engine overheat MERCEDES-BENZ G-CLASS SUV 2014 Owners Manual

Make sure that all objects in the vehicle are
stowed correctly, and that they cannot enter
the driver's footwell. Install the floormats
securely and as specified in order to ensure
sufficient clearance for the pedals. Do not use
loose floormats. 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. !
Avoid high engine speeds when the
engine is cold. The engine's service life
could otherwise be significantly shortened.
Do not use the engine's full performance
until it has reached operating temperature.
! 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. Key positions
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
As soon as the ignition is switched on, all the
indicator lamps in the instrument cluster light
up. If an indicator lamp does not go out after
starting the engine or lights up while driving,
see (Y page 159).
If the SmartKey is in position 0in the ignition
lock for an extended period of time, it can no
longer be turned in the ignition lock. The
steering is then locked. To unlock, remove the
SmartKey and reinsert it into the ignition lock.
The steering is locked when you remove the
SmartKey from the ignition lock. Driving
97Driving and parking Z

X
Clean the wheels, tires, wheel housings and
the vehicle underside with a water jet;
check for any foreign objects and damage.
X Check whether twigs or other parts of
plants have become trapped. These
increase the risk of fire and can damage
fuel pipes, brake hoses or the rubber
bellows of the axle joints and propeller
shafts.
X After the trip, examine without fail the
entire undercarriage, wheels, tires, brakes,
bodywork structure, steering, chassis and
exhaust system for damage.
X After driving for extended periods across
sand, mud, gravel, water or in similarly dirty
conditions, have the brake discs, wheels,
brake pads/linings and axle joints checked
and cleaned.
X If you notice strong vibrations after off-road
driving, check for foreign objects in the
wheels and drive train and, if necessary,
remove them.
Foreign objects can disturb the balance
and cause vibrations.
X Test the brakes. Driving systems
Cruise control
Important safety notes G
WARNING
The brake pedal moves when cruise control
brakes the vehicle. A foot in the area under
the brake pedal could become trapped. The
movement of the pedal, and therefore the
vehicle's ability to brake, may be restricted by
objects in the area under the brake. There is
a risk of an accident and injury.
Do not place your foot under the brake pedal.
Keep the area under the brake pedal free from
obstructions.
If you fail to adapt your driving style, cruise
control can neither reduce the risk of accident nor override the laws of physics.
Cruise control cannot take account of road,
weather and traffic conditions. Cruise control
is only an aid. You are responsible for the
distance to the vehicle in front, for vehicle
speed and for braking in good time. Adjust
your driving style to the traffic conditions.
Only engage cruise control when the current
road, weather and traffic conditions permit it
to be done safely. Drive carefully and
maintain a suitable distance to the vehicle in
front.
Do not use cruise control:
R
in traffic conditions that do not allow you
to drive at a constant speed, e.g. heavy
traffic, on winding roads or off-road
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
General notes Cruise control maintains a constant road
speed for you. On long and steep downhill
gradients, especially if the vehicle is laden,
you must select shift range
1,2or 3in 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).
i Cruise control should not be activated
during off-road driving. Driving systems
109Driving and parking Z

Deactivating cruise control
There are several ways to deactivate cruise
control:
X Briefly press the cruise control lever
forwards B.
or
X Brake.
or
X Briefly press the cruise control lever in the
direction of arrow A.
Variable SPEEDTRONIC is selected. LIM
indicator lamp ;in the cruise control lever
lights up.
Cruise control is automatically deactivated if:
R you apply the parking brake
R you are driving at less than 20 mph
(30 km/h)
R ESP ®
intervenes or you deactivate ESP ®
R you shift the transmission to position N
while driving
i The last speed stored is cleared when you
switch off the engine. SPEEDTRONIC
Important safety notes G
WARNING
If you rest your foot on the brake pedal while
driving, the braking system can overheat. This
increases the stopping distance and can even
cause the braking system to fail. There is a
risk of an accident.
Never use the brake pedal as a footrest. Never
depress the brake pedal and the accelerator
pedal at the same time.
! Depressing the brake pedal constantly
results in excessive and premature wear to
the brake pads.
If you fail to adapt your driving style,
SPEEDTRONIC can neither reduce the risk of
accident nor override the laws of physics. SPEEDTRONIC cannot take account of road,
weather and traffic conditions.
SPEEDTRONIC 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 lane. Only engage
SPEEDTRONIC when the current road,
weather and traffic conditions permit it to be
done safely. Drive carefully and maintain a
suitable distance to the vehicle in front.
General notes
SPEEDTRONIC brakes automatically so that
you do not exceed the set speed. On long and
steep downhill gradients, especially if the
vehicle is laden or towing a trailer, you must
select shift range
1,2or 3in 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
you need additional braking, depress the
brake pedal repeatedly rather than
continuously.
i The speed indicated in the speedometer
may differ slightly from the limit speed
stored.
Cruise control lever :
To store the current speed or a higher
speed
; LIM indicator lamp
= To call up the last speed stored
? To store the current speed or a lower
speed 112
Driving syste
msDriving and parking

