1998 BMW 740I Owners Manual

128n
Brake system Winter operationBrake fluid level
The warning lamp for the brake
hydraulic system comes on or
the message "Check Brake
Fluid" appears in the Check
Control:
The brake fluid level is too low in the
reservoir. Refer to page 147.
If the brake fluid level is too low and
brake pedal travel has become notice-
ably longer, there may be a defect in
one of the brake system's hydraulic cir-
cuits.
The remaining circuit continues to pro-
vide adequate brake-system perfor-
mance.
Proceed to the nearest authorized
BMW center. Higher brake appli-
cation pressure may be necessary un-
der these conditions, and brake pedal
travel may be significantly longer.
Please remember to adapt your driving
style accordingly.<
The warning lamp also comes on with
the "Check Brake Pads" message in the
Check Control.
Brake padsThe message "Check Brake Pads" ap-
pears in the Check Control:
The brake pads have reached their min-
imum pad thickness. Proceed to the
nearest authorized BMW center as
soon as possible to have the pads re-
placed.
We recommend the use of original
BMW brake pads and compo-
nents, otherwise driving safety can be
impaired.<
The onset of winter is often accompa-
nied by rapid changes in weather. Ad-
aptations in driving style should be ac-
companied by preparations on the
vehicle itself to ensure that your vehicle
operation through the winter remains
safe and trouble-free.CoolantBe sure that the coolant mixture is kept
at the year-round ratio of 50:50 (water
and antifreeze/corrosion protection).
This mixture provides protection
against freezing down to approx. –347
(–376). Replace the coolant every four
years.LocksBMW door lock deicer can be used to
free the locks if they are frozen. This
deicer also contains lubricant.
After using deicer, treatment with BMW
lock barrel grease is recommended.

129n
RepairsIndexOverview Controls Car care Technology Data
Winter operationRubber seals and componentsIn order to prevent the weather-strip-
ping from freezing, apply rubber treat-
ment or a silicone spray to the seals on
the doors, hood and luggage compart-
ment lid.
A full range of car care products is
available from your BMW center.< Snow chainsBMW snow chains
* can be fitted on
both summer and winter tires in re-
sponse to severe winter road condi-
tions. Mount them in pairs on the rear
wheels only, and be sure to comply with
the manufacturer's safety instructions.
Do not exceed a maximum speed of
30 mph (50 km/h). In this situation
(snow chains mounted), deactivate the
ASC+T or DSC
*. Refer to page 92.
Starting offWhen starting off in deep snow or when
rocking the car to free it, we recom-
mend that you switch the ASC+T or
DSC
* off. Refer to page 92.
Driving on low-traction road
surfacesUse smooth, gentle pressure to control
the accelerator pedal. Avoid excessive
engine speeds and shift to the next
higher gear at an early point. Adapt
your speed and driving style when ap-
proaching grades. Maintain an ade-
quate distance between yourself and
the car ahead.BrakesWinter road conditions substantially re-
duce the amount of traction available
between the tires and the road surface;
the resulting increases in braking dis-
tance are considerable and should be
continually borne in mind.
ABS is intended to prevent the wheels
from locking during brake applications,
thus helping to maintain vehicle stability
and steering response. If the ABS does not respond in a critical
braking situation and the wheels lock:
Reduce the pressure on the brake
pedal until the wheels just start to roll
again while still maintaining enough
force to continue braking.
Following that, increase pedal pressure
again. Reduce the pressure as the
wheels lock, then reapply pressure, etc.
This type of staggered braking will re-
duce the braking distance, and the ve-
hicle still remains responsive to steer-
ing.
You can then attempt to steer around
hazards after you have reduced pres-
sure on the brake pedal.
Do not shift down on slick road
surfaces. Doing so could cause
the rear wheels to lose traction and
skid, which could result in the loss of
vehicle control.<

130n
Winter operation Power steering Level control system
*
Skid controlRelease the accelerator pedal. Coun-
tersteer carefully and attempt to regain
control of the vehicle.ParkingPlace the selector lever in position P
(Park). Engage the parking brake when
parking on hills and inclined surfaces. In
order to prevent the parking brake lin-
ings from locking in the drum due to
frost or corrosion, dry them by gently
applying the parking brake as the vehi-
cle is coming to a stop. Make sure that
following traffic is not endangered.
The brake lamps do not come on
when the parking brake is ap-
plied.<
High steering effort:
Check the fluid level. Refer to
page 148.
High steering effort during sudden tran-
sitions:
Consult your authorized BMW center
immediately for an inspection.Servotronic special
*
If steering becomes lighter as speed in-
creases:
Malfunction in the electronic control
system. Have your BMW center inspect
this system as soon as possible.
If the power steering fails, in-
creased effort will be required to
steer the vehicle.<
If the message "LEVEL CONTROL IN-
ACTIVE" appears in the Check Control,
there is a malfunction in the level con-
trol system.
Stop and inspect the vehicle. If it is
riding significantly lower in the rear
than in the front, or if it is sitting at an
incline (left rear compared to right rear),
consult the nearest authorized BMW
center. Drive with appropriate caution
in the meantime. The vehicle has re-
duced ground clearance or driving
comfort is noticeably reduced.
Even if the attitude of the vehicle is nor-
mal, you should consult the nearest au-
thorized BMW center if the warning
lamp indicates a system fault.

