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1 17-24
I Camshaft Timing Chain
4 Remove banjo bolt from VANOS unit oil feed line and install
BMW special tool 11 3 450.
NOTE-
Oil will drain from oil feed line.
- Connect compressed air line (with pressure set to 2-8 bar or
30-1 10 psi.) to air fitting.
4 Measure gap (A) between secondary timing chain tensioner
and
intake camshaft sensor wheel. Make note of distance.
4 Connect cable test (BMW special tool 11 6 410) to VANOS
connector. Connect positive clip to positive battery terminal.
- Connect negative clip to battery negative terminal.
CAUTION-
Reversing terminals on special tool will damage diode on
VANOS solenoid valve.
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-
Camshaft Timing Chain -. -
Measure gap (B) between secondary timing chain tensioner
and intake camshaft sensor wheel. Make note of distance.
To determine VANOS control travel:
Distance
I3 - distance A = a minimum of 8.5 mm
CAUTION-
If the adjustment travel is less than 8.5 mm the VANOS ad-
justment unit must be removed and readjusted. See
VANOS
control unit, removing (M52 engine)
and VANOS con-
trol unit, installing
(M52 engine).
Remove special tools:
Cranltshaft locking tool.
Camshaft
loclting tool set.
Air fitting.
* VANOS cable adaptor.
- Install VANOS oil line with new seal
- Install oil baffle cover above intake camshaft.
- Install cylinder head cover mounting studs to rear of head.
- Install cylinder head cover,
Tightening
torques
Cylinder head cover 10 Nrn (89 in-lb)
VANOS oil line
32 Nm (24 R-lb)
VANOS solenoid to control unit 30 Nrn (22 ft-lb)
- Installation of remaining parts is reverse of removal.
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Camshaft Timing Chain Timing chains, removing
(M52 engine)
Camshaft timing chain removal on M52 engines requires en-
gine oil pan removal.
Special
BMW sewice tools are needed for timing chain re-
moval and installation procedures. The special tools assure
propertiming of thevalvetrain. Precise marks to
setthe timing
on the camshafts are not provided for reassembly. Read the
procedures through before beginning the job.
NOTE-
If the camshafts are not properly timed, the pistons can con-
tact the valves.
- Remove VANOS control unit. See VANOS control unit, re-
moving (M52 engine).
- Remove radiator cooling fan and shroud. See 170 Radiator
and Cooling System.
- Drain cooling system. See 170 Radiator and Cooling Sys-
tem.
- Remove coolant hoses from thermostat housing and remove
thermostat housing from front of cylinder head.
- Loosen bolts for coolant pump pulley.
- Remove drive belts for alternator and AIC compressor. See
020 Maintenance.
- Remove coolant pump pulley.
Remove drive belt tensioner mounting bolts (arrows) and re-
move tensioner from front of engine.
- Remove engine speed sensor from lower timing chain cover.
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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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-- -
Chain 1
- Install cylinder identification trigger plate to front of intake
camshaft.
- 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 spring plate to intake cam
sprocket.
Tighten intake camshaft sprocket nuts.
- Install VANOS control unit, see VANOS control unit, install-
ing
(M52 engine).
Tightening torque
Intake camshaft sprocket nuts to studs
(ME) 1011 Nm (8919 In-lb) 502117068
- Unlock and release secondary chain tensioner,
4 Preload primary timing chain by torquing adjustable primary
chain tensioner (BMW special tool
11 4 220) to 1.3 Nm
(11 in-lb).
- Tighten exhaust camshaft sprocket bolts in two stage
Tightening torque Exhaust camshaft sprocket bolls (M7)
Stage 1
5 Nrn (44 in-lb)
Stage
2 22 Nm (17 ft-lb)
- Remove crankshaft locking tool and camshaft locking tools.
< Align hub with keyway and tap into place. Insert new center
bolt with washer shoulder (arrow) facing hub.
CAUTION-
Inspect woodruff ley for damage before installing hub.
- Attach crankshaft holding tool (BMW special tools 11 2
15011 1 2 410) to hub. Counterhold hub with tool while tight-
ening center bolt.
CAUTION-
Do not use flywheel locling tool to hold crankshaft stationary
to loosen or tighten
cranlshaft hub center bolt. Use only the
special tools specified, or equivalent hub holding tool.
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-- Camshaft Timing Chain -- -
Tightening torque
Vibration damper hub to crankshaft
410 Nm (300 ft-lb)
4 Install cranltshaft hub and vibration damper while aligning
locating hole (arrow) in damper with dowel pin in hub.
Tightening torque
Vibration damper and
pulley to
cranltshaft hub
22 Nm (17 ft-lb)
- Turn engine over by hand in direction of rotation at least two
full rotations. Reinstall camshaft and crankshaft locking
toois
to recheck engine timing. Remove locking tools if no faults
are found.
- Remove BMW special tool 11 3 390 (dummy tensioner) from
side of cyiinder head.
- Install primary chain tensionerso that cutout in tensioner pis-
ton engages chain rail.
Tightening torque
Timing chain tensioner to tensioner sleeve
70 Nm (52 ft-ib)
- Install cylinder head cover mounting studs, camshaft cover,
and cylinder head cover.
Tightening torque Cylinder head cover to cyiinder head
M6 nut 10 Nm (89 in-lb)
MB bolt 22 Nm (17 ft-lb)
- installation of remaining parts is reverse of removal, noting
the following:
When installing thermostat, make sure arrow or vent hole
faces up, if applicable.
Refill cooling system as described in
170 Radiator and
Cooling System.
Fill engine with oil and install new
oil filter as described in
020 Maintenance.
Tightening torque Upper timing chain cover to cylinder head
M6 nut 10 Nm (89 in-lb)
MB bolt 22 Nm (17 ft-lb)
VANOS oil supply pipe to VANOS control
unit banjo bolt
32 Nm (24 ft-ib)
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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