1999 BMW 540i Oul

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I Fuel Tank and Fuel Pump
- Expose right side access cover:
Peel forward lip of carpet.
Release rubber grommet from center of access cover insu-
lation.
Peel back insulation at
perforations to expose fuel tank ac-
cess cover.
Remove right side cover to expose electrical harness con-
nector.
WARNING -
Fuel may be spilled. Do not smolce or work near heaters or
other fire hazards.
When disconnecting fuel hose, wrap shop rag around
end of hose to prevent spray of fuel under pressure.
Remove
tank sending unit:
Release electrical harness by sliding lock back, then lifting
off connector.
a Disconnect hose (arrow).
Unscrew threaded collar from fuel
pumpifuel level sender.
NOTE-
BMW special spanner 16 1 020 should be used to remove
and install the threaded collar. Damage to the collar may re-
sult if the special tool is not used.
Slowly withdraw assembly from tank, allowing fuel to drain
off. If necessary, push level sender arm toward sending
unit to facilitate removal.
CAUTION-
Do not bend fuel level sender arm.
To remove fuel pump, press locking tabs (arrows) towards
pump body.
Lifl out pump, using care not to damage hoses.

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/ ~uel Tank and Fuel Pump
4 Remove tank sending unit:
Disconnect electrical harness connector.
Disconnect hose (arrow).
- Unscrew threaded collar from fuel level sender.
NOTE-
BMW special spanner 16 1 020 should be used to remove
and install the threaded collar. Damage to the collar may
result if the special tool is not used.
Slowly withdraw assembly from tank, allowing fuel to drain
off. If necessary, push level sender arm toward sending
unit to facilitate removal.
CA UTIOW-
Do not bend fuel level sender arm.
4 Once level sensor unit has been lifted partially out of tank,
disconnect tank siphon hose by pressing tabs (arrows).
- Installation is reverse of removal
Attach tank siphon hose to sender unit firmly.
Use new sealing ring at tank collar.
. Be sure that fuel sender float points in same direction as
during removal.
- Reconnect harness connector.
Fill tank and
check for leaks by running engine.
CAUTION-
After finishing repairs but before starting engine, be sure
there is at least
5 liters (1.5gallons) of fuel in tan/(. The fuel
pump will be damaged if run without fuel.
Tightening
torque
Tank collar loclting rlng to tanlt 35 Nm (26 lb-ft) -

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--
I Fuel Tank and Fuel Pump
The plastic fuel tank is mounted underneath the center of the
car (underneath the rear seat). Mounted in the fuel tank are
the fuel pump and fuel level sending units. Connecting lines
for the evaporative emission control system and expansion
tank are also attached to the tank.
Fuel
tank capacity for E39 models
Tank capacity
70 liters (18.5 gal)
Reserve capacity
8 liters (2.1 gal)
Fuel tank, draining
Drain fuel tank into a safe storage unit using an approved fuel
pumping device.
WARNING-
# Before removing tank, be sure that all hot components,
such as the exhaust system, are completely cooled down.
Fuel may be spilled. Do not smoke or
work near heat-
ers or other fire hazards.
- Start engine and allow to run 10 - 15 seconds to fill fuel com-
pensating siphon assembly. This will allow both lobes of fuel
tank to he drawn off through fuel filler pipe,
- Disconnect negative cable from battery.
CAUTION-
Prior to disconnecting the batteg read the battery discon-
nection cautions given
in 001 General Warnings and Cau-
tions.
- Remove fuel tank filler cap
- Slide suction hose into filler neck about 130 cm (51 in.), twist-
ing as necessary. Withdraw fuel into storage unit.
- Monitor fuel level reduction in both lobes:
- Remove rear seat cushion and access both fuel tank send-
er harness connectors.
Use multimeter to measure resistance at both senders,
Resistance should drop as fuel level drops.
- If siphoning mechanism is faulty, drain left tank lobe sepa-
rately by removing sender cover and pumping fuel directly
out of left lobe.

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160-22
Fuel Tank and Fuel Pump
4 Working underneath car, pinch off supply and return fuel hos-
es (arrows), then disconnect hoses from rigid metal lines.
- Remove right rear wheel and wheel housing splash shield.
4 Worlting at right rear wheel housing, loosen hose clamp
(arrow) and disconnect filler pipe from tank.
- Support tank from below. Remove tank strap mounting bolts.
Lower and remove tank, disconnecting right side vent and
other
hoses/electrical connectors as necessary.
Always use new seals, gaskets, O-rings, and hose clamps.
lnspect hoses and replace any that are chafed,
dr~ed out or
cracked.
lnspect heat shield and replace if corroded.
Inspect rubber buffers and
hers on fuel tank, support
straps and on underside of body. Replace rubber parts that
are hardened or damaged.
- After finishing repairs but before starting engine, fill fuel tank
with at least
5 liters (1.5 gallons) of fuel.
CAUTlOI+
The fuelpump will be damaged if run without fuel.
* If the filler neck has been removed from the body, be
sure to reattach the
neck grounding screw (where ap-
plicable). Check electrical resistance between the
ground tab and wheel
hub. The resistance should be
no
hiaher than 0.6f2
Tightening torques
Fuel tank to body 23 Nm (17 ft-lb)
Hose clamp
8 -13 mm dia. 2 Nm (18 in-lb)
Hose clamp 13
- 16 mm dia. 3 Nm (27 in-lb)
Hose clamp 42
- 48 mm dia. 4 Nm (36 in-lb)