131n
RepairsIndexOverview Controls Car care Technology Data
Cellular phone Radio receptionMobile communications systems (cellu-
lar phone, radio, etc.) are permitted with
an output up to 10 watts only. Even
these systems may trigger malfunctions
in the operation of your vehicle if they
are not specifically designed for use
with the vehicle. BMW can neither test
nor assume responsibility for every indi-
vidual product being offered on the
market. We recommend that you con-
sult your BMW center before purchas-
ing any device of this kind.
To ensure that your BMW continues to
provide reliable and trouble-free opera-
tion, refrain from using a cellular phone
or other radio device with an antenna
located inside the passenger compart-
ment. The antenna should always be
mounted on the outside of the vehicle.
Before loading the vehicle on a
car-carrier train or driving it
through a car-wash, remove the an-
tenna.<
The reception and sound quality ob-
tained from mobile radios varies ac-
cording to a variety of factors, including
the broadcast range of the transmitter
and the directional orientation of the
antenna. Interference factors such as
high-tension power lines, buildings and
natural obstructions can all lead to un-
avoidable reception interference, re-
gardless of how well the vehicle sound
system is operating.
Climatic factors such as intense solar
radiation, fog, rain and snow can also
interfere with reception.
Cellular phones without official BMW
approval can also generate interfer-
ence. This phenomenon assumes the
form of a low-pitched hum emanating
from the speaker system.
Please refer to the supplementary oper-
ating instructions provided with your
sound system for detailed information
on its use.

132n
Tire inflation pressure Tire conditionInformation for your safetyThe factory-approved radial tires are
matched to the car and have been se-
lected to provide optimum safety and
driving comfort on your car.
It is not merely the tire's service life, but
also driving comfort and - above all else
- driving safety which depend on the
condition of the tires and the mainte-
nance of the specified tire pressure.
Incorrect inflation pressure is a frequent
cause of tire damage. They also influ-
ence the roadholding ability of your
BMW.
Check tire inflation pressures – in-
cluding the spare tire – regularly,
at least every two weeks and before be-
ginning a longer trip. If this is not done,
incorrect tire pressures can cause driv-
ing instability and tire damage, ulti-
mately resulting in accidents.<
Tire tread
– tire damage
Inspect your tires frequently for tread
wear, signs of damage and for foreign
objects lodged in the tread. Check the
tread depth.
Tread depth should not be allowed to
go below 0.12 in (3 mm), even though
the legally specified minimum tread
depth is only 0.063 in (1.6 mm). Wear
indicators appear in the tread at 0.063 in
(1.6 mm) to indicate that the legally per-
missible wear limit has been reached.
Below 0.12 in (3 mm) tread depth, there
is an increased risk of aquaplaning,
even at relatively moderate speeds and
with only small amounts of water on the
road.390de331
Do not drive on a deflated (flat)
tire. A flat tire greatly impairs
steering and braking response, and can
lead to complete loss of control over
the vehicle.
Avoid overloading the vehicle so that
the permitted load on the tires is not ex-
ceeded. Overloading can lead to over-
heating and increases the rate at which
damage develops inside the tires.
The ultimate result can assume the form
of a sudden air loss.
Unusual vibrations encountered during
normal vehicle operation can indicate
tire failure or some other vehicle defect,
as can variations in normal vehicle re-
sponse, such as a pronounced ten-
dency to pull to the left or right. Should
this occur, respond by immediately re-
ducing your speed and carefully pro-
ceeding to the nearest BMW center or
professional tire center, or having the
vehicle towed in to have it and its tires
inspected.
Tire damage (up to and including blow-
outs) can endanger the lives of both the
vehicle occupants and other road
users.<

