engine MERCEDES-BENZ R-Class 2011 W251 Repair Manual

too low. Observe additional warning
messages in the multifunction display.
The brake fluid level may be too low due to
brake pad wear or leaking brake lines.
Have the brake system checked
immediately. This work should be carried
out at an authorized Mercedes-Benz
Center.
All checks and maintenance work on the
brake system must be carried out at a
qualified specialist workshop. Contact an
authorized Mercedes-Benz Center.
Only install brake pads and use brake fluid
recommended by Mercedes-Benz.GWarning
If other than recommended brake pads are
installed, or other than recommended brake
fluid is used, the braking properties of the
vehicle can be degraded to an extent that safe
braking is substantially impaired. This could
result in an accident.
! A function or performance test may only
be carried out on a two-axle dynamometer.
If you are planning to have the vehicle
tested on such a dynamometer, contact an
authorized Mercedes-Benz Center to
obtain further information first. Otherwise,
the drive train or the brake system may
suffer damage.
! As the ESP ®
system operates
automatically, the engine and the ignition
must be switched off (SmartKey in position
0 or 1 in the ignition lock or Start/Stop
button in position 0 or 1) while the parking
brake is being tested on a brake
dynamometer (maximum 10 seconds).
Braking maneuvers triggered automatically
by ESP ®
may seriously damage the brake
system.
If your brake system is only subjected to
moderate loads, you should regularly test
your brake system's function by forcefully
depressing the brake pedal when driving at
high speed. This also improves the brake
pads' friction.GWarning
Make sure that you do not endanger other
road users when you apply the brakes.
You can find a description of Brake Assist
(BAS) on ( Y page 68).
Parking brake
If you drive on wet roads or dirt-covered
surfaces, road salt and/or dirt could get into
the parking brake.
In order to prevent corrosion and a reduction
in the braking power of the parking brake,
observe the following:
R gently depress the parking brake from time
to time before beginning the journey.
R drive approximately 110 yd (100 m)
without exceeding a speed of 12 mph
(20 km/h).
GWarning!
While performing this procedure please
assure that the vehicle is stopped before
applying the parking brake. Otherwise the
rear wheels could lock up. You could lose
control of the vehicle and cause an accident.
In addition, the vehicle’s brake lights do not
light up when the parking brake is engaged.
Make sure not to endanger any other road
users when you engage the parking brake.
Driving on wet roads
Hydroplaning
If water has accumulated to a certain depth
on the road surface, there is a danger of
hydroplaning occurring, even if:
R you drive at low speeds
R the tires have adequate tread depth
Driving tips171Driving and parkingBA 251 USA, CA Edition A 2011; 1; 3, en-USd2sboikeVersion: 3.0.3.52010-04-16T14:31:55+02:00 - Seite 171Z

For this reason, in the event of heavy rain or
in conditions in which hydroplaning can occur
you must drive in the following manner:
R Lower your speed
R Avoid ruts
R Brake carefully
Driving on flooded roads
! Do not drive through flooded areas.
Check the depth of any water before driving
through it. Drive slowly through standing
water. Otherwise, water may enter the
vehicle interior or the engine compartment.
This can damage the electronic
components in the engine or the automatic
transmission. Water can also be drawn in
by the engine's air suction nozzles and this
can cause engine damage.
Prevent water from entering the vehicle
interior or engine compartment. If you have
to drive through standing water, please note
that:
R the maximum permissible still water depth
is 10 in. (25 cm).
R you should drive no faster than at walking
pace.
i Vehicles with the AIRMATIC package:
if you have set the raised vehicle level
before driving through standing water, the
maximum water depth is 12 in. (30 cm).
Winter driving
General notes
Have your vehicle winterproofed at a qualified
specialist workshop, e.g. at an authorized
Mercedes-Benz Center, at the onset of
winter.
