engine overheat MERCEDES-BENZ G-CLASS SUV 2012 Owners Manual

G
WARNING
Unsuitable footwea rcan hinder correc tusage
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 set the automatic transmission to the
respective drive positions when the vehicle
is stationary.
Where possible, avoid spinning the drive
wheels when pulling away on slippery
roads. Otherwise, you could 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 temper-
atures (below +20 †), the maximum
engine speed is restricted in order to pro-
tect 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 key
1 Power supply for some consumers, such
as the windscreen wipers
2 Ignition (power supply for all consumers)
and drive position
3 To start the engine
i The indicator and warning lamps light up
in the instrument cluster when you switch
on the ignition. They go out when the
engine is running. This shows that the indi-
cator and warning lamps for each system
are operational.
i You can only remove the key if:
R the key is in position 0in the ignition
lock.
R the automatic transmission selector
lever is in P. Driving
143Driving and parking Z

drive short distances, you should take a 20
minute trip on a motorway or rural road at
least every 500km. Brakes
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.
This increases the risk of skidding and having
an accident.
Do not shift down for additional engine brak-
ing on a slippery road surface.
Downhill gradients On long and steep downhill gradients, espe-
cially if the vehicle is laden or towing a trailer,
you must select shift range
1,2or 3
(Y page 153) in good time.
i This also applies if you have activated
cruise control or SPEEDTRONIC.
This will use the braking effec tofthe engine,
so less braking will be required to prevent the
vehicle from gaining 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.
Heavy and light loads G
WARNING
The braking system can overheat if you leave
your foot on the brake pedal while driving.
This increases the braking distance and could
even cause the braking system to fail. There
is a risk of an accident.
Never use the brake pedal as a footrest.Do
not simultaneously depress both the brake
pedal and the accelerato rpedal while driving. If the brakes have been subjected to a heavy
load, do not stop the vehicle immediately, but
drive on for a short while. This allows the air-
flow to cool the brakes more quickly.
If the brakes have been used only moderately,
you should occasionally test their effective-
ness. To do this, brake more firmly from a
higher speed. This improves the grip of the
brakes.
Wet road surfaces
If driving in heavy rain for a prolonged period
of time without braking, there may be a
delayed reaction from the brakes when brak-
ing for the first time. This may also occur after
the vehicle has been washed.
You have to depress the brake pedal more
firmly. Maintain a greater distance from the
vehicle in front.
After driving on a wet road or having the vehi-
cle washed, brake firmly while paying atten-
tion to the traffic conditions .This will warm
up the brake discs, thereby drying them more
quickly and protecting them against corro-
sion.
Limited braking performance on salt-
treated roads If you drive on salt-treated roads, a layer of
salt may form on the brake discs and pads.
This can increase the braking distance con-
siderably.
R
Apply the brakes occasionally in order to
prevent any salt build-up. Ensure that you
do not endanger other road users when
doing so.
R Carefully depress the brake pedal at the
end of the journey and when starting the
next journey.
R Maintain a much greater distance to the
vehicle in front. Driving tips
165Driving and parking Z

Do not use cruise control:
R
in traffi cconditions 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 accel-
erating 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 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.
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 con-
ditions make it appropriate to maintain a
steady speed for a prolonged period. You can
store any road speed above 30 km/h.
Cruise control lever :
To activate or increase speed
; LIM indicator lamp
= To activate at the current speed/last
stored speed
? To activate or reduce speed
A To switch between cruise control and var-
iable SPEEDTRONIC
B To deactivate cruise control You can operate cruise control and variable
SPEEDTRONIC with the cruise control lever.
When you activate cruise control, the stored
speed is shown in the multifunction display
for five seconds.
If an AdBlue ®
display message is shown in the
multifunction display, you will no longer be
able to use the full range of cruise control
functions.
The full range of cruise control functions will
become available again once you confirm the
AdBlue ®
display message:
X Briefly press the V,U,&or
* button on the multifunction steering
wheel.
or
X Briefly press the reset button on the instru-
ment cluster.
The LIM indicator lamp on the cruise control
lever indicates which system you have selec-
ted:
R LIM indicator lamp off: cruise control is
selected.
R LIM indicator lamp on: variable SPEED-
TRONIC is selected.
Activation conditions To activate cruise control, all of the following
activation conditions must be fulfilled:
R
the parking brake must be released.
R you are driving faster than 30 km/h.
R ESP ®
must be switched on, but not inter-
vening.
R the transmission must be in position D.
R the cruise control function must be selec-
ted (Y page 175). 174
Driving systemsDriving and parking

