2001 BMW 525i 20 pin

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I Cvlinder Head Removal and Installation
4 Install secondary chain tensioner on cylinder head (arrows).
Keep tensioner compressed using BMW special tool 11 3
291 or suitable pin.
< Install exhaust camshaft splined sleeve. Confirm that gap in
sleeve splines aligns with corresponding gap in
camshaft
splines (arrows).
Slide splined shaft onto exhaust camshaft. Be sure that locat-
ing tooth of shaft fits into spline gaps of camshaft and splined
sleeve
(arrows).
- Push splined shaft in further to rotate splined sleeve until the
three threaded holes in primary chain sprocket are centered
in the small slots of the splined sleeve.
4 Place intake and exhaust sprockets in BMW special tool 11 6
180. Position spline gap on intake sprocket (arrow) as shown
and place secondary chain on sprockets.

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1 13-64
Cylinder Head Removal and Installation
< Remove upper timing chain cover fasteners (A) and cover
from left cylinder head.
4 Remove fasteners from intake camshaft sprocket (arrows)
on left cylinder head.
- Remove primary timing chain sprocket and suspend timing
chain using mechanics wire to prevent chain from dropping
into lower housing.
Turn crankshaft counterclockwise until
45" mark on crank-
shaft is aligned with boss on front timing chain cover
(arrow).

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1 13-76
Cylinder Head Removal and Installation
Remove fasteners from intake camshaft sprocket (arrows)
on right cylinder head.
- Remove primary timing chain sprocket and suspend timing
chain using mechanics wire to prevent chain from dropping
into lower housing.
Turn crankshaft counterclockwise until
45" mark on crank-
shaft is aligned with boss on front timing chain cover (arrow)
4 Loosen cylinder head bolts in sequence 1-10 as shown (ar-
rows) and discard used head bolts.
- Evaluate cylinder head. See 116 Cylinder head and val-
vetrain.

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/cylinder Head and Valvetrain
Secondary timing chain tensioner locking pin set (6-cylinder)
- 4 Secondary timing chain tensioner locking pin (V-8)
(Tool No. BMW
11 3 310)
4 Adjustable primary timing chain tensioner tool (V-8)
(Tool No. BMW
11 3 390)
4 Camshaft installation tool (V-8)
(Tool No.
BMW 11 3 430)
4 VANOS compressed air fitting
7 (Tool No. BMW 11 3 450)
Adjustable primary timing chain tensioner tool (6-cylinder) (Tool No. BMW
11 4 220)

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Cylinder Head and valvetrain1
Hydraulic lifters, checking and replacing
Self-adjusting hydraulic lifters (A) keep the valve clearances
within a limited working range. Hydraulic lifters are sealed
units and require no maintenance. Section view of camshaft
(6) and valve with conical valve spring (C) shown.
Under some circumstances, such as a cold start, the cam fol-
lowers may emit noise. Hydraulic lifter noise is usually a
high-
pitched tapping or chattering noise. In most instances, this is
considered normal as long as the noise goes away in a few
minutes (maximum
20 minutes). If the noise does not go
away, either the lifter is faulty or the oil pressure to the lifter is
low. Hydraulic lifter replacement requires that the camshaft
first be removed.
NOTE-
Before checking hydraulic lifters, male sure engine oil is
fresh and at the proper level.
Sticky lifters can be the result of
sludge build up in the cylinder head and lifters.
- Run engine until it reaches normal operating temperature.
Shut off engine.
- Working inside luggage compartment, disconnect negative
battery cable.
CAUTION-
Prior to disconnecting battery cable, read the baltery dls-
connection cautions given In 001 General Cautions and
Warnings.
Disconnecting the battery may erase fault
code(s)
stored in control module memory Check for fault codes
4 Remove left and right interior ventilation duct (left side
shown):
Release plastic locking tab
(A) or release loclting tabs on
top of duct (later models).
Rotate duct counterclockwise to
unloclt from bulithead and
remove (arrow).

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Cylinder Head and Valvetrain
&cylinder models: remove plastic top
- Pry out caps (arrows).
- Remove fasteners and covers. covers:
4 V-8 models: remove plastic top
covers:
Press down on locking pins
(arrows) to release locks and
remove top cover.
Pry out caps
(A) from covers.
Remove fasteners and covers.
4 Lift metal latch on coil harness connectors and disconnect
harness connectors from coils. 6-cylinder shown,
V-8 similar.
- Remove coil grounding straps.
NOTE-
Make note of ground wire at mounting studs arrangement
during removal.
- -- -
-

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116-18
Cylinder Head and Valvetrain
4 Install camshaft carriers with hydraulic lifters into cylinder
head. Note marks on carriers:
(E) for intake side and (A) for
exhaust side.
4 Center camshaft carrier on pins (arrows) at bearing posi-
tions
2 and 7.
4 Install camshafts with number 1 cylinder camshaft lobes fac-
ing each other (arrows).
CAUTION-
A minimum waiting time is required for the hydraulic lifters to
'bleed down" after installing the camshafts into the cylinder
head, before bringing the pistons to TDC. When the cam-
shafts are removed, the hydraulic
lifers can expand. This ex-
pansion can cause increased valve lift when the camshafts
are bolted down, possibly resulting in piston interference.
Camshaft Installation waiting
times
68" F (20" C) or above 4 minutes
50-68' F (1 0-20°C) 11 minutes
32-50" F (0-1 0" C) 30 minutes

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/Cylinder Head and Valvetrain
Press down on secondary chain tensionerand loclc into place
using
BMW special tool 11 3 292, or a thin drift or pin.
4 Remove exhaust camshaft impulse wheel mounting nuts
(arrows). Remove impulse wheel (A).
< Remove spring plate (A).
4 Remove intake camshaft sprocket mounting nuts (arrows)
and remove spring plate (labelled
FRONT).