engine overheat MERCEDES-BENZ GL-Class 2014 X166 Owner's Manual

G
WARNING
Unsuitable footwear can hinder correct usage
of the pedals, e.g.:
R shoes with thick soles
R shoes with high heels
R slippers
There is a risk of an accident.
Wear suitable footwear to ensure correct
usage of the pedals. G
WARNING
If you switch off the ignition while driving,
safety-relevant functions are only available
with limitations, or not at all. This could affect,
for example, the power steering and the brake
boosting effect. You will require considerably
more effort to steer and brake. There is a risk
of an accident.
Do not switch off the ignition while driving. G
WARNING
If the parking brake has not been fully
released when driving, the parking brake can:
R overheat and cause a fire
R lose its hold function.
There is a risk of fire and an accident. Release
the parking brake fully before driving off.
! Warm up the engine quickly. Do not use
the engine's full performance until it has
reached operating temperature.
Only shift the automatic transmission to
the desired drive position when the vehicle
is stationary.
Where possible, avoid spinning the drive
wheels when pulling away on slippery
roads. You could otherwise damage the
drive train.
! AMG vehicles: at low engine oil
temperatures below 68 ‡ (+20 †), the
maximum engine speed is restricted in
order to protect the engine. To protect the
engine and maintain smooth engine operation, avoid driving at full throttle when
the engine is cold. SmartKey positions
SmartKey g
To remove the SmartKey
1 Power supply for some consumers, such
as the windshield wipers
2 Ignition (power supply for all consumers)
and drive position
3 To start the engine
i The SmartKey can be turned in the
ignition lock even if it is not the correct
SmartKey for the vehicle. The ignition is not
switched on. The engine cannot be started.
KEYLESS-GO General notes
R
Do not keep the KEYLESS-GO key:
-with electronic devices, e.g. a mobile
phone or another SmartKey
- with metallic objects, e.g. coins or metal
foil
- inside metallic objects, e.g. a metal case
This can impair the functionality of the
KEYLESS-GO key.
Do not keep the KEYLESS-GO key in the
temperature-controlled cup holder
(Y page 349). Otherwise, the KEYLESS-GO
key will not be recognized.
Vehicles with KEYLESS-GO are equipped with
a SmartKey featuring an integrated KEYLESS- Driving
167Driving and parking Z

If you or others come into contact with fuel,
observe the following:
R Wash away fuel from skin immediately
using soap and water.
R If fuel comes into contact with your eyes,
immediately rinse them thoroughly with
clean water. Seek medical assistance
without delay.
R If fuel is swallowed, seek medical
assistance without delay. Do not induce
vomiting.
R Immediately change out of clothing which
has come into contact with fuel. G
WARNING
Electrostatic buildup can create sparks and
ignite fuel vapors. There is a risk of fire and
explosion.
Always touch the vehicle body before opening
the fuel filler flap or touching the fuel pump
nozzle. Any existing electrostatic buildup is
thereby discharged. G
WARNING
Vehicles with a diesel engine:
If you mix diesel fuel with gasoline, the flash
point is lower than that of pure diesel fuel.
When the engine is running, exhaust system
components could overheat without being
noticed. There is a risk of fire.
Never refuel with gasoline. Never mix gasoline
with diesel fuel.
! Do not use gasoline to refuel vehicles with
a diesel engine. Do not use diesel to refuel
vehicles with a gasoline engine. Do not
switch on the ignition if you accidentally
refuel with the wrong fuel. Otherwise, the
fuel will enter the fuel system. Even small
amounts of the wrong fuel could result in
damage to the fuel system and the engine.
The repair costs are high. Notify a qualified
specialist workshop and have the fuel tank
and fuel lines drained completely. !
Do not use diesel to refuel vehicles with a
gasoline engine. Do not switch on the
ignition if you accidentally refuel with the
wrong fuel. Otherwise, the fuel will enter
the fuel system. Even small amounts of the
wrong fuel could result in damage to the
fuel system and the engine. Notify a
qualified specialist workshop and have the
fuel tank and fuel lines drained completely.
! Overfilling the fuel tank could damage the
fuel system.
! Take care not to spill any fuel on painted
surfaces. You could otherwise damage the
paintwork.
! 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.
Do not get into the vehicle again during the
refueling process. Otherwise, electrostatic
charge could build up again.
If you overfill the fuel tank, fuel could spray
out when the fuel pump nozzle is removed.
For further information on fuel and fuel quality
(Y page 446).
You will find further information on fuel and
fuel quality in the printed Operator's Manual
under "Technical data". Refueling
General information Pay attention to the important safety notes
(Y
page 182).
The fuel filler flap is unlocked or locked
automatically when you open or close the
vehicle with the SmartKey or with KEYLESS-
GO.
The position of the fuel filler cap is displayed
8 in the instrument cluster. The arrow
next to the filling pump indicates the side of
the vehicle. Refueling
183Driving and parking Z

