2012 MERCEDES-BENZ GL-Class engine overheat

Driving tips
Kickdown
Use kickdown for maximum acceleration.
XVehicles for USA: fully depress the
accelerator pedal.
The transmission shifts to a lower gear
depending on the engine speed.XVehicles for Canada: depress the
accelerator pedal beyond the pressure
point.
The transmission shifts to a lower gear
depending on the engine speed.
Rocking the vehicle free
Rocking the vehicle free by shifting back and
forth between transmission positions D and
R can help to free a vehicle that has become
stuck in mud or snow. The engine
management system of the vehicle limits
shifting back and forth between transmission
positions D and R to a maximum speed of
5 mph (9 km/h). To shift back and forth
between transmission positions D and R,
move the selector lever up and down beyond
the pressure point.
Working on the vehicle
GWARNING
When working on the vehicle, engage the
parking brake and shift the automatic
transmission into park position P. Otherwise
the vehicle could roll away which could result
in an accident and/or serious personal injury.
Trailer towing
XWhen towing a trailer and driving downhill,
shift to the lower gear if the automatic
transmission constantly shifts between
two gears.XEngaging a lower gear and reducing the
speed reduces the risk of the engine
overheating.Steering wheel paddle shifters:Left-hand steering wheel paddle shifter;Right-hand steering wheel paddle shifter
You can restrict or derestrict the shift range
by using the steering wheel paddle shifters.
Shift ranges
Introduction
When the automatic transmission is in
position D, it is possible to restrict or
derestrict the shift range ( Y page 157).
The shift range selected is shown in the
multifunction display. The automatic
transmission shifts only as far as the selected
gear.
Driving situations=You can use the engine's braking
effect.5To use the braking effect of the
engine on downhill gradients and
for driving:
R on steep mountain roads
R in mountainous terrain
R in arduous conditions4To use the braking effect of the
engine on extremely steep downhill
gradients and on long downhill
stretchesAutomatic transmission157Driving and parkingZ

to spray back out when removing the fuel
pump nozzle, which could cause personal
injury.GWARNING
Do not fill diesel tanks with gasoline. Do not
mix diesel fuel with gasoline. Otherwise the
fuel system and engine could be damaged. In
addition, the vehicle could catch fire.
! Do not use gasoline to refuel vehicles with
a diesel engine. Do not use diesel to refuel
vehicles with a gasoline engine. Even a
small quantity of the wrong fuel will
damage the fuel system and engine.
! Do not switch on the ignition if you
accidentally refuel with the wrong fuel.
Otherwise, the fuel will enter the fuel lines.
Notify a qualified specialist workshop and
have the fuel tank and fuel lines drained
completely.
Gasoline
Fuel grade
! You should only refuel with unleaded
premium-grade gasoline as this avoids
damaging the catalytic converter.
If engine running problems are apparent,
have the cause checked immediately and
repaired. Excess unburned fuel can
otherwise enter the catalytic converter,
leading to overheating and possibly
causing a fire.
! Use a filter when refueling from a fuel can.
Otherwise, the fuel lines and/or injection
system could be blocked by particles from
the fuel can.
i Only refuel with premium-grade unleaded
gasoline with a specified minimum octane
number of 91 (average value of 96 RON/
86 MON).
Usually, you will find information about the
fuel grade on the pump. If you cannot find
the label on the gasoline pump, ask the gas
station staff.
You can find more information under “Fuel”
( Y page 372), or by contacting an
authorized Mercedes-Benz Service Center
or visiting http://www.mbusa.com (USA
only).
Diesel
Fuel grade
! Only refuel with ULTRA-LOW SULFUR
DIESEL FUEL (ULSD, 15 ppm SULFUR
MAXIMUM). Using other diesel fuels could
result in increased wear and damage to the
engine and/or exhaust system.
Never refuel with marine diesel or heating
oil.
Do not mix these fuels with diesel fuels and
do not use any special additives, as this
may result in damage.
! Use a filter when adding fuel from a fuel
can. Otherwise, the fuel lines and/or the
fuel injection system could be blocked by
particles from the fuel can.
i Usually, you will find information about
the fuel grade on the pump. If you cannot
find the label on the gasoline pump, ask the
gas station staff.
You can find more information under “Fuel”
( Y page 372), or by contacting an
authorized Mercedes-Benz Service Center
or visiting http://www.mbusa.com (USA
only).
Low outside temperatures
! Do not use gasoline to refuel vehicles with
a diesel engine. Never mix diesel with
gasoline or kerosene, as this may result in
damage to the engine or fuel system.
Diesel fuel with improved cold flow properties
is available during the winter months. Further
information on fuel properties can be
160RefuelingDriving and parking

