1999 BMW 525i Workshop Manual

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I Cylinder Head Removal and Installation I
< Use BMW tool 11 2 110 or torque angle gauge to tighten cyl-
inder head bolts in sequence to stage
2 and 3.
Tightening torques
Cylinder head to cast iron
bloclc
Staoe 1
staie 2
Stage 3
Cyllnder head to aiumlnum block
Stage
1 40 Nm (30 it-lb)
Stage 2 +90°
Staoe 3 -80"
- Tighten cylinder head-to-lower timing chain cover bolts.
Tightening torques
cylinderhead to lower timing chain cover 10 Nm (89 in-lb)
- Inspect secondary chain guide rail and tensioner rail for
grooves caused by chain contact. Replace any part that is
worn.
NOTE-
Inspect timing chain sprocl(ets. Sprockets that have worn
or missing teeth should be replaced.
* If any of the sprockets are being replaced due to wear, the
chain should also be replaced.
If the crankshaft sproclet requir?s replacement, the oil
pump drive sprocket and chain must be removed as de-
scribed under
119 Lubrication System.
The procedure outlined below assumes that the camshafts
and the
cranl(shaft are locledin the TDCposition with special
4 Mount primary timing chain sprocltet to primary chain so that
arrow on sprocket faces up. Mount sprocket to camshaft so
that tapped holes in camshaft are on left side of elongated
holes in sprocltet
Install BMW special tool
1 I 4 220 into primary timing chain
tensioner sleeve. Thread center spindle in finger tight
until
slack is removed from chain.

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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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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.
: is similar

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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.

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11 3-25
Cylinder Head Removal and Installation
4 Working beneath car (on left side under driver seat), remove
fuel filter cover and clamp
off fuel hose(s).
NOTE-
M54 engines use a single fuel line to the non-return fuel rail.
Disconnect fuel lines by pressing in on spring lock (arrows).
CAUTION--
Fuel may be expelled underpressure. 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 leaking fuel. Plug all open fuel lines.
NOJE-
BMW uses various styles of line connections; a one-time
band clamp; a
self-locl(ing connector (that use BMWspecial
tool 16 1 050 to release); and a quick release connector
(above).
4 M52 TU engine: Pull throttle cable out of rubber retainer (A)
and unhook ball end of cable (6) from throttle actuator.
4 Remove fasteners retaining wiring harness at throttle body
and support bracket (arrows).

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. - --
j Cylinder Head Removal and Installation
4 Working at throttle housing, unscrew and disconnect electri-
cal harness plug
(arrow).
4 Disconnect electrical harness connector at fuel tank venting
valve
(A) and vent hose at quick disconnect fitting (arrow).
- Working under intake manifold, disconnect the following:
Engine oil dipstick tube support.
Oil separator return line from dipstick tube.
Knock sensor harness connector from support.
4 Working underneath car, remove intake manifold support
mounting nut
(arrow), located adjacent to left engine mount.