in the ECO display does not indicate a fixed
consumption.
Apart from driving style, consumption is
dependent on many factors such as, e.g.:
R Load
R Tire pressure
R Cold start
R Choice of route
R Electrical consumers switched on
These factors are not included in the ECO
display.
The evaluation of your driving style is carried
out using the following three categories:
R Acceleration
Acceleration (evaluation of all
acceleration processes):
- The bar fills up: moderate acceleration,
especially at higher speeds
- The bar empties: sporty acceleration
R Constant Constant (assessment of driving behavior
at all times):
- The bar fills up: constant speed and
avoidance of unnecessary acceleration
and deceleration
- The bar empties: fluctuations in speed
R Coasting
Coasting (assessment of all deceleration
processes):
- The bar fills up: anticipatory driving,
keeping your distance and early release
of the accelerator. The vehicle can coast
without use of the brakes.
- The bar empties: frequent braking
i An economical driving style specially
requires driving at moderate engine
speeds.
To achieve a higher value in the categories
Acceleration
Acceleration andConstant Constant , observe the
gearshift recommendations.
i On long journeys at a constant speed, e.g.
on the highway, only the bar for Constant
Constant
will change.
i The ECO display summarizes the driving
characteristics from the start of the journey
to its completion. For this reason, the bars change dynamically at the beginning of the
journey. On longer journeys, there are
fewer changes. For more dynamic changes,
carry out a manual reset.
For further information on the ECO display,
see (Y page 276). Braking
Important safety notes G
WARNING
If you shift down on a slippery road surface in
an attempt to increase the engine's braking
effect, the drive wheels could lose their grip.
There is an increased danger of skidding and
accidents.
Do not shift down for additional engine
braking on a slippery road surface.
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.
Do not depress the brake pedal continuously
while the vehicle is in motion, e.g. causing the
brakes to rub by constantly applying light
pressure to the pedal. This results in
excessive and premature wear to the brake
pads.
Heavy and light loads G
WARNING
If you rest your foot on the brake pedal while
driving, the braking system can overheat. This Driving tips
193Driving and parking
Z

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 Shift to a lower gear using the left-hand
paddle shifter before tackling steep
downhill gradients.
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. This causes them to dig into
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
General notes Cruise control maintains a constant road
speed for you. It brakes automatically in order
to avoid exceeding the set speed. You must
select a lower gear in good time on long and
steep downhill gradients, especially if the
vehicle is laden or towing a trailer. By doing
so, you will make use of the braking effect of
the engine. This 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). i
Cruise control should not be activated
when driving off-road.
Important safety notes If you fail to adapt your driving style, cruise
control can neither reduce the risk of an
accident nor override the laws of physics.
Cruise control cannot take into account the
road, traffic and weather conditions. Cruise
control is only an aid. You are responsible for
the distance to the vehicle in front, for vehicle
speed, for braking in good time and for
staying in your lane.
Do not use cruise control:
R in road and traffic conditions which do not
allow you to maintain a constant speed e.g.
in heavy traffic or on winding roads
R on slippery road surfaces. Braking or
accelerating could cause the drive wheels
to lose traction and the vehicle could then
skid
R when there is poor visibility, e.g. due to fog,
heavy rain or snow
If there is a change of drivers, advise the new
driver of the speed stored.
Cruise control lever :
To activate or increase speed
; To activate or reduce speed
= To deactivate cruise control
? To activate at the current speed/last
stored speed Driving syste
ms
201Driving an d parking Z