Making adjustments in 10 km/h incre-
ments
:
To activate or increase speed
; LIM indicator lamp
= To activate at the current speed/last
stored speed
? To activate or reduce speed
A To switch between cruise control and var-
iable SPEEDTRONIC
B To deactivate cruise control
X Briefly press the cruise control lever
up : or down ?to beyond the pressure
point.
The lasts tored speed increases or decrea-
ses in 10 km/h increments.
Deactivating cruise control :
To activate or increase speed
; LIM indicator lamp
= To activate at the current speed/last
stored speed
? To activate or reduce speed A
To switch between cruise control and var-
iable SPEEDTRONIC
B To deactivate cruise control
There are several ways to deactivate cruise
control:
X Briefly press the cruise control lever for-
wards B.
or
X Brake.
or
X Briefly press the cruise control lever in the
directio nofarrowA.
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 30 km/h.
R ESP ®
intervenes or you deactivate ESP ®
.
R you shift the transmission to position N
while driving.
R G3 50 BlueTEC: you engage a differential
lock.
i The last speed stored is cleared when you
switch off the engine. SPEEDTRONIC
Important safety notes G
WARNING
The braking system can overheat if you leave
your foot on the brake pedal while driving.
This increases the braking distance and could
even cause the braking system to fail. There
is a risk of an accident.
Never use the brake pedal as a footrest .Do
not simultaneously depress both the brake
pedal and the accelerato rpedal while driving.
! Depressing the brake pedal constantly
results in excessive and premature wear to
the brake pads. 178
Driving systemsDriving and parking

If you fail to adapt yourd
riving style, SPEED-
TRONIC can neither reduce the risk of acci-
dent nor override the laws of physics. SPEED-
TRONIC cannot take account of road, weather
and traffic conditions. SPEEDTRONIC is only
an aid.Y ou 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 main-
tain 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. 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 continu-
ously.
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
A To switch between cruise control and var-
iable SPEEDTRONIC
B To deactivate variable SPEEDTRONIC
You can operate cruise control and variable
SPEEDTRONIC with the cruise control lever.
The LIM indicator lamp on the cruise control
lever indicates which system you have selec-
ted:
R LIM indicator lamp off: cruise control is
selected.
R LIM indicator lamp on: variable SPEED-
TRONIC is selected.
You can use the cruise control lever to limit
the speed to any speed above 30 km/hw hile
the engine is running.
Selecting variable SPEEDTRONIC :
To activate or increase speed
; LIM indicator lamp
= To activate at the current speed/last
stored speed
? To activate or reduce speed
A To switch between cruise control and var-
iable SPEEDTRONIC
B To deactivate cruise control
If you fail to adapt your driving style, SPEED-
TRONIC can neither reduce the risk of acci-
dent nor override the laws of physics. SPEED-
TRONIC cannot take account of road, weather
and traffic conditions. SPEEDTRONIC is only
an aid. You are responsible for the distance Driving systems
179Driving and parking Z

be warned visually and acoustically. DIS-
TRONIC PLUS cannot preven tacollision with-
out your intervention. An intermittent warn-
ing 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 recognise dangers
in time, cause an accident and injure yourself
and others.
If DISTRONIC PLUS is activated, the vehicle
brakes automatically in certain situations.
This can happe nunexpectedly, 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 activatio nconditions must be
fulfilled (Y page 184) and the radar sensor
system must be operational.
General notes DISTRONIC PLUS regulates the speed and
automatically helps you maintain the dis-
tance to the vehicle detected in front. DIS-
TRONIC PLUS brakes automatically so that
the set speed is not exceeded.
On long and steep downhill gradients, espe-
cially 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. 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 there is no vehicle in front, DISTRONIC
PLUS operates in the same way as cruise
control in the speed range between
30 km/ha
nd 200 km/h. If avehicle is driving
in front of you, DISTRONIC operates in the
speed range between 0km/h and
200 km/h.
Do not use DISTRONIC PLUS on roads with
steep gradients.
Cruise control lever :
To activate or increase speed
; To set the specified minimu mdistance
= LIM indicator lamp
? To activate at the current speed/last
stored speed
A To activate or reduce speed
B To switch between DISTRONIC PLUS and
variable SPEEDTRONIC
C To deactivate DISTRONIC PLUS
With the cruise control lever, you can operate
DISTRONIC PLUS and variable SPEED-
TRONIC.
X To switch between variable SPEED-
TRONIC and DISTRONIC PLUS: press the Driving systems
183Driving and parking Z

