1999 BMW 525i Workshop Manual

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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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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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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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11 6-60
Cylinder Head and Valvetrain
Valve springs
The valve springs should be checked for fatigue. To quickly
check the springs, line them up in a row. Place astraight edge
across the top of the springs. Any spring that is significantly
shorter than the others is worn and should be replaced.
Valve spring specifications and wear limits are not available
from
BMW.

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11 7 Camshaft Timing Chain
General ........................... .I I 7-2 Double VANOS System
Special tools ........................ .I 17-2 (M52 TU and M54 engines) ......... 11 7-34
Crankshaft Oil Seal, Front ........... I 17-6
Crankshaft oil seal, front,
replacing
(M52 engine) ................ .I1 7-6
Crankshaft oil seal, replacing
(M52 TU and M54 engines) ............ .I 17-9
Crankshaft oil seal, replacing
(M62 and M62 TU engines) ........... .I1 7-1 1
VANOS Control Unit and
Timing Chain
(M52 engine) ........ ,117-14
VANOS control unit, removing
(M52 engine) ...................... ,117-1 4
VANOS control unit, installing
(M52engine) ....................... 117-19
VANOS timing, checking and adjusting
(M52 engine) ...................... .I1 7-22
Timing chains, removing (M52 engine) . . ,117-26
Timing chain, installing (M52 engine) .... ,117-30
bouble VANOS system Tunctidn ........ 11 7-34
Double VANOS control unit ............ 117-36
VANOS control unit, removing
(M52 TU and M54 engines) ............ 11 7-37
VANOS control unit, installing
(M52 TU and M54 engines) ............ 1 17-41
VANOS timing, checking and adjusting
(M52 TU and M54 engines) ............ 1 17-43
Timing chains assembly
(M52 TU and M54 engines) ............ 1 17-50
Timing chains, removing
(M52 TU and M54 engines) ............ 11 7-51
Timing chains, installing
(M52 TU and M54 engines) ............ 11 7-57
Timing Chain (M62 engine to 9/98) . . 117-66
Timing chains, removing
(M62 engine to 9/98) ................. 11 7-66
Timing chains, installing
(M62 engine to 9/98) ................. 1 17-74
Camshaft timing, checking and adjusting
(M62engine) ....................... 117-79

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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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1 17-3
Camshaft Timing Chain
4 Crankshaft seal installation bushing, V-8
(Tool No. BMW 11 1 220)
4 Upper timing cover Installation tool, V-8
(Tool No. BMW 11
1 41 11412)
4 Crankshaft hub locking tools (6-cylinder engine with 2 piece
vibration dampener) (Tool No. BMW
11 2 150 11 1 2 410)
4 Cranltshaft loclting tool
(Tool No. BMW
11 2 300)
I I 4 Seal extractor tool set
(Tool No. BMW 11 2 380)

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[Camshaft Timing Chain
4 Camshaft locking tool set, 6-cylinder
(Tool No. BMW
11 3 240)
- 4 Crankshaft seal installation bushing. 6-cylinde~
4 Secondary chain tensioner locking pin set. 6-cylinder
(Tool No.
BMW 11 3 290)
11 3292
4 Secondary chain tensioner loclting pin, V-8
(Tool No. BMW 11 3 310)
4 Air line fitting
(Tool No. BMW
11 3 450)
4 Protractor
(Tool No. BMW
11 3 460)