You must select a lower gear in good time on
long and steep downhill gradients, especially
if the vehicle is laden or towing a trailer. By
doing so, you will make use of the braking
effect of the engine. This relieves the load on
the brake system and prevents the brakes
from overheating and wearing too quickly.
If DISTRONIC PLUS detects a slower-moving
vehicle in front, your vehicle is braked in order
to maintain the preset distance to the vehicle
in front.
If DISTRONIC PLUS detects that there is a risk
of a collision, you will be warned visually and
acoustically. DISTRONIC PLUS cannot
prevent a collision without your intervention.
An intermittent warning tone will then sound
and the distance warning lamp will light up in
the instrument cluster. Brake immediately in
order to increase the distance to the vehicle
in front or take evasive action provided it is
safe to do so.
For DISTRONIC PLUS to assist you, the radar
sensor system must be operational.
If there is no vehicle in front, DISTRONIC
PLUS operates in the same way as cruise
control in the speed range between 20 mph
(Canada: 30 km/h) and 120 mph (Canada:
200 km/h). If a vehicle is driving in front of
you, it operates in the speed range between
0 mph (0 km/h) and 120 mph (Canada:
200 km/h).
Do not use DISTRONIC PLUS while driving on
roads with steep gradients.
As DISTRONIC PLUS transmits radar waves,
it can resemble the radar detectors of the
responsible authorities. You can refer to the
relevant chapter in the Operator's Manual if
questions are asked about this.
i USA only:
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 not permitted by the FCC. Do not tamper with, alter, or use in
any non-approved way.
Any unauthorized modification to this
device could void the user’s authority to
operate the equipment.
i Canada only: This device complies with
RSS-210 of Industry Canada. Operation is
subject to the following two conditions:
1. This device may not cause harmful
interference, and
2. this device must accept any interference
received, including interference that may
cause undesired operation of the device.
Removal, tampering, or altering of the
device will void any warranties, and is not
permitted. Do not tamper with, alter, or use
in any non-approved way.
Any unauthorized modification to this
device could void the user's authority to
operate the equipment.
Important safety notes G
WARNING
DISTRONIC PLUS does not react to:
R people or animals
R stationary obstacles on the road, e.g.
stopped or parked vehicles
R oncoming and crossing traffic
As a result, DISTRONIC PLUS may neither give
warnings nor intervene in such situations.
There is a risk of an accident.
Always pay careful attention to the traffic
situation and be ready to brake. G
WARNING
DISTRONIC PLUS cannot always clearly
identify other road users and complex traffic
situations.
In such cases, DISTRONIC PLUS may:
R give an unnecessary warning and then
brake the vehicle
R neither give a warning nor intervene
R accelerate unexpectedly 204
Driving systemsDriving and parking

