1998 BMW 528i ECT

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11 6-42
/ Cvlinder Head and Valvetrain
4 Using crankshaft center bolt, rotate engine clockwise one
complete rotation until the first cylinder is at TDC.
4 Confirm TDC position. Lobes of camshafts for cylinder head
1-4 (passengers side) should point up (arrows).
4 Remove timing chain tensioner (arrow) from right side upper
timing chain cover.
- Remove secondary air injection pipes in front of upper timing
chain covers.
- Remove left and right coolant hoses from coolant pump
housing.
- Detach dipsticlc tube from upper right timing cover,

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Cylinder Head and valvetrain1
While counter holding camshaft, remove exhaust camshaft
sprocket bolts
(arrows) from left cylinder head. Remove
sprocltets with chain.
< While counter holding camshaft, remove exhaust camshaft
sprocket bolts
(arrows) from right cylinder head. Remove
sprocltets with chain.
4 Use BMW special tool 11 3 430 to rotate camshaft into disas-
sembly position.
4 Loosen camshaft bearing caps nuts in correct sequence
(1-10) (left cylinder head shown).
NOTE -
Keep camshaft bearing caps in order. Used caps must not be
interchanged.
- Remove exhaust camshaft by repeating process.
0 Remove camshafts from cylinder head.
- Repeat camshaft removal process for right cylinder head.

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11 6-55
Cvlinder Head and valvetrain1
4 Remove cylinder head cover sealing gasltets from left cylin-
der head cover. Install BMW special tool 11 1 412 into gasket
groove of cylinder head cover.
Install left cylinder head cover. Fit cylinder head cover re-
taining nuts to cylinder head cover studs at cylinders
5 and
6 (first two cylinders on left side cylinder bank).
* Tighten nuts uniformly in 'I? turn steps.
NOTE-
BMW special tool 11 1 4 12presses upper timing chain cover
to level of cylinder head.
Tightening torque Cylinder head cover
nuts 10 Nm (7.5 it-lb)
- Tighten left upper timing chain cover retaining bolts in two
passes.
Tightening torque
Timing chain cover to head
10 Nm (7.5 ft-lb)
- Remove cylinder head covers and remove BMW special
tools 11 4 41 11412 from cylinder head covers.
- Fit new gasket to cylinder head cover without strain.
- Apply Three Bond@ 1209 sealant to joints between cylinder
head and timing cover.
4 Malte sure half-moon cutouts (A) at rear of cylinder heads fit
correctly to cylinder head sealing surface. Apply Three
Bond@ 1209 sealant at corners of half-moon cutouts (B).
- Remainder of installation is reverse of removal.

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1 16-56
Cylinder Head and Valvetrain
This section covers valve removal and reconditioning, includ-
ing valve guides, seats, springs, and valve stem oil seals.
Valves, leak test
To test the valves for leakage, the cylinder head must be dis-
assembled with camshafts and camshaft carriers removed.
With valve assemblies and spark plugs installed, place the
cylinder head on a workbench with the combustion chamber
facing upward. Fill each combustion chamber with a thin non-
flammable liquid. After fifteen minutes,
check the level of the
fluid. If the fluid level in any cylinder drops, that cylinder is not
sealing properly.
Valves, removing and installing
- Remove cylinder head as described in 113 Cylinder Head
Removal and Installation.
CAUTIOI\C
(M52 TU/M54 engines only) Do not let the hydraulic lifters
fall out as the camshaft carrier is removed. Special suction
cups are available from
BMW to hold the hydraulic lifters in
place during carrier removal.
* Hydraulic cam lifters should be stored m an uprfght po-
sition. If necessary, use a magnetic tool to
aidin remov-
al of the lifters.
- Remove valves using a valve spring compressor.
CAUTIOI\C
Label each valve assembly as it is removed so it can be in-
stalled in its original position.
-
- Remove and discard valve stem oil seals from valve guides.
See Valve stem oil seals later in this section.
- Valve installation is reverse of removal. Remove carbon de- - -
posits from the valves using a wire brush or wire wheel. -
-
Valve specifications are listed in Table c. Valve specifica-
tions.