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Radiator and Cooling System
Check for cloggedlplugged radiator or coolant passages.
Cooling system pressure test
A cooling system pressure tester is used to test for coolant
leaks, including internal ones. Common sources of internal
coolant leaks are a faulty cylinder head gasket, a
craclted cyl-
inder head, or a cracked engine block.
WARNING-
At normal operating temperature the cooling system is pres-
surized. Allow the system to cool before opening. Release
the cap slowly to allow safe release ofpressure.
4 With engine cold, install pressure tester (BMW special tools
17 0 002117 0 005 or equivalent) to expansion tank. Pressur-
ize system to specification listed in Table a. Cooling system
test pressures.
Pressure should not drop more than 0.1 bar (1.45 psi) for
at least two minutes.
. If pressure drops rapidly and there is no sign of external
leakage, cylinder head gasket may be faulty. Perform com-
pression and leak-down tests.
Test expansion
tank cap using pressure tester with correct
adapter (BMW special tool 17
0 007 or equivalent). Re-
place faulty cap or cap gasket.
Table a. Cooling system test pressures
0021663 I Component l~est pressure
Radiator
11.5 bar (21.75 psi)
Radiator cap
12 bar (29 psi)
CAUTION-
Exceeding the specified test pressure could damage the ra-
diator or other svstem
com~onents.

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180-2
Exhaust System
The exhaust system is designed to be maintenance free, al-
though regular inspection is warranted due to the harsh oper-
ating conditions. Under normal conditions, the catalytic
converter does not require replacement unless it is damaged.
New fasteners, clamps, rubber mounts and gaskets should
be used when replacing exhaust components.
A liberal appli-
cation of penetrating oil to the exhaust system nuts and bolts
in advance may make removal easier.
WARNING -
The exhaust system and catalytic converter operate at
very high temperatures. Allow components to cool before
servicing. Wear protective clothing to prevent burns.
Do not use flammable chemicals near a hot
cataiyiic
converter.
Corroded exhaust system components crumble easily
and often have exposed sharp edges. To avoid injury,
wear eye protection and heavy gloves when working
Exhaust system, removing and installing
The removal and installation procedures given here are gen-
eral procedures for all models. The removal of the exhaust
system as a complete unit is recommended. Once the com-
plete system is removed from the car, individual pipes and
mufflers can be more easily replaced.
WARNING-
Exhaust gases are colorless, odorless, and very toxic. Run
the engine only in a well-ventilated area. Immediately repair
any
leaks in the exhaust system or structural damage to the
car body that
might allow exhaust gases to enter the passen-
ger compartment.
CAUTION-
Use care not to drag or bang oxygen sensors. Oxygen sen-
sors can be easily ruined.

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... .
Exhaust System
- With exhaust system fully cold, raise and support car for ac-
cess to exhaust system.
WARNING -
Do not worlc under a lifted car unless it is solidly supported on
jack stands designed for that purpose. Never work under a
car that is supported solely by a
jack.
- Disconnect oxygen sensor connector(s).
4 Loosen and remove bolts holding front exhaust pipes to ex-
haust manifolds (arrows). Right side of
V8 model shown.
- Support exhaust system
- Where applicable, disconnect exhaust support bracket as-
sembly from transmission.
< Remove hangers by prying off bracket (arrows).
- Lower exhaust system as a single unit to ground.
NOTE-
If the catalytic converterlfront exhaust pipe assembly is to be
replaced, transfer the oxygen sensors to the new
pipe(s).
Tightening torque
Oxygen sensor
55 Nm (41 ft-lb)
- installation is reverse of removal.
* Make sure there is at least 20 mm (314 in.) clearance be-
tween exhaust system and car body at every point.
Loosely install
ail exhaust system mounting hardware and
hangers before tightening fasteners to their final torque.
Coat manifold studs with copper paste before installing
nuts.
NOTE-
Where applicable, tighten front pipe with semi-flexible com-
pensator last when installing front pipe to
manifolds.
Tightening torques
Exhaust manifolds
to cylinder head 22 Nm (1 7 It-lb)
Front exhaust pipe to manifolds 30 Nm (22 ft-lb)
To prevent exhaust system rattles and vibration, the system
should be slightly preloaded by pushing the rear clamping
brackets forward about 7 mm (114 in).

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/Exhaust System Muffler, replacing
BMW offers individual mufflers as replacement parts for the
original one-piece assembly. Replacement of a rear muffler
may be possible with the system installed on the car. Re-
placement of the front or middle muffler should only be done
with the exhaust removed from the car.
< Mark length of new muffler pipe(s) on old system.
- Use exhaust pipe cutter to cut pipe(s). Deburr cut pipe
end@).
4 Use clamping sleeves to join new pipe(s) to old.
Make sure pipe ends are centered inside sleeve.
Point clamping sleeve bolt threads
(arrows) down.
- Reinstall exhaust system.