1998 BMW 540i Camshaft position

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4 With crankshaft at TDC position, remove vibration damper
bolts (arrows) and remove vibration damper.
< Mount crankshaft holding tool (BMW special tool 11 2 150
and
11 2 410) to crankshaft hub. Counter hold crankshaft and
loosen crankshaft hub retaining bolt.
Crankshaft hub retaining bolt is torqued to
410 Nm (300 ft-lb).
Do not use flywheel
locliing tool to hold cranl(shait stationary
to loosen or tighten crankshaft hub center bolt. Use only the
special tools specified, or equivalent hub holding tool.
- Remove crankshaft hub.
- Remove cylinder cover mounting fasteners and remove cyl-
inder head cover.
NOTE-
The cylinder head cover mounting bolt insulators and gas-
lets should be reinstalled in their original positions. Make
note of their arrangement during removal.
- Drain engine oil, remove oil pan. See 119 Lubrication Sys-
tem.
Remove primary timing chain tensioner (arrow).
CAUTION-
Timing chain tensioner is under spring tension. I
- Remove VANOS control unit. See VANOS control unit, re-
moving
(M52 engine).
- Remove fasteners from intake and exhaust camshaft
sprocket.

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1 17-30
I Camshaft Timing Chain
Timing chain, installing
(M52 engine)
CAUTION-
The procedure outlined below assumes that the camshafts
and the crankshaft are
lockedin the TDCposition with BMW
special tools.
- Inspect timing chain and sprocltets and guide rails for wear.
Replace worn parts.
NOTE-
If any of the sprockets are being replaced due to wear, the
chain should also be replaced.
Install primary timing chain
on exhaust camshaft. to crankshait
sprocket and hang
4 Apply a small bead oi silicon sealer (Three Bond 1209 @or
equivalent) to corners where tim~ng cover meets cylinder
head
(arrows).

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Camshaft Timing chain1
Tap locating dowels into cover until they protrude 2 to 3 mm
from sealing surface.
- Using new gaskets, install lower timing chain cover:
Tap cover into position to engage dowels.
Install timing chain cover fasteners and tighten to
5 Nm (44
in-lb).
Drive dowels in flush to front of cover.
. Tighten cover mounting bolts alternately and in stages.
Install cylinder head to timing chain cover fasteners and
tighten.
Tightening torques Lower timing chain cover to block
M7 15 Nm (1 1 ft-lb)
ME 20 Nm (15 it-lb)
- Replace front crankshaft radial seal. See Crankshaft oil
seal, front, replacing
(M52 engine).
Install engine oil pan using
a new gasket. See 119 Lubrica-
tion System.
Mount primary timing chain sprocket to primary
cha~n so that
arrow on sprocket faces up. Mount sprocket to camshafl so
that tapped holes in camshaft are on left side of elongated
holes in sprocket.
4 Install adjustable timing chain tensioner (BMW special tool
11 4 220). Thread tool in finger tight until slack is removed
from chain.
NOTE-
BMW special tool 11 4 220 is an adjustable timing chain ten-
sioner that simulates the function of the hydraulic tensioner.
- Check that elongated holes in primary sprocket are centered
to bolt holes in camshafl and chain is free of slack.
- Install secondary timing chain guide and secondary chain
tensioner. Tighten mounting bolts (tensioner remains
locited
down).
F81.,,l,ryT-iib.l>nii,:oni-Aii Ri"ilti R

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1 17-34
1 Camshaft Timing Chain
DOUBLE VAMOS SYSTEM
(M52 TU AND M54 ENGINES)
Double VANOS system function
The M52TU and M54 6-cylinder engines are equipped with a
Double VANOS system that varies intake and exhaust cam-
shaft timing.
The main components of the Double VANOS system are:
lntalte and exhaust camshafts with helical spline inserts.
Camshaft sprockets with adjustable gears.
VANOS actuators (two position piston housing with
inter-
nallexternal helical spline cup).
Three-way solenoid switching valves.
Camshaft position impulse wheels.
Hall effect camshaft position sensors.
Camshaft position
IS varied based on engine rpm, throttle po-
sition signal, intake air and coolant temperature.