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-
- - . - Cylinder Head and Valvetrain -
Table c. Valve specifications
Valve head diameter
lntaite 33.0 mm 33.0 mm 35.0 mm
Exhaust
30.5 mm 30.5 mm 30.5 mm
Valve stem diameter
- Standard
Intake
6.0 mm .0.025 6.0 mm -O.o" .o.040 6.0 mm .0.025 .0,040
Exhaust 6.0 mm -0.0"0 -0.055 6.0 mm -0.040 .0,055 6.0 mm .0.040 .0,055
Valve stem diameter - Oversize 1 (identified on stem as Rl)
Intake 6.1 mm -0.025 .0.040 6.1 mm .0-025 .0,040 6.1 mm -O.o" .o,040
Exhaust 6.1 mm .O.O4O ..,,,, 6.1 mm -0.040 -0.055 6.1 mm -0.040 .0,055
Valve stem diameter - Oversize 2 (identified on stem as R2)
Intake 6.2 mm -O-OZ5 6.2 mm -0.025 .0.040 6.2 mm -0.025 .0,040
Exhaust 6.2 mm -0.040 -0.055 6.2 mm -0.040 .o.055 6.2 mm -O."o .o,055
Valve guides
BMW does not supply valve guides as replacement parts. If a
valve guide is excessively worn, it should be reamed to ac-
cept oversized
valve stems. Valve guide specifications are
listed in
Tabled. Valve guide specifications.
- Valve guides should be checked for wear using a new valve.
Be sure to thoroughly inspect the cylinder head to ensure
that it can be reused before reworking the guides.
NOTE-
International Organization for Standardization (1.30) toler-
ance classes are listed in Table c.
IS0 allowances are
based on nominal sizes and should be used to determine
proper fit. Most machine shops should have this informa-
tion available.
Replacement valve guides may be available through after-
market suppliers. Valve guide replacement requires spe-
cial tools and a press. It is also necessary to heat the
cylinder head and chill the valve guides when replacing the
guides.
BMW supplies oversize valves. See Table d. Valve guide
specifications for additional information.

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Cylinder Head and valvetrain1
Valve seats
< The valve seats should be resurfaced whenever new valves
or valve guides are installed. Cutters are required to resur-
face the seats. Always check the valves for leaks after recon-
ditioning a valve seat as described above. Table e. Valve
seat specifications lists valve seat dimensions.
Table e. Valve seat specifications (refer to figure)
All
6 cylinder All 8 cylinder
engines (1997- engines (1997- Specification 2002) 2002)
Blllloc A -Valve seat angle 45" --. -- 45"
B - Correction angle, 15" 15"
outside
C - Correction angle, 60"
inside
D -Valve seat width
intalte
1.65 i0.25 rnrn 1.25 +0.25 rnm
(0.065 c0.010 in) (0.049 f 0.010 in)
exhaust
1.65 c0.25 rnm 1.65 i0.35 rnm
(0.065 fO.O1O in) (0.065 c0.014 in)
E - Valve seat outside diameter
intake
32.4 mm (1.276 in) 34.5 mm (1.358 in)
exhaust
M52: 29.4 rnm 30.0 rnm (1.181 in)
(1.157 in)
- M52 TU,
M54: 30.0 mrn
(1.181 in)
NOTE-
Standard size replacement valve seats are not available from
BMW Replacement valve seats are only available from BMW
in 0.4 mm oversize (oversized in both height and diameter).
The manufacturer does not provide specifications for valve
seat replacement for the engines covered by this manual.

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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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Camshaft Timing Chain
4 Crankshaft hub loclting tool. M54 engine
(Tool No.
BMW 11 8 190 11 1 8 200)
4 VANOS test lead, M52 6-cylinder
(Tool No.
BMW 12 6 410)
Crankshaft oil seal, front,
replacing
(M52 engine)
The crankshaft front seal is located in the lower timing cover,
behind the vibration damper.
- Disconnect negative (-) cable from battery.
CAUTIOIG
a Disconnecting the battery may erase fault code(s) 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 cautions given in
001 General Cautions
and
Warninqs.
- Remove splash guard from beneath engine.
- Remove engine cooling fan assembly. See 170 Radiator
and Cooling System.
NOTE-
Cooling ian nut (32 mm wrench) has left-hand threads.
- Remove drive belts. See 020 Maintenance.
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