the brake system and prevents the brakes
from overheating and wearing too quickly. If
you need additional braking, depress the
brake pedal repeatedly rather than
continuously.
Driving tips If the trailer swings from side to side:
X Do not accelerate.
X Do not counter-steer.
X Brake if necessary.
R Maintain a greater distance from the
vehicle in front than when driving without a
trailer.
R Avoid braking abruptly. If possible, brake
gently at first to allow the trailer to run on.
Then, increase the braking force rapidly.
R The values given for gradient-climbing
capabilities from a standstill refer to sea
level. When driving in mountainous areas,
note that the power output of the engine
and, consequently, the vehicle's gradient-
climbing capability, decreases with
increasing altitude. Installing the ball coupling
G
WARNING
If the ball coupling is not correctly installed
and secured, it can come loose during the
journey and endanger other road users. There
is a risk of an accident and injury.
Always install and secure the ball coupling as
described. Before every journey, ensure that
the ball coupling is secured with the bolt and
the corresponding spring cotter. G
WARNING
If the ball coupling is not installed correctly or
not secured with the bolt provided and the
corresponding spring cotter, the trailer may
come loose. There is a risk of an accident.
Always install and secure the ball coupling as
described. Before every journey, ensure that the ball coupling is secured with the bolt and
the corresponding spring cotter.
G
WARNING
If the ball coupling is not installed and secured
correctly the trailer may come loose. There is
a risk of an accident.
Install and secure the ball coupling as
described in the ball coupling installation
instructions. Make sure that the ball coupling
is installed and secured correctly before every
journey. Cover cap
X
Pull protective cap :in the direction of the
arrow, out of the ball coupling recess.
X Place protective cap :in the ball coupling
recess. Towing a trailer
265Driving and parking Z

R
Secure any objects on the trailer to prevent
the cargo from slipping when the vehicle is
in motion.
R If you couple up a trailer, regularly check
that the cargo is securely fastened and
make sure that the trailer lamps and (if
applicable) the trailer brakes are
functioning correctly.
R Bear in mind that the handling will be less
stable when towing a trailer than when
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 repeatedly
shifts between gears on uphill or downhill
gradients, shift to a lower gear using the
left-hand steering wheel paddle shifter.
A lower gear and lower speed reduce the
risk of engine failure.
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 trailer
G
WARNING
If you uncouple a trailer with the overrun
brake engaged, you could trap your hand
between the vehicle and the trailer drawbar.
There is a risk of injury.
Do not uncouple a trailer if the overrun brake
is engaged. G
WARNING
Vehicles with level control:
The vehicle is lowered as soon as you
disconnect the trailer cable. This could result
in your limbs or those of other people that are
between the vehicle body and tires or
underneath the vehicle being trapped. There
is a risk of injury.
Make sure that nobody is in the immediate
vicinity of the wheel housings or under the
vehicle when you disconnect the trailer cable.
! Do not disconnect a trailer with an
engaged overrun brake. Otherwise, your
vehicle could be damaged by the
rebounding of the overrun brake.
X Make sure that the automatic transmission
is set to position P.
X Apply the vehicle's electric parking brake.
X Start the engine.
X Close all doors and the tailgate.
X Apply the trailer's parking brake.
X Detach the trailer cable and decouple the
trailer.
X Switch off the engine. 268
Towing a trailerDriving and parking

Useful information
i This Operator's Manual describes all
models and all standard and optional
equipment of your vehicle available at the
time of publication of the Operator's
Manual. Country-specific differences are
possible. Please note that your vehicle may
not be equipped with all features
described. This also applies to safety-
related systems and functions.
i Read the information on qualified
specialist workshops: (Y page 28).Important safety notes
G
WARNING
If you operate information systems and
communication equipment integrated in the
vehicle while driving, you will be distracted
from traffic conditions. You could also lose
control of the vehicle. There is a risk of an
accident.
Only operate the equipment when the traffic
situation permits. If you are not sure that this
is possible, park the vehicle paying attention
to traffic conditions and operate the
equipment when the vehicle is stationary. G
WARNING
If the instrument cluster has failed or
malfunctioned, you may not recognize
function restrictions in systems relevant to
safety. The operating safety of your vehicle
may be impaired. There is a risk of an
accident.
Drive on carefully. Have the vehicle checked
at a qualified specialist workshop
immediately.
You must observe the legal requirements for
the country in which you are currently driving
when operating the on-board computer.
The on-board computer only shows messages
or warnings from certain systems in the multifunction display. You should therefore
make sure your vehicle is operating safely at
all times. Otherwise, a vehicle that is not
operating safely may cause an accident.
For an overview, see the instrument panel
illustration (Y
page 33). Displays and operation
Instrument cluster lighting
The lighting in the instrument cluster, in the
displays and the controls in the vehicle
interior can be adjusted using the brightness
control knob.
The brightness control knob is located on the
bottom left of the instrument cluster
(Y page 33).
X Turn the brightness control knob clockwise
or counter-clockwise.
If the light switch is set to Ã,Tor
L, the brightness is dependent upon
the brightness of the ambient light.
i The light sensor in the instrument cluster
automatically controls the brightness of
the multifunction display.
In daylight, the displays in the instrument
cluster are not illuminated. Coolant temperature display
G
WARNING
Opening the hood when the engine is
overheated or when there is a fire in the
engine compartment could expose you to hot
gases or other service products. There is a
risk of injury.
Let an overheated engine cool down before
opening the hood. If there is a fire in the
engine compartment, keep the hood closed
and contact the fire department.
! A display message is shown if the coolant
temperature is too high. 272
Displays and operationOn-board computer and displays