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Camshaft Timing Chain
1 VANOS I 4 When engine is started, camshafts are in deactivated
camshaft
retarded Engine I i oil supply
position:
. lntalte camshaft is held in RETARDED position by oil
pressure.
Exhaust camshaft is held in ADVANCED position by
preload spring and oil pressure.
VANOS
Piston out
ECM Piston in Within 2
- 5
seconds (50 engine revolutions), the ECM begins
monitoring and controlling camshaft positions.
The Double VANOS system allows full variability of camshaft
timing up to the limits of the system. When the ECM detects
that the camshafts are in optimum position, the solenoids are
modulated at approximately 100
- 220 Hz to maintain oil pres-
sure on both sides of the actuator pistons to maintain timing.
In models with DME
MS 43.0 (model year2001 and newer),
the engine control module (ECM) detects camshaft position
before the engine starts, thereby adjusting camshaft timing
immediately upon start-up.
NOTE-
. VANOS system troubleshooting and diagnostics is best
accomplished using a scan tool.
. Diagnostic Trouble Codes (DTCs) pertaining to the
VANOS system are listed
in the following table. See also
OED On-Board Diagnostics.
Elevated oil temperatures can cause VANOS to deactivate.
Oil that is too thick (high viscosity) may cause
a DTC to be
set
in the ECM. If VANOS is deactivated (limp-home
mode), there will be a noticeable loss of power.
VANOS fault codes
BMW code P-code Fault description
19
PI529 VANOS solenoid valve activation,
exhaust
21
PI525 VANOS solenoid valve activation,
intake
103
PI519 VANOS faulty reference value
intake
104
PI520 VANOS faulty reference value
exhaust
105
PI522 VANOS stuck (Bank I) intake
106
PI523 VANOS stuck (Bank 2) exhaust

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1 17-36
Camshaft Timing Chain
1 Double VANOS control unit
1. BoltM6
2. Exhaust camshaft position
sensor
3. Sealing ring
4. Camshaft end sealing plug
-tighten to 50 Nm (37 ft-lb)
5. Camshaft seal cap
6. VANOS hydraulic piston set
screw -CAUTION: left hand
thread -tighten to
10 Nm
(89 in-lb)
7. Nut M7 -tighten to
14 Nm
(1 0 ft-lb)
8. Engine lifting hook
9. Stud M7
10. Nut
M6 -tighten to 10 Nm
(89 lb-in)
11. Gasket
12. Cylinder head
13. Sealing ring
14. Intake camshaft sensol
15. Bolt M6
16. VANOS control unit
17. Copper sealing ring
18. VANOS oil feed line
19. Banjo bolt -tighten to 32 Nm
(24ft-lb)

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11 7-39
Camshaft Timing Chain
4 Cover oil hole in VANOS control unit (arrow) with shop towel
to capture oil which will spray when compressed air line is
connected.
- Connect compressed air line to air fitting. Apply air pressure
set to
2 - 8 bar (30 - 110 psi).
4 With compressed air line connected, turn engine clocltwise
using crankshaft center bolt at least two rotations, until cylin-
der
1 is at (TDC) position (intake and exhaust carnshafl lobes
as shown arrows).
Do not rotate engine
countercloclwise to reach the top dead
centerposition. Instead, complete another two complete
Remove sealing plug from bore under starter. Lock
crank-
shafl in TDC position with BMW special tool 11 2 300
(arrow).
-
4 Unscrew and remove threaded studs (arrows) at rear of
cylinder head.

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. .. ~-
Camshaft Timing Chain -
4 Secure camshafts in TDC position using BMW special tool
set
11 3 240.
- Disconnect compressed air line, leaving compressed air fit-
ting attached to VANOS control unit.
NOTE -
Oil will drain from pressure line. Have a container and rags
ready
4 Unscrew sealing plugs from VANOS control unit (arrows).
NOTE-
Oil will drain from sealing plug bores. Have a container and
rags ready
4 Pull sealing caps straight out of VANOS control unit with
BMW special tool 11 6 170, or with short nose pliers.
NOTE-
Additional oil may drain from VANOS control unit.
4 Remove set screws (left-hand thread) on ends of intake and
exhaust camshafts.
NOTE-
Set screws have left hand threads. Remove with a clockwise
motion.