1997 BMW 525i cool

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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
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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Camshaft Timing Chain
- Connect electrical harness connectors to camshaft position
sensors and VANOS solenoid valves.
- Remove BMW special locking tools from rear of cylinder
head.
- Remove cranltshaft locking tool and replace sealing plug.
Install intake camshaft baffle and cylinder head cover.
Checlc 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
(B) of half-moon cutouts.
Similarly, seat gasket and
seal corners in front of cylinder
head, at VANOS control unit.
Tightening torque
Cylinder head cover to cylinder head
(M6) 10 Nm (89 in-lb)
- Remainder of installation is reverse of removal.
Tightening torques
Radiator fan (viscous clutch) to
coolant pump 40
Nm (30 ft-lb)
Spark plug to cylinder head
25 Nrn (18 ft-lb)
VANOS timing, checking and adjusting
(M52 TU and M54 engines)
Use this procedure to check and, if necessary, adjust cam-
shaft timing. This procedure assumes that the cylinder head
cover and intake
camshaft plastic baffle have been removed.
Also, be sure the cooling fan and the spark plugs have been
removed.
Remove primary camshaft chain tensioner cylinder
(arrow).
~~ ~ ~~ ~--~
CA UTlOAC
Primary camshaft chain tensioning piston is under spring
pressure.

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-- - -- - -- Camshaft Timing chain1
- Remove camshaft locking tools from rear of camshafts
- Remove BMW special tool 11 4 220 (adjustable primary
chain tensioner). Reinstall primary chain tensioner.
Tightening torque Primary chain tensioner to cylinder head
70
Nm (52 it-lb)
- Remove crankshaft locking tool from transmission bellhous-
ing. Reinstall sealing plug.
- Remove VANOS setup bracket from front of cylinder head
- lnstall VANOS control unit as described earlier in this group.
- Remove compressed air fitting (BMW special tool 11 3 450)
from VANOS control unit.
- Fit VANOS oil line banjo bolt with new seals. Attach oil line to
VANOS control unit.
Tightening torque
Oil line to VANOS control unit (banjo bolt) 32 Nm (24 H-lb)
- Remainder of installation is reverse of removal, noting the fol-
lowing:
lnstall spark plugs.
* lnstall intake camshaft plastic baffle prior to installing cylin-
der head cover. lnstall ignition coil packs and connect elec-
trical harness connectors.
Install radiator cooling fan.
- lnstall air filter housing and top engine cover.
Tightening torque Radiator cooling fan
(VISCOUS clutch) to 40 Nm (30 ft-lb)
coolant pump
Cyitnder head cover to cylinder head 10 Nm (89 in-lb)
Sparlc plug to cylinder head 25 Nm (18 ft-lb)

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... -.
Camshaft Timing chain1
Timing chains, removing
(M52 TU and M54 engines)
Camshaft timing chain removal requires that the oil pan be re-
moved. See
119 Lubrication System. Also required is re-
moval of the VANOS control
unit and disassembly of the
intake and exhaust camshaft sprocket assemblies as de-
scribed earlier in this repair group.
Special BMW
service tools are needed for timing chain re-
moval and installation. The special tools assure proper timing
of the valvetrain. Precise
marlts to set the timing on the cam:
shafts are not provided for reassembly. Read the procedures
through before beginning the job.
CA
UTION-
If the camshafts are not properly timed, the pistons can con-
tact the valves.
- D~sconnect negative (-) cable from battery.
CAUTION-
* Disconnecting the battery may erase fault code@) stored in
control module memory. Check for fault codes using spe-
cial
BMW diagnostic equipment.
Prior to disconnecting the battery, read the battery dis-
connection
cautfons given in 001 General Cautions
and
Warninqs.
- Remove VANOS control unit. See VANOS control unit, re-
moving
(M52 TU and M54 engines).
Remove sealing plug from crankcase below starter and se-
cure crankshaft with
BMW special tool ll 2 300.
Drain engine cooling system. See 170 Radiator and Cool-
ing System.
Remove belt driven cooling fan, fan shroud, and thermostat
housing. See
170 Radiator and Cooling System.
Remove drive belts. See
020 Maintenance.
NOTE-
Mark direction of belt rotation if reusing belt.
- Remove water pump pulley fasteners and pulley.
- Drain engine oil and remove oil pan as described in 119
Lubrication System.

