1999 BMW 525i Workshop Manual

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11 6 Cylinder Head and Valvetrain
........................... General ............................ 1 16-2 Valves 116-56
.................... Special Tools ........................ 11 6-2 Valves. leak test 11 6-56
......... Valves. removing and installing 11 6-56 Cylinder Head ..................... .I1 6.5 ....................... Valve guides 11 6-57
Valves. leak test ...................... 11 6-6
Valve stem oil seals .................. 11 6-58 ...... ..""""."""ll 6.6 Valveseats ........................ 116-59 Hydraulic lifters, checking and replacing .. .I1 6-7 Valve ....................... 6-60 . .
Camshaft andLifter Removal
and Installation
.................... 11 6-1 1
Camshaft and lifter removal and
installation
(M52 engine) ............. .I1 6.12
Camshaft and lifter. removal and
installation (M52
TU and M54 engine) .... 11 6-1 9
Double VANOS timing chain components
. 11 6-28
Camshaft removal and installation
(M62 engine)
....................... 11 6-39

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This group covers cylinder head and valvetrain service and
repair. Some of the repair procedures described here require
that the cylinder head first be removed as described in
113
Cylinder Head Removal and Installation.
NOTE- For timing chain and
VANOS repair information, see 117
Camshaft Timing Chain.
If it is
determined that the cylinder head will require signif-
icant reconditioning work, a remanufactured cylinder head
may be a good alternative. Remanufactured cylinder
heads are available from an authorized
BMW dealer.
The information given in this repair group is organized ac-
cording to engine code. For engine application information,
see
I00 Engine-General.
For specific repair procedures, refer to the appropriate repair
group:
* 020 Maintenance
100 Engine-General
113 Cylinder Head Removal and Installation
117 Camshafi Timing Chain
= 170 Radiator and Coo!ing System
Special Tools
Special BMW tools are required for most cylinder head ser-
vice described in this repair group. Many of these tools are ex-
pensive and only available through an authorized
BMW
dealer. If the special tools are not available, have the cylinder
head removed and disassembled by an authorized BMW
dealer. Be sure to read each procedure thoroughly before
starting a job to determine which special tools and equipment
will be necessary.
Most of the repairs to a cylinder head require precision
rna-
chine work to specific tolerances. This type of work should be
performed by an authorized BMW repairfacility or an ASE
certified machinist.
71 Torque wrench with flex shaft

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1 16-3
Cylinder Head and Valvetrain
4 Cranltshaft loclting tool (Tool No. BMW 11 2 300)
4 Camshaft loclting tools set (V-8, cyl. 1-4)
(Tool No.
BMW 11 2 440)
4 Camshaft locking tools set (V-8, cyl. 5-8)
(Tool No. BMW 11 2 440)
4 Camshaft loclting tools set (6-cylinder)
1 (Tool No. BMW 11 3 240)
4 Camshaft bearing cap tensioning jig (6-cylinder)
ITool NO. BMW 11 3 260/27n

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/cylinder Head and Valvetrain
Secondary timing chain tensioner locking pin set (6-cylinder)
- 4 Secondary timing chain tensioner locking pin (V-8)
(Tool No. BMW
11 3 310)
4 Adjustable primary timing chain tensioner tool (V-8)
(Tool No. BMW
11 3 390)
4 Camshaft installation tool (V-8)
(Tool No.
BMW 11 3 430)
4 VANOS compressed air fitting
7 (Tool No. BMW 11 3 450)
Adjustable primary timing chain tensioner tool (6-cylinder) (Tool No. BMW
11 4 220)

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11 6-5
I Cylinder Head and valvetrain1
4 Timing chain tensioner bracket (V-8)
(Tool No. BMW
11 7 380)
CYLINDER HEAD
This section provides the specifications and special recondi-
tioning information necessary to repair the cylinder heads
covered by this manual.
The disassembled cylinder head should be inspected for
warpage and cracks. Check the valve guides and valve seats
for wear before machining a warped head. Always decarbon-
ize and clean the head before inspecting it.
Visually inspect the cylinder head for craclts.
If a cracked cyl-
inder head is suspected and no
craclts are detected through
the visual Inspection, have the head further tested for cracks
by an authorized BMW dealer or an ASE certified machinist.
A cracked cylinder head must be replaced.
NOJE-
When disassembling and inspecting the cylinder head, be
sure to
checlc the camshaft carrier bearing surfaces using a
straight edge for
warpage, and check the lifter bores for wear.
A high-quality straight edge can be used to
checlc for
warpage. A warpage of 0.05 mm (0.002 in.) is acceptable
without machining. A warped cylinder head can be machined
provided no more than 0.3
mm (0.012 in.) of material is re-
moved.
If further machining is required, the head should be
replaced. Removing more than this amount will reduce the
size of the combustion chamber and adversely affect engine
performance. A 0.3 mm
thicker head gasket for machined
heads is available from an authorized BMW parts depart-
ment.

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11 6-6
Cylinder Head and Valvetrain
4 Before machining the head to correct for warpage, measure
the total height
(A) (thickness of the cylinder head). Minimum
height specifications are given in Table a. Cylinder head
height.
NOTE-
6 cylinder and V-8 engines share cylinder head height spec-
ifications.
Table a. Cylinder head height
New Minimum height
(A)
140.0 rnrn (5.512 in.) 139.7 rnrn (5.500 in.)
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.
Camshaft wear
Camshaft wear is usually caused by insufficient lubrication.
Visually inspect camshaft lobes and journals for wear. Cam-
. ~~ shaft wear specifications are given in Table b. Camshaft
wear specifications.
CA UTIOI\C
If the camshaft is being replaced due to cam lobe wear, it is
recommended that the corresponding lifters should also be
replaced to avoid damaging the new camshaft
Table b. Camshaft wear specifications
6 cylinder engines V-8 engines
Axlal play 0.150-0.330 rnrn 0 200-0 360 rnrn - .-
(0.0060-0 013 in.) (0.008 - 0.014 in ) - - Radlal play 0.020-0.054 rnrn 0.040-0.074 rnrn
(0.0008-0.0021 in.) (0.016 - 0.029 in.)

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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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Cylinder Head and Valvetrain
&cylinder models: remove plastic top
- Pry out caps (arrows).
- Remove fasteners and covers. covers:
4 V-8 models: remove plastic top
covers:
Press down on locking pins
(arrows) to release locks and
remove top cover.
Pry out caps
(A) from covers.
Remove fasteners and covers.
4 Lift metal latch on coil harness connectors and disconnect
harness connectors from coils. 6-cylinder shown,
V-8 similar.
- Remove coil grounding straps.
NOTE-
Make note of ground wire at mounting studs arrangement
during removal.
- -- -
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