Exhaust checkGWARNING
Inhalation of exhaust gas is hazardous to your
health. All exhaust gas contains carbon
monoxide (CO), and inhaling it can cause
unconsciousness and possible death.
Do not run the engine in confined areas (such
as a garage) which are not properly ventilated.
If you think that exhaust gas fumes are
entering the vehicle while driving, have the
cause determined and corrected
immediately. If you must drive under these
conditions, drive only with at least one
window fully open at all times.
Certain engine systems are designed to keep
the level of poisonous components in exhaust
fumes within legal limits.
These systems only work at peak efficiency
when they are maintained exactly in
accordance with the manufacturer's
specifications. For this reason, all work on the
engine must be carried out only by qualified
and authorized Mercedes-Benz technicians.
The engine settings must not be changed in
any circumstances. Furthermore, all specific
service work must be carried out at regular
intervals and in accordance with the
Mercedes-Benz service requirements. Details
can be found in the Service Booklet.
Engine oil
! Vehicles with a diesel particle filter:
If the vehicle is mostly driven for short
distances, it is possible that malfunctions
may occur during the automatic cleaning of
the diesel particle filter. This can lead to
engine damage. Therefore, if you frequently
drive short distances, make sure to drive
on highways or inter-urban roads for 20
minutes at least every 310 miles (500 km).
Brakes
Important safety notesGWARNING
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 control loss.
Do not engage the transfer case in position
LOW when driving on ice or packed snow. At
speeds below 18 mph (30 km/h) vehicle
steering is adversely affected by the Off-road
ABS.
GWARNING
Make sure that you do not endanger other
road users when you apply the brakes.
Downhill gradients
! On long and steep gradients, you must
reduce the load on the brakes by shifting
early to a lower gear. This allows you to take
advantage of the engine braking effect and
helps avoid overheating and excessive
wear of the brakes.
When you take advantage of the engine
braking effect, a drive wheel may not turn
for some time, e.g. on a slippery road
surface. This could cause damage to the
drive train. This type of damage is not
covered by the Mercedes-Benz warranty.
Heavy and light loads
GWARNING
Depressing the brake pedal constantly results
in excessive and premature wear to the brake
pads.
It may also cause the brakes to overheat,
seriously impairing their effectiveness. It may
then not be possible to stop the vehicle in
sufficient time to avoid an accident.
If the brakes have been subjected to a heavy
load, do not stop the vehicle immediately, but
Driving tips169Driving and parkingZ

