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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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11 6-9
Cvlinder Head and valvetrain1
4 Remove ignition coils and spark plugs.
V-8 models: remove mounting nuts (arrows) from wiring har-
ness ducting.
< V-8 models: disconnect fuel injector electrical connectors
from injectors:
Pry one corner of wire
loclc clip (arrow) on first injector.
Repeat for all injectors.
Lift wire ducts off and set aside.
- V-8 models: disconnect battery jump start post terminal from
left cylinder head cover.
- 6-cylinder models: remove oil filler cap and unclip vent con-
nection from cylinder head cover.
- Remove cylinder head cover mounting fasteners and re-
move cylinder head cover(~).
NOTE-
The cylinder head cover mounting bolt insulators and gas-
Icets should be reinstalled in their original locations. Make
note of their arrangement
during removal.
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116-12
I Cylinder Head and Valvetrain
Camshaft and lifter removal and installation
(M52 engine)
Camshafts and lifters, removing (M52 engine)
WARNING
-
The process of evenly loosening the camshaft bearing cap
nuts is NOT an acceptable method of removing the cam-
shafts. Special tools should always be used to remove the
camshafts. Be sure to read the procedure
tlirough before
starting a job.
I Allow engine to cool before beginning this procedure. /
- Disconnect negative (-) cable from battery.
CAUTION-
Prior to disconnecting the batfew read the battery discon-
nection cautions given in
001 General Cautions and
Warnings.
- Remove VANOS control unit from cylinder head. See 117
Camshaft Timing Chain.
I I 4 Remove loosened bolts (arrows) from front of exhaust
sprocket
nuts
(arrows) from intake camshaft
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1 Cvlinder Head and valvetrain1
Evenly tighten down bearing cap nuts in 'I? turn steps start-
ing at number
1.
Tightening torque
Camshaft bearing cap 14 Nm (10 ft-lb)
BMW special tool 11 3 430 on camshaft.
4 Rotate camshafts until marker bores (arrows) point up-
wards.
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- -
Cylinder Head and valvetrain1
4 Bearing caps are marked with a code for location.
NOTE-
The camshaft caps are stamped with a code letter - "E for
the intake side and
'HA" for the exhaust side. Number code is
for position on head, with number
1 being the front bearing
cap.
CA UTIOI\C
Do not mix up camshaft bearing caps.
Install and evenly tighten down bearing cap nuts in
'I2 turn
steps starting at number
1.
Tightening torque
Camshaft bearing cap 14 Nrn (10 ft-lb)
4 Install BMW special tool 11 3 430 on camshaft.
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Table d. Valve guide specifications
Specifications
All engines (1997-2002)
Valve guide wear, maximum 0.5 mrn (0.020 in)
(valve tilt clearance
measured
with new valve)
Valve guide inside diameter,
installed
(tolerance per IS0 allowance H7)
Standard 6.0 mm (0.236 in)
Oversize
1 6.1 mrn (0.240 in)
Oversize 2 6.2
mm (0.244 in)
Valve stem oil seals
The purpose of the valve stem oil seal is to prevent excess oil
from entering the combustion chamber. The sign of faulty
valve stem oil seals is excessive oil consumption and smoke
from the exhaust immediately after starting and during decel-
eration.
NOTE-
Valve stem oil seals should not be reused. If valves are re-
moved, new valve stem oil seals should be installed.
Valve stem oil seal replacement requires that the cylinder
head be disassembled and the valves removed as described
above under Valves, removing and installing.
NOTE-
BMW special tools are available to remove the valve stem oil
seals. As an alternative, standard valve seal removal tools
are available from most automotive parts stores.
Lubricate new seal and install using hand pressure only. Be
sure to install valve spring
seat(s) before installing seal.
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1 17-2
Camshaft Timing Chain
This repair group covers timing chain and VANOS repair
information for the following engines:
M52 (Single VANOS 6-cylinder engine)
M52
TU and M54 (Double VANOS engines)
M62 (Non VANOS
V-8 engine)
NOTE-
The M62 TU V-8 engine with VANOS Variable Camshaft
Timing repair information is not included.
NOTE-
See 100 Engine General for engine code and application
information.
Worn timing chains and sprocltets can lead to noisy operation
and erratic valve timing. Afaulty tensionercan also cause tim-
ing chain noises.
For specific repair procedures, refer to the appropriate repair
group:
020 Maintenance
113 Cylinder Head Removal and Installation
119 Lubrication System
121 Ignition System
170 Radiator and Cooling System
Special tools
Special BMW service tools are needed to perform the service
and repairs procedures covered in this repair group. Many of
these tools are expensive and only available through an au-
thorized BMW dealer. Be sure to read each procedure thor-
oughly before starting a job to determine which special tools
will be necessary.
In addition, Double VANOS system diagnosis can only be
carried out by using BMW specific electronic scan tools, such
as BMW
DISplus, MoDiC or equivalent.
4 Torque wrench wl flex extension
(Tool No. BMW 00
9 250)
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I Camshaft Timing Chain
Mark 0" location on socket (arrow). Tighten hub bolt in four
stages.
Tightening torque Vibration damper
hub to cranlrshaft
Stage 1 100 Nm (74 it-lb)
Stage
2 60" Torque angle
Stage
3 60" Torque angle
Stage
4 30" Torque angle
- install vibration damper and mounting bolts
NOTE-
Male sure to align vibration damper with locating dowel pin
in hub.
Tightening torque Vibration damper to
cranltshait hub (ME) 22 Nm (16 ft-lb)
- Install drive belts. See 020 Maintenance.
- Install cooling fan. See 170 Radiator and Cooling System.
- Replace under engine splash shield, then reconnect nega-
tive battery cable.
!/ANBS CONTROL UNIT AND
TIMING CHAIN (M52 ENGINE)
VANOS control unit, removing (M52 engine)
NOTE-
Special BMW service tools are required to remove and in-
stall the
VANOS control unit. Read the procedure through
before starting the job.
If the camshafts are notproperly timed, the pistons can
contact the valves.
- Disconnect negative (-) cable from battery.
CAUTION-
Disconnecting the battery may erase fault code(s) stored in
control module memory. Prior to disconnecting the
battev,
check for fault codes using special BMW diagnostic equip-
ment.
* Prior to disconnecting the battery, read the battery dis-
connection cautions given in
001 General Cautions
and Warnings.