Display messages Possible causes/consequences and
M
MSolutions ?
Coolant Too Hot Coolant Too Hot
Stop Vehicle Turn Stop Vehicle Turn
Engine Off Engine Off The coolant is too hot.
A warning tone also sounds.
G WARNING
Do not drive when your engine is overheated. This can cause some
fluids which may have leaked into the engine compartment to
catch fire.
Steam from the overheated engine can also cause serious burns
which can occur just by opening the hood.
There is a risk of injury.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Secure the vehicle against rolling away ( Ypage 188).
X Wait until the engine has cooled down.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.
X Do not start the engine again until the display message goes out
and the coolant temperature is below 248 ‡ (120 †).
Otherwise, the engine could be damaged.
X Pay attention to the coolant temperature display.
X If the temperature increases again, visit a qualified specialist
workshop immediately.
Under normal operating conditions and with the specified coolant
level, the coolant temperature may rise to 248 ‡ (120 †). # The battery is not being charged.
A warning tone also sounds.
Possible causes are:
R
a defective alternator
R a torn poly-V-belt
R a malfunction in the electronics
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Open the hood.
X Check whether the poly-V-belt is torn.
If the poly-V-belt is torn:
! Do not continue driving. The engine could otherwise overheat.
X Consult a qualified specialist workshop.
If the poly-V-belt is not damaged:
X Visit a qualified specialist workshop. Display
messages
307On-board computer and displays Z

Problem Possible causes/consequences and
M
MSolutions ?
The red coolant
warning lamp comes on
while the engine is
running.
The coolant level is too low.
!
Avoid making long journeys with too little coolant in the engine
cooling system. The engine will otherwise be damaged.
If the coolant level is correct, the airflow to the engine radiator
may be blocked or the electric engine radiator fan may be
malfunctioning.
The coolant is too hot and the engine is no longer being cooled
sufficiently.
X Observe the additional display messages in the multifunction
display.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 188).
X Leave the vehicle and keep a safe distance from the vehicle until
the engine has cooled down.
X Check the coolant level and add coolant, observing the warning
notes (Y page 373).
X If you need to add coolant more often than usual, have the
engine coolant system checked.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.
X Do not start the engine again until the coolant temperature is
below 248 ‡(120 †). Otherwise, the engine could be damaged.
X Drive to the nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-and-go traffic. ?
The red coolant
warning lamp comes on
while the engine is
running. A warning tone
also sounds.
The coolant temperature has exceeded 248 ‡ (120 †). The
airflow to the engine radiator may be blocked or the coolant level
may be too low.
G WARNING
The engine is not being cooled sufficiently and may be damaged.
Do not drive when your engine is overheated. This can cause some
fluids which may have leaked into the engine compartment to
catch fire.
Steam from the overheated engine can also cause serious burns
which can occur just by opening the hood.
There is a risk of injury. Warning and indicator lamps in the instrument cluster
335On-board computer and displays Z