GWARNING
Never turn the vehicle around on steep inclines. The vehicle might roll over. If the vehicle cannot
complete the attempted climb, back it down in reverse gear.
i Hill start assist will aid you when pulling away on a hill.
For more information, see "Hill start assist" ( Y page 151).
Maximum gradient-climbing capability
For good road surface conditions, the
maximum gradient-climbing capability is
100%, which corresponds to an approach/
departure angle of 45°. Note that the
vehicle's gradient-climbing capability
depends on the off-road conditions.
Accelerate carefully and make sure that the
wheels do not spin when driving on steep
terrain.
i If the load on the front axle is reduced
when pulling away on a steep uphill slope,
the front wheels have a tendency to spin.
4ETS recognizes this and brakes the
wheels accordingly. The rear wheel torque
is increased, making it easier to drive off.
i Vehicles with the Enhanced Off-Road
Package have a differential lock for the
transfer case and a differential lock for the
rear axle to improve vehicle traction.
Brow of hill
When driving up an uphill gradient, slightly
reduce pressure on the accelerator
immediately before reaching the brow of the
hill. Use the vehicle's own impetus to drive
over the top of the hill.
This style of driving prevents:
R the vehicle from lifting off the ground on the
brow of a hill
R loss of traction
R the vehicle from traveling too quickly down
the other side
Driving downhill
R Drive slowly.
R Do not drive at an angle down steep
inclines. Steer into the line of fall and drive
with the front wheels aligned straight.
Otherwise, the vehicle could slip sideways,
tip and rollover.
R Before tackling steep downhill gradients,
select shift range 1.
R Activate DSR. If this is not sufficient, brake
gently. When doing so, make sure that the
vehicle is facing in the direction of the line
of fall.
R Check that the brakes are working normally
after a long downhill stretch.
i The special off-road ABS setting enables
a precise, brief and repeated locking of the
front wheels, causing them to dig into the
loose earth. Be aware that the front wheels
easily skid across the ground surface if
completely braked and therefore lose their
ability to steer.
Driving systems
Cruise control
Important safety notes
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.
Driving systems179Driving and parkingZ

DISTRONIC
Important safety notes
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.
If there is no vehicle driving in front of you,
DISTRONIC functions like cruise control at a
speed range between 20 mph (30 km/h) and
120 mph (200 km/h). If a vehicle is driving in
front of you, it functions at a speed range
between 0 mph (0 km/h) and 120 mph
(200 km/h).
Do not use DISTRONIC while driving on roads
with steep gradients.GWARNING
DISTRONIC distance control is not a
substitute for the driver's active involvement.
It does not react to pedestrians or stationary
objects and cannot detect or predict the
road's course and the movements of the
vehicles in front.
DISTRONIC can only brake using 40% of the
vehicle's maximum possible braking force.
The driver must always pay attention to road,
weather and traffic conditions. He must steer,
brake and drive the vehicle so that he
maintains control over it.
High-frequency sources such as toll stations,
velocity measurement systems, etc. may
cause DISTRONIC to malfunction.
GWARNING
The Distronic cannot take road and traffic
conditions into account. Only use the
Distronic if the road, weather and traffic
182Driving systemsDriving and parking

driving without one. Avoid sudden steering
movements.
R The vehicle/trailer combination is heavier,
accelerates more slowly, has a decreased
gradient climbing capability and a longer
braking distance.
It is more susceptible to side winds and
requires more careful steering.
R If possible, avoid abrupt braking. Depress
the brake pedal moderately at first, so that
the trailer can activate its own brakes. Then
increase the pressure on the brake pedal.
R If the automatic transmission continues to
shift back and forth between two gears
when driving up or downhill, restrict the
shift range. Select shift range 4, 3, 2, or 1.
A lower gear and lower speed reduce the
risk of engine failure.
R On long and steep gradients that are
difficult to drive down in shift range 1,
switch to the off-road drive program or
engage the LOW RANGE off-road gear.
R When driving downhill, shift to a lower gear
to utilize the engine's braking effect.
Avoid continuous brake application as this
may overheat the vehicle brakes and, if
installed, the trailer brakes.
R If the coolant temperature increases
dramatically while the air-conditioning
system is switched on, switch off the air-
conditioning system.
Coolant heat can additionally be dissipated
by opening the windows and by setting the
blower fan and the interior temperature to
maximum.
R When overtaking, pay particular attention
to the extended length of your vehicle/
trailer combination.
Due to the length of your vehicle/trailer
combination, you will have to travel an
additional distance beyond the vehicle you
are overtaking before returning to the
previous lane.Decoupling a trailerGWARNING
While you are coupling or decoupling a trailer,
make sure nobody locks or unlocks the
vehicle and/or opens or closes doors or the
tailgate.
The vehicle's level could change and you
could endanger yourself and/or others as a
result.
Make sure that you do not operate the ADS
button or the vehicle level control system
when coupling/decoupling the trailer.
XMake sure that the automatic transmission
is set to position P.XApply the vehicle's parking brake.XStart the engine.XClose all doors and the tailgate.XApply the trailer's parking brake.GWARNING
As soon as you disconnect the electrical
connection between the trailer and the
vehicle, the vehicle will lower. To help avoid
personal injury, make sure no one is near the
wheel housing or underneath the vehicle
before the electrical connection is
disconnected.
When you decouple the trailer, the vehicle is
temporarily raised because the springs are
relieved of load. Be especially careful during
this process, as you could otherwise injure
yourself and/or others. Make sure that any
persons remaining in the vehicle do not press
the switches for vehicle level control or the
ADS.
XRemove the trailer cable and decouple the
trailer.XSwitch off the engine.212Trailer towingDriving and parking