road, weather and traffic conditions.
DISTRONIC PLUS 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 lane. Only engage
DISTRONIC PLUS when the current road,
weather and traffic conditions permit it to be
done safely, and adapt your driving style
accordingly. Drive carefully and maintain a
suitable distance to the vehicle in front.
If DISTRONIC PLUS detects a risk of collision
but cannot sufficiently decelerate the vehicle
in order to maintain the set distance, 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 from the vehicle in
front, or take evasive action, provided it is
safe to do so.
DISTRONIC PLUS may not detect narrow
vehicles driving in front, e.g. motorcycles, or
vehicles driving on a different line. Therefore,
always pay attention to traffic conditions
even when DISTRONIC PLUS is activated.
Otherwise, you may fail to recognize dangers
in time, cause an accident and injure yourself
and others.
In particular, the detection of obstacles can
be impaired if there is:
R the sensor is dirty or covered
R snow or heavy rain
R interference by other radar sources
R there is the possibility of strong radar
reflections, for example, in parking
garages.
If DISTRONIC PLUS is activated, the vehicle
brakes automatically in certain situations.
This can happen unexpectedly, especially
when towing or in a car wash. There is a risk
of an accident. In these or similar situations,
deactivate DISTRONIC PLUS.
If you want DISTRONIC PLUS to assist you,
the following activation conditions must be fulfilled (Y
page 116) and the radar sensor
system must be operational.
General notes DISTRONIC PLUS regulates the speed and
automatically helps you maintain the
distance to the vehicle detected in front.
DISTRONIC PLUS brakes automatically so
that the set speed is not exceeded.
On long and steep downhill gradients,
especially if the vehicle is laden or towing a
trailer, you must select shift range
1,2or 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 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 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) and120 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. Removal, tampering, or
altering of 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. Driving systems
115Driving and parking Z

Couple and uncouple the trailer carefully. If
you do not couple the trailer to the towing
vehicle correctly, the trailer could become
detached.
Make sure that the following values are not
exceeded:
R the permissible trailer drawbar noseweight
R the permissible trailer load
R the permissible rear axle load of the towing
vehicle
R the maximum permissible gross vehicle
weight of both the towing vehicle and the
trailer
When towing a trailer, your vehicle's handling
characteristics will be different in comparison
with when driving without a trailer.
The vehicle/trailer combination:
R is heavier
R is restricted in its acceleration and
gradient-climbing capability
R has an increased braking distance
R is affected more by strong crosswinds
R demands more sensitive steering
R has a larger turning circle
This could impair the handling
characteristics.
When towing a trailer, always adjust your
speed to the current road and weather
conditions. Do not exceed the maximum
permissible speed for your vehicle/trailer
combination.
Driving tips X
On long and steep downhill gradients,
select shift range 1,2or 3(Y page 101) in
good time.
i This also applies if you have activated
cruise control or SPEEDTRONIC.
X If necessary, shift the transfer case to LOW
RANGE(Y page 130).
This will use the braking effect of the
engine, so that less braking will be required
to maintain the speed. This relieves the load on 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.
The maximum permissible speed for vehicle/
trailer combinations depends on the type of
trailer. Before beginning the journey, check
the trailer's documents to see what the
maximum permissible speed is. Observe the
legally prescribed maximum speed in the
relevant country.
For certain Mercedes-Benz vehicles, the
maximum permissible rear axle load is
increased when towing a trailer. Refer to the
"Technical data" section to find out whether
this applies to your vehicle. If you utilize any
of the added maximum rear axle load when
towing a trailer, the vehicle/trailer
combination may not exceed a maximum
speed of 60 mph (100 km/h) for reasons
concerning the operating permit. This also
applies in countries in which the permissible
maximum speed for vehicle/trailer
combinations is above 60 mph (100 km/h).
When towing a trailer, your vehicle's handling
characteristics will be different in comparison
to when driving without a trailer and it will
consume more fuel.
On long and steep downhill gradients, you
must select shift range 1,2or 3in good time.
i This also applies if you have activated
cruise control or DISTRONIC PLUS.
This will use the braking effect of the engine,
so that less braking will be required to
maintain the speed. This relieves the load on
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. Towing a trailer
135Driving and parking Z