Observe the notes in the "Winter operation"
section ( Y page 172).
i Vehicles with a diesel engine: do not
cover the radiator, e.g. with a protective
cover. The measuring function of the
Onboard Diagnosis System may otherwise
provide inaccurate values. Some of these
values are required by law and must
therefore always be accurate.
Slippery road surfacesGWarning
If the vehicle becomes stuck in snow, make
sure snow is kept clear of the exhaust pipe
and from around the vehicle with the engine
running. Otherwise, deadly carbon monoxide
(CO) gases may enter vehicle interior
resulting in unconsciousness and death.
To assure sufficient fresh air ventilation, open
a window slightly on the side of the vehicle
not facing the wind.
GWarning!
The outside temperature indicator is not
designed to serve as an ice-warning device
and is therefore unsuitable for that purpose.
Indicated temperatures just above the
freezing point do not guarantee that the road
surface is free of ice. The road may still be icy,
especially in wooded areas or on bridges.
GWarning
On slippery road surfaces, never downshift in
order to obtain braking action. This could
result in drive wheel slip and reduced vehicle
control. Your vehicle's ABS will not prevent
this type of loss of control.
You should drive particularly carefully on
slippery road surfaces. Avoid sudden
acceleration, steering and braking
maneuvers. Do not use cruise control.
If the vehicle threatens to skid or cannot be
stopped when moving at low speed:
XShift the transmission to position N.
i
For more information on driving with
snow chains, see .
172Driving tipsDriving and parking
BA 251 USA, CA Edition A 2011; 1; 3, en-USd2sboikeVersion: 3.0.3.52010-04-16T14:31:55+02:00 - Seite 172

GWarning
Make sure that you do not endanger other
road users when you apply the brakes.
Driving abroad
An extensive Mercedes-Benz Service network
is also available in other countries. The
Service Hotline's current telephone numbers
for use when you are abroad are to be found
in the "Service24h" section of the Service
Booklet.
Driving systems
Cruise control
Important safety guidelines
Cruise control maintains a constant road
speed for you. It brakes automatically in order
to avoid exceeding the set speed. On long and
steep downhill gradients, especially if the
vehicle is laden or towing a trailer, you must
select shift range 1, 2 or 3 in good time. By
doing so, you will make use of the braking
effect of the engine, which relieves the load
on the brake system and prevents the brakes
from overheating and wearing too quickly.
Use cruise control only if road and traffic
conditions make it appropriate to maintain a
steady speed for a prolonged period. You can
store any road speed above 20 mph
(30 km/h).
GWarning
The cruise control is a convenience system
designed to assist the driver during vehicle
operation. The driver is and must always
remain responsible for the vehicle's speed
and for safe brake operation.
Only use the cruise control if the road, traffic,
and weather conditions make it advisable to
travel at a constant speed.
R The use of the cruise control can be
dangerous on winding roads or in heavy
traffic because conditions do not allow safe
driving at a constant speed.
R The use of the cruise control can be
dangerous on slippery roads. Rapid
changes in tire traction can result in wheel
spin and loss of control.
R Deactivate the cruise control when driving
in fog.
The "Resume" function should only be
operated if the driver is fully aware of the
previously set speed and wishes to resume
this particular preset speed.GWarning
When cruise control brakes, the brake pedal
is pulled back (i.e. operated automatically).
The area around the pedal must not be
blocked by obstacles:
R Do not place any objects in the footwell.
R Ensure that floormats and carpets are fixed
securely. In particular, do not place several
floormats on top of one another.
R Do not place your foot under the brake
pedal, as it could become trapped.
Non-compliance could lead you to cause an
accident in which you and/or others could be
seriously injured.
Cruise control lever
:To store the current speed or a higher
speed;To store the current speed or a lower
speedDriving systems173Driving and parkingBA 251 USA, CA Edition A 2011; 1; 3, en-USd2sboikeVersion: 3.0.3.52010-04-16T14:31:55+02:00 - Seite 173Z

Setting in 5 mph (Canada: 10 km/h)
incrementsXBriefly press the cruise control lever
beyond the pressure point, up : for a
higher speed or down ; for a lower speed.
