1999 BMW 540i Oul

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Lubrication System
To test switch, connect an ohmmeter between terminal in
switch body (arrow) and ground. With engine off, there
should be continuity. With engine running, oil pressure
should open switch and there should be no continuity. Re-
place a faulty switch.
CAUTION-
Keep in mind that low oil pressure may be preventing the
switch from turning the light out
If the light remains on while
the engine is running, check the oil pressure as described
earlier. Do not drive the car until the problem is corrected. The
engine may be severely damaged.
Crankshaft rear main seal replacement requires removal of
the transmission and flywheel.
Crankshaft rear main seal, replacing
(&cylinder)
- Remove transmission. See 230 Manual Transmission or
240 Automatic Transmission.
- Manual transmission vehicles: Remove clutch pressure plate
and disc. See
210 Clutch.
- Remove flywheel. See 210 Clutch or 240 Automatic Trans-
mission.
- Drain engine oil.
4 Remove seal carrier bolts from oil pan (arrows). Loosen all
oil pan bolts.

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119-12
Lubrication System 1
4 Support subframe from below using BMW special tool 31 2
220 and appropriate shop lift. Remove
subframe mounting
bolts and lower
subframe as far as possible.
Remove oil pan screws (arrows) at cylinder block and trans-
mission bellhousing. Lower and remove oil pan.
NOTE-
If oil pan will not slide backwards, disconnect stabilizer bar
links and lower front axle support further.
If the oil pan does not separate easily from the engine cylin-
der
block, a few taps with a rubber malletshould breakit free.
Do not
pry the oil pan loose.
When installing oil pan: Thoroughly clean all old gasket material from mating sur-
faces and use a new gasket.
Apply a small amount of non-hardening sealer
(3 Bond
12098 or equivalent) to oil pan gasket directly below joints
(arrows) for end cover and front timing case cover. Apply
a bead
3 mm wide by 2 mm high.
Install all oil pan bolts finger tight. Tighten oil pan bolts to-
ward front of engine first, then pan bolts at transmission
end.
Tightening
torques
Oil drain plug to oil pan (M12) 25 Nm (18 ft-lb)
Oil pan to engine block
MG (8.8 grade)
MG (10.9 grade)
M8 (8.8 grade)
10 Nm (89 In-lb)
12 Nm (9 ft-lb)
22 Nrn (16 R-lb)

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.
[Lubrication System
< Disconnect electrical harness connector (arrow) at oil level
sensor.
< Remove lower oil pan mounting bolts (arrows)
CAUTIOI\C
If the lowerpan does not separate easily from upperpan, a
few taps with a rubber mallet should break it free. Do
notpry
the oil pan loose.
- When installing oil pan:
Thoroughly clean all old
gasltet material from mating sur-
faces and use a new gasket.
4 Install threaded guide studs at locations marked by arrows
to guide new oil pan
gasltet and oil pan into position and to
prevent damage to sealing lip.
- Install new oil pan mounting bolts (threads coated with
sealer).
Remove guide studs and install remainder of oil pan bolts.
- Remainder of reassembly is reverse of disassembly
- After adding engine oil, start and run engine. Raise engine
speed to 2,500 rpm until oil pressure warning light goes out
(about 5 seconds).
Tightening torques Lower oil pan to upper
oil pan
M6 (8.8 grade) 10 Nm (89 in-lb)
M6 (10.9 grade) 12 Nm (9 ft-lb)
M8 (8.8 grade) 22 Nm (16 ft-lb)
Oil drain plug to oil pan (M12) 25 Nm (18 ft-lb)

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1 19-1 7
Lubrication System
Disconnect electrical harness connect01
sensor.
. (arrow)
4 Remove lower oil pan bolts (arrows) and pan, oil
level
CAUTION-
If the lowerpan does not separate easily from upperpan, a
few taps with a rubber mallet should break it free. Do not pry
the oil pan loose.
Remove
NC drive belt tensioner.
Remove adjustment bolt
(B).
Remove retaining bolt (A) and remove tensioner from oil
pan.
- Remove power steering pump from engine block, leaving hy-
draulic lines connected. Suspend from chassis using stiff
wire. See
320 Steering and Wheel Alignment.

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120-3
Ignition System
Warnings and cautions
The ignition system produces dangerous high voltage. In ad-
dition the sensitive electronic components can be damaged
if
proper precautions are not adhered to.
WARNING-
* Do not touch or disconnect any cables from the coils while
the engine is running or being
cranked by the starter.
The ignition system produces high voltages that can be
fatal. Avoid contact with exposed terminals. Use ex-
treme caution when working on a car with the ignition
switched on or the engine running.
- Connect and disconnect tlie DME system wiring and
test equipment leads only when the ignition is
OFF:
Before operating the starter without starting the engine
(for example when
making a compression test) always
disable the ignition.
CA
U TIOW-
Do not attempt to disable the ignition by removing the coils
from the spark plugs.
Connect or disconnect ignition system wires, multiple
wire connectors, and ignition test equipment leads only
while the ignition is
off Switch multimeter functions or
measurement ranges only with the test probes discon-
nected.
* Do not disconnect the battery while the engine is run-
ning.
A high impedance digital multimeter should be used for
all voltage and resistance tests. An LED test light
should be used in place of an incandescent-type test
lamp.
In general, make test connections only as specified by
BMW as described in this manual, or as described by
the instrument manufacturer.
Engine management
BMW €39 engines use an advanced engine management
system known as Digital Motor Electronics (DME). DME in-
corporates on-board diagnostics, fuel injection, ignition and
other engine control functions. DME variants are listed in
Table a. Engine management systems.
Second generation On-Board Diagnostics
(OED II) is incor-
porated into the engine management systems used on the
cars covered by this manual. Use a BMW-specific electronic
scan tool, or a "Generic"
OED II scan tool to access Diagnos-
tic Trouble Codes (DTCs). DTCs can help pinpoint ignition
ine management problems.