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RepairsIndexOverview Controls Car care Technology Data
Tire replacement Tire rotationTo maintain good handling and vehicle
response, use only tires of a single
tread configuration from a single manu-
facturer. BMW tests and approves
wheel/tire combinations. Refer to
page 136.
Do not use retreaded tires, since
driving safety may be impaired by
their use. This is due to the possible
variations in casing structures and, in
some cases, to their extreme age,
which can lead to a decrease in their
durability.< Tire ageThe date on which the tire was manu-
factured is indicated by the code on the
sidewall:
DOT ... 178 means that the tires were
manufactured in the 17th week of 1998.
BMW recommends the replacement of
all tires when the tires are no more than
6 years old, even if a tire life of 10 years
is possible.
Spare tires over 6 years old should be
used only in case of emergency. Such a
tire should be replaced by a new tire
immediately, and should not be
mounted together with new tires.
Between the axlesThe tread wear patterns at the front end
differ from those at the rear - the actual
patterns will vary according to individ-
ual driving conditions. In the interests of
safety and maintaining optimal handling
characteristics, tire rotation is not rec-
ommended.
If a proposed interaxle rotation of tires
is based on economic considerations,
one should consider whether the costs
for the rotation are likely to be recap-
tured by any increase in the service life
of the tires which might be realized. Ro-
tation should always be carried out at
short intervals, with a maximum of
3,000 miles (5,000 km). Consult your
authorized BMW center for more infor-
mation.
Should you decide to rotate the tires, it
is essential to comply with the follow-
ing:
Rotate tires on the same side only,
since braking characteristics and road
grip could otherwise be adversely af-
fected.
Following rotation, correct the tire infla-
tion pressure.If different tire sizes are mounted
on the front and rear axles
(page 136), the tires may not be rotated
from one axle to the other.<

134n
Wheel and tire combinationsThe right choiceUse only tires approved by BMW. Refer
to page 136.
Because of the high speeds this vehicle
can reach, the use of specific tire
brands, specifications and dimensions
is mandatory. Consult any BMW center
for details.
Comply with national, state, or provin-
cial regulations.
The correct wheel-tire combina-
tion affects different systems such
as ABS, ATC, ASC+T/DSC. The func-
tion of these systems is impaired if im-
proper wheel-tire combinations are
used.
For this reason, use only tires of the
same brand and tread pattern. In the
event of a flat tire if you have mounted
winter tires, for example, remount the
approved wheel-tire combination as
soon as possible.<
Codes on tires and wheelsThe tire codes will aid you in selecting
the correct tire.
Codes on radial tires:
The speed rating indicates the ap-
proved maximum speed for the tire.
Summer tires:
S = up to 112 mph (180 km/h)
T = up to 118 mph (190 km/h)
H = up to 130 mph (210 km/h)
V = up to 149 mph (240 km/h)
W = up to 167 mph (270 km/h)
ZR = over 149 mph (240 km/h) For example
Nominal width
in mm
Aspect ratio in %
Radial tire code
Rim diameter in inches
Load rating
(not on ZR tires)
Speed rating
(before R on ZR tires)
235/60 R 16 100 W
Winter tires:
Q M+S = up to 100 mph (160 km/h)
T M+S = up to 118 mph (190 km/h)
H M+S = up to 130 mph (210 km/h)
Codes stamped on light-alloy wheels:
Protect valve inserts against dirt using
screw-on valve stem caps. Dirt in the
valves frequently leads to slow leaks.For example
Rim width
in inches
Code letter for
flange type
Symbol for full-drop
center rim
Rim diameter in inches
Hump on the 2 rim shoulders
71/2 x 16 H 2
J

135n
RepairsIndexOverview Controls Car care Technology Data
Winter tires Snow chains
*
Choosing the right tireBMW recommends winter tires (M+S
radial tires) for driving in adverse winter
road conditions. While tires known as
all-season tires (M+S designation) pro-
vide better winter traction than summer
tires with load ratings H, V, W and ZR,
they generally do not achieve the per-
formance of winter tires.
In the interests of sure tracking and safe
steering response at all four wheels,
mount winter tires which are made by
the same manufacturer and which have
the same tread configuration.
Mount only winter tires which have
been approved by BMW. Any BMW
center will be glad to provide you with
information on the best winter tires for
your particular driving conditions.
Do not exceed specified
maximum speeds
Never exceed the maximum
speed for which the tires are
rated.
Unprofessional attempts by laymen to
service tires can lead to damage and
accidents.
Have this work performed by skilled
professionals only. Any BMW center
has the required technical knowledge
and the proper equipment and will be
happy to assist you.<
Tire condition, tire pressureWinter tires display a perceptible loss in
their ability to cope with winter driving
conditions once the tread wears to be-
low 0.16 in (4 mm), and should thus be
replaced.
Comply with the specified tire inflation
pressures - and be sure to have the
wheel and tire assemblies balanced ev-
ery time you change the tires.StorageStore tires in a cool, dry place, away
from light whenever possible. Protect
the tires against contact with oil, grease
and fuel.
Use narrow-link BMW snow chains on
summer or winter tires only in pairs and
only on the rear wheels. Comply with all
manufacturer's safety precautions when
mounting the chains.