The last speed stored is increased or
reduced.
Deactivating cruise control
There are several ways to deactivate cruise
control:
XBriefly press the cruise control lever
forwards =.
or
XBrake.
Cruise control is automatically deactivated if:
R you depress the parking brake.
R you are driving below 20 mph (30 km/h).
R ESP ®
intervenes or you deactivate ESP ®
.
R you shift the transmission to position N
while driving.
If cruise control is deactivated, you will hear
a warning tone. You will see the Cruise
control Off message in the multifunction
display for approximately five seconds.
i The last speed stored is cleared when you
switch off the engine.
DISTRONIC
Important safety guidelines
DISTRONIC regulates the speed and
automatically helps you maintain the
distance to the vehicle detected in front. It
brakes automatically in order to avoid
exceeding the set speed.
On long and steep downhill gradients,
especially if the vehicle is laden or towing a
trailer, you must select shift range 1, 2 or 3
in good time. By doing so, you will make use
of the braking effect of the engine, which
relieves the load on the brake system and
prevents the brakes from overheating and
wearing too quickly.
If a slower-moving vehicle is detected in front,
DISTRONIC causes your vehicle to brake and
maintain the preset distance to the vehicle in
front.GWarning!
The Distronic requires familiarity with its
operational characteristics. We strongly
recommend that you review the following
information carefully before operating the
system.
GWarning
When DISTRONIC brakes, the brake pedal is
pulled back (i.e. operated automatically). The
area around the pedal must not be blocked by
obstacles:
R do not place any objects in the footwell.
R ensure that floormats and carpets are fixed
securely. In particular, do not place several
floormats on top of one another.
R do not place your foot under the brake
pedal, as it could become trapped.
Non-compliance could lead you to cause an
accident in which you and/or others could be
seriously injured.
GWarning!
The Distronic is a convenience system. Its
speed adjustment reduction capability is
intended to make cruise control more
effective and usable when traffic speeds vary.
It is not however, intended to, nor does it,
replace the need for extreme care.
The responsibility for the vehicle’s speed,
distance to the preceding vehicle and, most
importantly, brake operation to ensure a safe
stopping distance, always remains with the
driver.
The Distronic cannot take street and traffic
conditions into account. Complex driving
situations are not always fully recognized by
the Distronic. This could result in wrong or
missing distance warnings.
Driving systems175Driving and parkingBA 251 USA, CA Edition A 2011; 1; 3, en-USd2sboikeVersion: 3.0.3.52010-04-16T14:31:55+02:00 - Seite 175Z

Switch off the Distronic
R when changing from the left to the right
lane if vehicles are moving more slowly in
the left lane
R when entering a turn lane or highway off
ramp
R in complex driving situations, such as in
highway construction zones
In these situations, the Distronic will continue
to maintain the set speed unless deactivated.
The Distronic is designed and intended only
to maintain a set speed and keep a set
distance from moving objects in front of it.
i This device has been approved by the FCC
as a "Vehicular Radar System". The radar
sensor is intended for use in an automotive
radar system only. Removing, tampering
with, or altering the device will void any
warranties, and is forbidden by the FCC. Do
not tamper with, alter or use in any non-
approved way.
Any unauthorized modification to this
device may invalidate the vehicle's general
operating permit.
Cruise control lever:To store the current speed or a higher
speed;To store the current speed or a lower
speed=To deactivate DISTRONIC?To store the current speed or to call up
the last stored speedActivating DISTRONIC, storing and
maintaining the current speedGWarning!
The vehicle can be braked when DISTRONIC
is activated. For this reason, deactivate
DISTRONIC if the vehicle is to be set in motion
by other means (e.g. in a car wash or by
towing).