FunctionETrip computer menu (Y page 229)FTelephone menu (Y page 230)Standard display menu
Standard displayXPress the V or U button on the
steering wheel to select the standard
display.
Standard display
:Trip odometer;Odometer
You can select the following functions in the
Standard display menu using the & or
* button:
R tire pressure loss warning system
( Y page 345) (Canada only)
R tire pressure monitor ( Y page 347) (USA
only)
R coolant temperature ( Y page 220)
R digital speedometer or outside
temperature ( Y page 220)
R ASSYST PLUS service interval display
( Y page 305)
XTo reset the trip odometer: press and
hold the . reset button in the instrument
cluster until the trip odometer is reset.
Displaying the coolant temperature
GWARNING
Driving when your engine is overheated can
cause some fluids which may have leaked into
the engine compartment to catch fire. You
could be seriously burned.
Steam from an overheated engine can cause
serious burns which can occur just by opening
the engine hood. Stay away from the engine
if you see or hear steam coming from it.
Stop the vehicle in a safe location away from
other traffic. Turn off the engine, get out of the
vehicle and do not stand near the vehicle until
the engine has cooled down.XPress the V or U button on the
steering wheel to select the standard
display.XPress the & or * button to select the
coolant temperature.
Under normal driving conditions, with the
correct anti-corrosion and antifreeze additive
concentration, the reading may rise to
248 ‡(120 †).
! If the coolant temperature exceeds
248 ‡(120 †) do not continue driving. The
engine will otherwise be damaged.
Displaying the digital speedometer or
outside temperature
If you have selected the digital speedometer
for the status bar ( Y page 224), the outside
temperature is displayed here.
220Menus and submenusOn-board computer and displays

Display messagesPossible causes/consequences and M Solutions?
Coolant Stop car,
switch engine offThe coolant is too hot.XPull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.XMake sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.XWait until the display message disappears before restarting the
engine. Otherwise, there is a risk of engine damage.XPay attention to the coolant temperature display.XIf the temperature increases again, visit a qualified specialist
workshop immediately.The poly-V-belt may have torn.XPull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.XOpen the hood.XCheck whether the poly-V-belt is torn.
If the poly-V-belt is torn:
! Do not continue driving. The engine could otherwise overheat.
XConsult a qualified specialist workshop.
If the poly-V-belt is OK:
XWait until the display message disappears before restarting the
engine. Otherwise, there is a risk of engine damage.XPay attention to the coolant temperature display.XVisit a qualified specialist workshop.GWARNING
Driving when your engine is overheated can cause some fluids which may have leaked into the
engine compartment to catch fire. You could be seriously burned.
Steam from an overheated engine can cause serious burns which can occur just by opening the
engine hood. Stay away from the engine if you see or hear steam coming from it.
Stop the vehicle in a safe location away from other traffic. Turn off the engine, get out of the
vehicle and do not stand near the vehicle until the engine has cooled down.
! If the coolant temperature exceeds 248 ‡(120 †) do not continue driving. The engine will
otherwise be damaged.
Display messages245On-board computer and displaysZ