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120-6
lgnition System
lgnition system, troubleshooting
Troubleshooting ignition system faults should begin with an
interrogation of the On-Board Diagnostics (OBD
II) system.
The OBD
II system detects ignition system misfire and other
related faults. When faults are detected, the OBD
II system
stores a Diagnostic Trouble Code (DTC) in the Engine Con-
trol Module (ECM) along with other pertinent fault information.
4 In addition, the Malfunction Indicator Light (MIL) will come on
if an emissions related fault is detected. Additional OBD
II in-
formation, including a DTC lookup table, can be found in
OED On-Board Diagnostics.
NOTE-
BMWmodels covered in this manual were equipped with one
of three versions of
MIL warning lights (as shown).
Misfire detection
Engine m~sfire in one or more cylinders, may be caused by a
var~ety of malfunctions in various subsystems. The OBD II
system ~ncorporated into the engine management systems is
des~gned to detect and warn of misfire faults during englne
operat~on. See OED On Board Diagnostics.
WARNING -
lgnition misfires can cause high hydrocarbon exhaust emis-
sions andcatalytic converter damage. For this reason, if a se-
vere misfire is detected, the fuel injector
will be turned off to
the specific cylinder and the
MIL will be illuminated. A misfire
may also produce an overheated catalytic converter, which
can be a fire hazard.
Oscilloscope diagnostic diagrams
One way to diagnose a faulty coil is to use an oscilloscope to
analyze spark quality with the engine running.
See Table b. lgnition secondary voltage diagnostics for
list of common ignition
coil voltage faults and related causes.

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.-
ignition System
Disabling ignition system
The ignition system operates in a lethal voltage range and
should be disabled any time engine service or repair work is
being done that requires the ignition to be switched on.
The engine management system can be disabled by remov-
ing the DME main relay. The relay is located in the electronics
box (E-box) in the left rear of the engine
compartment, be.
neath the interior microfilter housing.
CAUTION- Relay locations may
vary. Use care when identifying relays.
See
610 Electrical Component Locations.
Checking for spark
CAUTION-
If
a spark test is done incorrecth damage to the Engine Con-
trol Module
(ECM) or the ignition coils may result.
NOTE-
Spark plug replacement is covered in 020 Maintenance.
Check~ng for spark is d~fflcult on englnes wlth d~str~butorless
ignition systems.
Try removing the spark plugs and inspecting for differences between them.
A poor-firing plug may be wet with fuel and/or ~. - ~
black and sooty, but not always. If a coil is not operating, the
engine management system will electrically disable the fuel
injector to that cylinder. The key is to look for differences be-
tween cylinders.
Ignition coil assembly, testing and
replacing
C4 UTION-
Use a digital multimeter for the following tests. I
- Remove plastic engine cover from top of valve cover by pry-
ing off bolt covers and removing cover mounting bolts.
- Raise car slowly while constantly checking position of jack
and car.
- Disconnect harness connector from coil. Connect multimeter
between terminal 15
(+) in connector and ground.
4 Terminal identification are typically molded into connector. In
photo, terminals are from left to right: 1,
4a, 15.

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Ignition System
- Turn ignition on and check for battery voltage,
If battery voltage is not present,
checlt wire between termi-
nal
15 and the unloader relay. See ELE Electrical Wiring
Diagrams.
- Turn ignition off.
Remove coil and inspect coil housing for hairline
cracks or
leaking casting material. Replace any
cracked or leaking coil.
NOTE-
A leaky coil may indicate a faulty Engine Control Module
(ECM). Check ECM before installing a new coil.
CAUTION-
Note location of coilground straps before coil removal; rein-
stall in the same location.
Use a multimeter to test:
Coil primary resistance at coil terminals.
Sparlt plug connector resistance.
* Compare results to specification in Table c. lgnition coil
resistance.
Table c. Ignition coil resistance
Coil secondary
resistance
Spark plug connector:
Bosch 1 .O I( ohm t 20%
1.8 ir ohm t 20%
Component
Co~l prlmary
resistance
- Replace ignition coil or sparlt plug connector if resistance
readings do not meet specifications.
4 Remove ignition coil to be tested.
Install
BMW special tool 12 7 030 (A) on coil to be tested.
Connect ground jumper between coil mounting point
(B)
and engine ground point (C).
Clip scope high pick-up lead (D) around ignition lead.
Start engine.
Compare scope pattern with diagrams in Oscilloscope
di-
agnostic diagrams.
NOTE-
When replacing ignition coils, ensure that the replacements
Terminal
1 (-) and 15 (+)
are
from the same manufacturer with the same partlcode
numbers. If individual coils with the correct specifications are
not available. all coils should be
re~laced.
Resistance
0.8 ohms