You can activate DISTRONIC in the following
circumstances:
R if the engine has been started and you have
been driving for up to two minutes
R while driving, except if you brake
R if the parking brake is not applied
R if ESP ®
is activated
R if the transmission is in position D
Activating while driving
When driving at speeds below 20 mph
(30 km/h) , you can only activate DISTRONIC
PLUS if the vehicle in front has been detected
and is shown in the multifunction display. If
the vehicle in front is not shown in the
multifunction display and is no longer being
detected, because it has changed lanes, for
example, DISTRONIC is deactivated and you
hear a warning tone.
XBriefly pull the cruise control lever towards
you ? or press it up : or down ; to the
pressure point.
DISTRONIC is activated.XKeep the cruise control lever pressed
up : or down ; until the desired speed
is set.XRemove your foot from the accelerator
pedal.
Your vehicle adapts its speed to that of the
vehicle in front, but only up to the desired
stored speed.
i You can use the cruise control lever to set
the stored speed and the thumbwheel on
the cruise control lever to set the specified
minimum distance ( Y page 179).
Driving systems177Driving and parkingBA 251 USA, CA Edition A 2011; 1; 3, en-USd2sboikeVersion: 3.0.3.52010-04-16T14:31:55+02:00 - Seite 177Z

Deactivating DISTRONIC
There are a number of ways to deactivate
DISTRONIC:
XBriefly press the cruise control lever
forwards :.
or
XBrake.
iThe last speed stored remains stored until
you switch off the engine.
iDISTRONIC is not deactivated if you
depress the accelerator pedal. If you
accelerate to overtake, DISTRONIC adjusts
the vehicle's speed to the last speed stored
after you have finished overtaking.
DISTRONIC is automatically deactivated if:
Ryou apply the parking brake.
Ryou are driving slower than 20 mph
(25 km/h) and there is no vehicle in front,
or if the vehicle in front is no longer
detected.
RESP® intervenes or if you deactivate ESP®.
Ryou shift the transmission to P, R or N.
If DISTRONIC is deactivated, you will hear a
warning tone. You will see the DISTRONIC
Off message in the multifunction display for
approximately five seconds.
Tips for driving with DISTRONIC
The following contains descriptions of certain
road and traffic conditions in which you must
be particularly attentive. In such situations,
brake if necessary. DISTRONIC is then
deactivated.
GWarning!
The Distronic works to maintain the speed
selected by the driver unless a moving
obstacle proceeding directly ahead of it in the
same travel direction is detected (e.g.
following another vehicle ahead of you at your
set distance).
This means that:
RYour vehicle can pass another vehicle after
you have changed lanes.
RWhile in a sharp turn or if the preceding
vehicle is in a sharp turn, the Distronic
could lose sight of the preceding vehicle.
Your vehicle could then accelerate to the
previously selected speed.
The Distronic regulates only the distance
between your vehicle and those directly
ahead of it, but does not register stationary
objects in the road, e.g.:
Ra stopped vehicle in a traffic jam
Ra disabled vehicle
Ran oncoming vehicle
The driver must always be alert, observe all
traffic and intercede as required by means of
steering or braking the vehicle.
GWarning!
The Distronic should not be used in snowy or
icy road conditions.
Cornering, going into and coming out of a
bend
Driving systems181Driving and parkingBA 251 USA, CA Edition A 2011; 1; 3, en-USd2sboikeVersion: 3.0.3.52010-04-16T14:31:55+02:00 - Seite 181Z

Observe the notes on driving with a trailer
( Y page 193).
AIRMATIC package
General notes
AIRMATIC enables a suspension tuning
setting to be selected and regulates the
damping behavior and level of your vehicle.
The system comprises two components: ADS
(Adaptive Damping System) ( Y page 183)
and level control ( Y page 183) .
Observe the notes on driving with a trailer
( Y page 193).
ADS (Adaptive Damping System)
ADS is continuously electronically controlled.