residence but also at any location to which
you are traveling. The police and local
authorities can provide reliable information.
Please observe the following when towing a
trailer:
R To acquaint yourself with driving with a
trailer and with the resulting changes to
handling, you should practice cornering,
stopping and backing up in a traffic-free
location.
R Before driving, check:
-Trailer tow hitch
- Safety switch for braked trailers
- Safety chains
- Electrical connections
- Lights
- Wheels
R Adjust the exterior mirrors to provide an
unobstructed view of the rear section of the
trailer.
R If the trailer features electronically
controlled brakes, pull away the vehicle/
trailer combination carefully, manually
brake using the brake controller, and check
the brakes for correct function.
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
the cargo for secure fastening 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 continues to
shift back and forth between two gears
when driving up or downhill, restrict the
shift range. Select shift range 4, 3, 2,or1.
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
! 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 parking brake.
X Start the engine. Towing a trailer
139Driving and parking Z

Engine
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 104).
X Leave the vehicle and keep a safe distance from the vehicle 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 poly-V-belt may have torn.
X
Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Check the poly-V-belt.
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 Wait until the display message disappears before restarting the
engine. Otherwise, the engine could be damaged.
X Pay attention to the coolant temperature display.
X Visit a qualified specialist workshop. 152
Display messagesOn-board computer and displays

Engine
Problem Possible causes/consequences and
M
MSolutions ?
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.
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 104).
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 203).
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 At coolant temperatures below 248 ‡ (120 †), drive to the
nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-start driving. Warning and indicator lamps in the instrument cluster
165On-board computer and displays Z

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 27).Engine compartment
Hood
Important safety notes G
WARNING
If the hood is unlatched, it may open up when
the vehicle is in motion and block your view.
There is a risk of an accident.
Never unlatch the hood while driving. G
WARNING
Certain components in the engine
compartment may be very hot, e.g. the drive
system and radiator. Working in the engine
compartment poses a risk of injury.
If possible, let the drive system cool down and
only touch the following described
components. 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. G
WARNING
The engine compartment contains moving
components. Certain components, such as
the radiator fan, may continue to run or start
again suddenly when the ignition is off. There
is a risk of injury.
If you need to do any work inside the engine
compartment:
R switch off the ignition
R never reach into the area where there is a
risk of danger from moving components,
such as the fan rotation area
R remove jewelery and watches
R keep items of clothing and hair, for
example, away from moving parts G
WARNING
The engine is equipped with a transistorized
ignition system. Because of the high voltage,
it is dangerous to touch any components
(ignition coils, spark plug sockets, diagnostic
socket) of the ignition system:
R with the engine running
R while starting the engine
R when the ignition is switched on and the
engine is turned manually G
WARNING
When the hood is open and the windshield
wipers are set in motion, you can be injured
by the wiper linkage. There is a risk of injury.
Always switch off the windshield wipers and
the ignition before opening the hood.
! Make sure that the windshield wipers are
not folded away from the windshield. You
could otherwise damage the windshield
wipers or the hood.
Do not touch the following when the ignition
is switched on:
R ignition coils
R spark plug connectors
R test socket 200
Engine compartmentMaintenance and care

Fuel
Important safety notes G
WARNING
Fuel is highly flammable. If you handle fuel
incorrectly, there is a risk of fire and
explosion.
You must avoid fire, open flames, creating
sparks and smoking. Switch off the engine
and, if applicable, the auxiliary heating before
refueling. G
WARNING
Fuel is poisonous and hazardous to health.
There is a risk of injury.
You must make sure that fuel does not come
into contact with your skin, eyes or clothing
and that it is not swallowed. Do not inhale fuel
vapors. Keep fuel away from children.
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.
Tank capacity Total capacity
All models
25.4 US gal
(96.0 l) Of which reserve
All models
Approx.
3.7 US gal (14.0 l) Gasoline (EN 228)
Fuel grade
!
Do not use diesel to refuel vehicles with a
gasoline engine. Even small amounts of the
wrong fuel result in damage to the fuel
system and engine.
! 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.
! To ensure the longevity and full
performance of the engine, only premium-
grade unleaded gasoline may be used.
If there is no premium-grade unleaded
gasoline available and regular unleaded
gasoline must be used, please observe the
following precautions:
R only fill the fuel tank to half full with
regular unleaded gasoline and fill the rest
with premium-grade unleaded gasoline
as soon as possible.
R do not drive at the maximum speed.
R avoid sudden acceleration.
R if the vehicle is carrying a light load, e.g.
two passengers without luggage, do not
allow the engine to rev above 3000 rpm.
R if the vehicle is fully loaded or is being
operated in mountainous terrain, do not
depress the accelerator pedal further
than Ôof the pedal travel.
! 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.
Only refuel using premium-grade unleaded
gasoline with a minimum octane rating of 91. Service products and filling capacities
259Technical data Z