1999 BMW 540i Timing chain

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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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Camshaft Timing Chain
VANOS control unit, removing
(M52 TU and M54 engines)
This procedure includes removal of the Double VANOS con-
trol unit.
NOTE-
If the Double VANOS control unit is being replaced, camshaft
timing must be checked. This procedure requires multiple
special tools. Be sure to read the procedures through before
beginning the repair.
- Working inside luggage compartment, disconnect negative
(-) battery cable.
Prior to disconnecting the
batteg read the battery discon-
nection cautions given in
001 General Cautions and
Remove engine cooling fan assembly. See 170 Radiator
and Cooling System.
Remove engine trim covers.
Pry out plastic trim caps (arrows).
Remove cover fasteners, oil filler cap, and covers.
Remove ignition coils:
Disconnect ignition coil electrical harness connectors.
Remove coil mounting fasteners and coils.
NOTE-
Make note of ignition coil ground strap locations.
Remove spark plugs,

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11 7-38
[Camshaft Timing Chain
4 Disconnect electrical harness connector (A), oil line fitting
(B), and cranltcase vent tube (squeeze at arrows).
NOJE-
Oil will drain from VANOS unit fitting. Use shop rags to keep
oil off drive belts.
- Remove cylinder head cover fasteners, and cover.
4 Remove oil baffle cover from intake camshaft
4 D~sconnect electrical connections from exhaust camshaft po-
sition sensor and VANOS control valve (arrows).
4 Using banjo bolt from VANOS control unit oil line, install test
fitting
(BMW special tool 11 3 450) to VANOS control unit.

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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.

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Camshaft Timing Chain
4 Remove VANOS unit:
Remove fasteners from engine support eye.
Remove VANOS mounting nuts (arrows) from cylinder
head. Slide VANOS control unit and metal gasltet off.
NOJE-
The VANOS control unit will contain residual oil. Place
shop towels beneath adjustment unit when removing.
If the VANOS control unit is replaced, or if repair operations
are completed that may change camshaft timing, the cam-
shaft timing must be checked as described in VANOS tim-
ing,
checlcing and adjusting (M52 JU and M54
engines).
CAUJION-
Do not crank the engine with VANOS unit removed.
Piston/valve interference may result.
VANOS control unit, installing
(M52 TU and M54 engines)
< Clean contact edges of cylinder head face and double
VANOS control unit and apply a thin coat of sealing com-
pound (Three Bond
1209 8 or equivalent) to surfaces.
I CAUJION-
. Make sure all gaskel material is removed from lace of
cyl~nder head. Clean sealing lace and keep lree of oil.
Checklocating dowel (A) and dowelsleeve (B) at top of
cylinder head for damage or incorrect installation.
NO
JE -
If the Double VANOS control unit is beino reolaced. be -.
sure to check and adjust camshaft timing, see VA NOS
timing, checking and adjusting (M52 JU and M54 en-
gines).
* If work being carried out has no effect on camshaft timing,
it is not necessary to recheck the timing. It is recommend-
ed, however, that the VANOS operation be checked using
a compatible scan tool once the engine is running.