It adapts the damping characteristics to the
operating and driving situation. Damping is
controlled separately for each wheel. This
increases driving safety and tire comfort.
This depends on:
R your driving style
R the road surface conditions
R the ADS setting
R the vehicle level setting
Your selection remains stored even if you
remove the key from the ignition lock.
You can choose between the following ADS
settings:
R AUTO for normal driving situations;
indicator lamps ; and = are off.
R SPORT for sporty driving; indicator
lamp ; is on.
R COMF for a more comfortable ride;
indicator lamp = is on.XStart the engine.XPress button : repeatedly until the
desired setting is selected.
Level control
Level control automatically adapts the vehicle
level to the current operating and driving
situation. This results in reduced fuel
consumption and improved handling.
Make changes to the vehicle level while the
vehicle is in motion. This enables the vehicle
to adjust to the new level as quickly as
possible.
The vehicle level may change visibly if you
park the vehicle and the outside temperature
changes. If the temperature drops, the
vehicle level is lower; with an increase in
temperature, the vehicle level rises.
When you unlock the vehicle or open a door,
the vehicle begins to balance the load
discrepancies while still parked. However, for
significant level changes, e.g. after the
vehicle has been stationary for a long period,
the engine must be on. For safety reasons,
the vehicle is only lowered when the doors are
closed. Lowering is interrupted if a door is
opened and continues once the door has
been closed.
GWarning!
Make sure no one is near the wheel housing
or under the vehicle when you lower the
vehicle while it is standing still. Limbs could
become wedged into or under the vehicle.
For safety reasons, the vehicle can only be
lowered with all doors and the tailgate closed.
Lowering is interrupted if a door or the tailgate
Driving systems183Driving and parkingBA 251 USA, CA Edition A 2011; 1; 3, en-USd2sboikeVersion: 3.0.3.52010-04-16T14:31:55+02:00 - Seite 183Z

is opened and will continue after the door is
closed again.
! When driving in very poor road conditions,
select a high vehicle level in good time.
Make sure that there is always sufficient
ground clearance to prevent damage to the
vehicle.
! Remove the key from the ignition lock
before raising the vehicle completely, e.g.
with a vehicle lift.
Basic settings
Select raised level for very poor road
conditions ( Y page 184) or highway level for
normal road conditions ( Y page 185).
The vehicle is automatically lowered to high-
speed level when you:
R drive faster than 70 mph (112 km/h)
R drive at speeds between 60 mph
(96 km/h) and 70 mph (112 km/h) for
approximately 20 seconds.
The individual vehicle levels differ from
highway level as follows:
R +1.97 in (+ 50 mm) in raised level
R +/–0 in (+/–0 mm) in highway level
R –0.78 in (–20 mm) in high-speed level
i The high-speed level is not available if you
are towing a trailer. Observe the notes on
driving with a trailer ( Y page 193).
i Observe speed limits. Drive carefully and
at an appropriate speed.
Raised level
Only select raised level if this is appropriate
for the road conditions. Otherwise, fuel
consumption may increase and handling may
be affected.
If you select raised level at a speed above
40 mph (64 km/h), the Level Selection
Not Permitted message appears in the
multifunction display.XStart the engine.
Indicator lamp ; is not lit:
XPress button :.
Indicator lamp ; flashes. The vehicle rises
to raised level.
While the adjustment is taking place, a
message appears in the multifunction
display, e.g.:
If you press the V, U , * or &
button on the multifunction steering wheel,
the message will disappear.
Once the vehicle has reached raised level,
indicator lamp ; remains lit. A message
appears in the multifunction display for
approximately five seconds, e.g.:
The vehicle level is automatically set to
highway level if you are driving faster than
25 mph (40 km/h).