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~ ~~ ~
I Camshaft Timing Chain I --
lnstall crankshaft holding tool (BMW special tool 11 8 190/11
8 200). Make sure cut outs in tool engages openings in
damper assembly. While counterholding crankshaft with
special tool, remove crankshaft center bolt (A).
CAUTION-
Do not use flywheel locking tool to hold crankshaft stationary
NOTE-
The crankshaft hub centerbolt is tightened to a torque of 410
Nm (300 ft-lb).
4 Install crankshaft damper puller (BMW special tool 11 8 210)
to 11 8 200. and (A) remove damper from crankshaft.
The crankshaft must not be allowed to rotate when the timing
chains are loosened or removed. The pistons can contact the
valves. Use appropriate crankshaft holding tool when loosen-
ing crankshaft hub center bolt.
Using a drift of less than
5 mm diameter, drive two locating
dowels in left and right sides of lower timing
cham cover to-
ward engine. Remove cover mounting bolts
(arrows) and
carefully lift cover off.
CA
UTION-
* Use care when removing the cover from the cylinder heao
gasket. If the cover is stuck, use a sharp
knife to separate
it from the headgasket.
If cylinder liead gasket Is damaged, remove cylinder
head and replace head gasket. See
113 Cylinder
head and valvetrain.
NOTE-
- The chain cover can be removed with the coolant pump in-
stalled.
Use care when removing the cover from the coolant pipe
at rear.
- Push primary chain tensioner guide rail aside and remove
chain.

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(camshaft Timing Chain
- To install lower timing case cover:
- Clean cover and cylinder block sealing surfaces
Use new
gaskets and coolant pipe O-ring.
Remove timing chain cover dowel pins from engine block.
Drive timing cover dowels in until they just protrude slightly
from sealing surface.
Apply a small bead of silicon sealer (Three Bond 1209
63
or equivalent) to corners of cylinder head where timing
cover meets cylinder head and engine block.
Tap cover into position until firmly seated.
lnstall all bolts hand tight, including two Torx bolts from
above.
Install secondary chain lower guide.
Tighten cover mounting bolts alternately and in stages.
Tightening torque
Lower timing cover to cylinder
bloclc (M6) 10 Nrn (89 in-lb)
- Install oil pan with new gasket. See 119 Lubrication Sys-
tem.
Tightening torque
Oil pan
to engine bloclc (M6)
8.8 grade
10.9 grade 10 Nrn (89 in-lb)
12 Nm
(9 ft-lb)
- Align damper assembly with lteyway and tap into place. In-
sert new center bolt with washer.
CAUTION-
Inspect woodruff key for damage before installing hub
assembly.
- Attach special tools 11 8 20011 1 8 190 to damper assembly.
Counterhold damper with
11 8 190 while tightening center
bolt.
CAUTION-
Do not use BMW special tool 1 I 2 300 to hold crankshaft
stationary to tighten cranl(shaft hub center bolt. Use only
the special tools specified, or equivalent hub holding tool.
Have a second person hold special tool
11 8 190 while
tightening center crankshaft bolt.
Tightening torque Crankshaft hub to crankshaft 410 Nrn
(300
ft-lb)

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11 7-66
I Camshaft Timing Chain
4 install 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 8 or equivalent
sealant at corners
(B) of half-moon cutouts. Seal corners
in front of cylinder head at VANOS control unit.
Tightening torque
Cylinder head cover to cylinder head
10 Nm (89 in-lb)
- Remainder of reassembly is reverse of removal, noting the
following:
Secure all coolant hoses, thermostat housing, engine cool-
ant drains.
Install new engine oil filter and oil. See
119 Lubrication
System.
Refill and bleed cooling system as described in
170 Radi-
ator and Cooling system.
Use scan tool to check VANOS operation with engine
idling.
Tightening torques Coolant drain plug to cylinder block
25 Nm (18 ft-lb)
Radiator cooling fan (viscous clutch)
to coolant pump
40 Nm (30 ft-lb)
Radiator drain screw to radrator 2.5 Nm (22 in-lb)
Vibration damper hub to crankshaft 41 0 Nm
(300 ft-ib)
TIMING CHAIN
(M62 ENGINE TO 911998)
Timing chains, removing
(M62 engine to 911 998)
Camshaft timing chain removal requires that the engine oil
pan be removed.
Special
BMW service tools are needed for timing chain re-
moval and installation procedures. The special tools assure
propertiming of thevaivetrain. Precise marks to set the timing
on the camshafts are not provided for reassembly. Read the
procedures through before beginning the job.
CAUTION-
Special BMW service tools are needed for this procedure.
Read the procedure through before beginning the job. If the
camshafts are notproperly timed, the pistons can contact the
valves.