal and Installation 1 --
< Remove complete air filter housing assembly with mass air
flow sensor:
Loosen
intalte duct hose clamp (A) at throttle assembly.
Loosen clamp and remove idle control line from intake duct
(B) and disconnect idle speed control valve electrical har-
ness connector.
Disconnect electrical harness connector
(C) from mass air
flow sensor.
Remove air filter housing mounting screw
(D).
Disconnect vent tube (E).
. Loosen air intalte duct clamp (F).
Carefully lifl air filter housing, mass air flow sensor, and in-
take duct hose out of engine bay.
4 Disconnect positive battery cable and remove intake rnani-
fold cover:
Remove protective cover from positive (+)jumper post.
Loosen and remove battery lead mounting nut (A).
Remove lead and push down through intake manifold.
* Remove trim covers (arrows) from fuel injector cover.
Remove cover hold down fasteners and lifl off cover.
4 Worlting above engine, disconnect the following:
Vent line from cylinder head cover. To remove, pinch clips
(arrows).
Electrical harness connector from VANOS solenoid valve
(A).
- Remove oxygen sensors and exhaust manifolds. See 180
Exhaust System.
CAUTION-
Remove oxygen sensors before removing exhaust mani-
fold to prevent damage.
Label oxygen sensor harness connectors so that they
can be reassembled correctly Do not interchange con-
nectors.
NOTE-
Front exhaust manifold must be removed before rear
manifold.

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Cylinder Head Removal and Installation
- Working at side of intake manifold near left strut tower, dis-
connect intake manifold resonance valve electrical harness
connector.
4 Disconnect fuel injector electrical harness connectors from
injectors.
- Use small screwdriver to pry out wire lock clip on fuel injec-
tor
1 connector.
Repeat for remaining injectors.
Release harness conduit fasteners from injector rail.
- Disconnect intake air temperature sensor electrical har-
ness connection (between intake runners for cylinders
3
and 4).
Lift off connector assembly and lay aside.
4 Where applicable, remove schraeder valve cap (arrow) from
fuel
ra~l. Using a tire chuck, blow fuel back through feed line
using a brief burst of compressed air (maximum of
3 bar or
43.5 psi).
WARNING-
Fuel is underpressure (approx. 3 - 5 bar or 45 - 75psi) and
may be expelled. Do not smoke or
work near heaters or
other fire hazards. Keep a fire extinguisher handy Before
d~sconnecting fuel hoses, wrap a cloth around fuel hoses
to absorb any leaking fuel. Catch and
dfspose of escaped
fuel. Plug all open fuel lines.
Always unscrew the fuel tank cap to release pressure
I in the tank before working on the tank or lines.
Disconnect manifold vacuum line (arrow)
Raise car and support in a safe manner,
CAUTION-
Make sure the car is stable and well supported at all times.
Use a professional automotive lift
orjack stands designed for
the purpose. A
floorjack is not adequate support.
Remove protective engine splash guard from below engine.