184Driving systemsDriving and parking
BA 251 USA, CA Edition A 2011; 1; 3, en-USd2sboikeVersion: 3.0.3.52010-04-16T14:31:55+02:00 - Seite 184

Highway level
! Make sure that there is enough ground
clearance when the vehicle is being
lowered. It could otherwise hit the ground,
damaging the underbody.XMake sure that the doors are closed.XStart the engine.
If indicator lamp ; is lit:
XPress button :.
Indicator lamp ; flashes. The vehicle is
lowered to highway level.
While the adjustment is taking place, a
message appears in the multifunction
display, e.g.:
If you press the V, U , * or &
button on the multifunction steering wheel,
the message will disappear.
Once highway level has been reached,
indicator lamp ; goes out. A message
appears in the multifunction display for
approximately five seconds, e.g.:
The vehicle level is automatically raised from
high-speed level to highway level if the speed
drops below 40 mph (64 km/h). The vehicle
level is automatically set to highway level if
you are driving faster than 25 mph
(40 km/h).
4MATIC (permanent four-wheel drive)
4MATIC ensures that all four wheels are
permanently driven. Together with ESP ®
and
4ETS , it improves the traction of your vehicle
whenever a drive wheel spins due to
insufficient grip.
GWarning!
If a drive wheel is spinning due to insufficient
traction:
R While driving off, apply as little throttle as
possible.
R While driving, ease up on the accelerator
pedal.
R Adapt your speed and driving style to the
prevailing road conditions.
Failure to observe these guidelines could
cause the vehicle to skid.
The 4MATIC cannot prevent accidents
resulting from excessive speed.
! Never tow the vehicle with one axle
raised. This may damage the transfer case.
Damage of this sort is not covered by the
Mercedes-Benz Limited Warranty. All
wheels must remain either on the ground
or be fully raised. Observe the instructions
for towing the vehicle with all wheels in full
contact with the ground.
i In wintry driving conditions, the maximum
effect of 4MATIC can only be achieved if
Driving systems185Driving and parkingBA 251 USA, CA Edition A 2011; 1; 3, en-USd2sboikeVersion: 3.0.3.52010-04-16T14:31:55+02:00 - Seite 185Z

Top view
Front sensors
CenterApprox. 40 in (100 cm)CornersApprox. 24 in (60 cm)
Rear sensors
CenterApprox. 48 in (120 cm)CornersApprox. 32 in (80 cm)
! When parking, pay particular attention to
objects above or below the sensors, such
as flower pots or trailer drawbars.
PARKTRONIC does not detect such objects
when they are in the immediate vicinity of
the vehicle. You could damage the vehicle
or the objects.
Ultrasonic sources such as an automatic
car wash, a truck's compressed-air brakes
or a pneumatic drill could cause
PARKTRONIC to malfunction.
Minimum distance
CenterApprox. 8 in (20 cm)CornersApprox. 6 in (15 cm)
If there is an obstacle within this range, all
warning displays light up and a warning tone
sounds. If the distance falls below the
minimum, the distance may no longer be
shown.
Warning displays
The warning displays show the distance
between the sensors and the obstacle. The
warning display for the front area is located
on the dashboard above the center air vents.
The warning display for the rear area is in the
roof lamp in the rear compartment.
Warning display for the front area
:Segments on the left-hand side of the
vehicle;Segments on the right-hand side of the
vehicle=Segments showing operational readiness
The warning display for each side of the
vehicle is divided into five yellow and two red
segments. PARKTRONIC is operational if
yellow segments showing operational
readiness = light up.
The selected transmission position
determines which warning display is active
when the engine is running.
Transmission
positionWarning displayDFront area activatedR or NRear and front areas
activatedPNo areas activated
One or more segments light up as the vehicle
approaches an obstacle, depending on the
vehicle's distance from the obstacle.
Driving systems187Driving and parkingBA 251 USA, CA Edition A 2011; 1; 3, en-USd2sboikeVersion: 3.0.3.52010-04-16T14:31:55+02:00 - Seite 187Z