for a maximu
mload; see the tyre pressure
table in the fuel filler flap (Y page 325).
You will find installation dimensions and loads
in the technical data (Y page 350).
The maximum permissible trailer drawbar
noseweight on the ball coupling is:
R 140 kg (G-Class long-wheelbase version)
R 115 kg (G-Class Cabriolet)
However, the actual noseweight must not
exceed the value given on the trailer tow hitch
or trailer identification plates. The lowest
weight applies.
i When towing a trailer, set the tyre pres-
sure on the rear axle of the towing vehicle
for a maximum load; see the tyre pressure
table in the fuel filler flap (Y page 325).
Please note that when towing a trailer, PARK-
TRONIC (Y page 197) and Blind Spot Assist
(Y page 190) are only available with limita-
tions, or not at all.
i On vehicles without level control, the
height of the ball coupling will alter accord-
ing to the load placed on the vehicle. If nec-
essary, use a trailer with a height-adjusta-
ble drawbar.
Driving tips X
On long and steep downhill gradients,
select shift range 1,2or 3(Y page 153) 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 202).
This will use the braking effect of the
engine, so less braking will be required to
prevent the vehicle from gaining speed.
This relieves the load on the brake system
and prevents the brakes from overheating
and wearing too quickly. If you need addi-
tional 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 max-
imum permitted speed is. Observe the legally
prescribed maximum speed in the relevant
country.
For certain Mercedes-Benz vehicles, the max-
imum 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 utilise any of the added
maximum rear axle load when towing a trailer,
the vehicle/trailer combination may not
exceed a maximum speed of 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 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.
Driving tips
If the trailer swings from side to side:
X
Do not accelerate.
X Do not countersteer.
X Brake if necessary.
R Maintain a greater distance from the vehi-
cle 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, decrease with increas-
ing altitude. Towing
atrailer
207Driving an d parking Z

Display messages Possible causes/consequences and
M Solutions
?
Coolant Stop vehi‐
cle Switch engine
off The coolan
tis too hot.
Aw arning tone also sounds.
G WARNING
Never drive with an overheated engine. Driving when your engine
is overheated can cause som efluids which may have leaked into
the engine compartment to catch fire.
Steam fro manoverheated engine can cause serious burns which
can occur just by opening the bonnet.
There is a risk of injury.
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Secure the vehicle against rolling away (Y page 163).
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 frozen slush.
X Do not start the engine again until the display message goes out
and the coolant temperature is below 120 †. The engine may
otherwise be damaged.
X Pay attention to the coolant temperature display.
X If the temperature increases again, visi taqualified specialist
workshop immediately.
Under normal operating conditions and with the specified coolant
level, the coolant temperature may rise to 120 †. The poly-V-belt may have torn.
X
Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switc hoff the engine.
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 OK:
X Wai tuntil the display message disappears before restarting the
engine .The engine may otherwise be damaged.
X Pay attention to the coolant temperature display.
X Visit a qualified specialist workshop. 238
Display messagesOn-board computer and displays

Display messages Possible causes/consequences and
M Solutions
# The battery is no
tbeing charged.
Aw arning tone also sounds.
Possible causes:
R faulty alternator
R torn poly-V-belt
R a malfunction in the electronics
X Stop the vehicle immediately, paying attentio ntoroad and traf-
fic conditions, and switch off the engine.
X Open the bonnet.
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 OK:
X Visit a qualified specialist workshop. 4
Check eng. oil
lev. when next
refuelling The engine oil level has dropped to the minimum level.
Aw
arning tone also sounds.
X Chec kthe oil level when next refuelling, at the latest
(Y page 291).
X If necessary, top up the engine oil (Y page 293).
X Have the engine checked at a qualified specialist workshop if
the engine oil needs topping up more often than usual. 4
Engine oil level
Stop vehicle Turn
engine off The engine oil level is too low. There is a risk of engine damage.
X
Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Top up the engine oil (Y page 293) and check the oil level
(Y page 291). 4
Add
1 litre engine
oil when next refu‐
elling AMG vehicles: the engine oil level is too low.
X
Check the oil level when next refuelling, at the latest
(Y page 291).
X If necessary, top up the engine oil (Y page 293).
X Have the engine checked at a qualified specialist workshop if
the engine oil needs topping up more often than usual. 4
Cannot measure
engine oil level The measuring system is malfunctioning.
X Visit a qualified specialist workshop. Display messages
239On-board computer and displays Z

Problem Possible causes/consequences and
M Solutions
?
The red coolant warn-
ing lamp comes on
while the engine is run-
ning.
The coolant level is too low.
If the coolant level is correct, the airflow to the engine radiator
may be blocked or the electric engine radiator fan may be mal-
functioning.
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 Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Engage the parking brake.
X Leave the vehicle and keep a safe distance from the vehicle until
the engine has cooled down.
X Check the coolant level and top up the coolant, observing the
warning notes (Y page 293).
X If you have to top up the coolant frequently, have the engine
cooling system checked.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by frozen slush.
X Do not start the engine again until the coolant temperature is
below 120 †. The engine may otherwise be damaged.
X Drive to the nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in moun-
tainous terrain, and stop-start driving. ?
The red coolant warn-
ing lamp comes on
while the engine is run-
ning. A warning tone
also sounds.
The coolant temperature has exceeded 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.
Never drive with an overheated engine. Driving when your engine
is overheated can cause some fluids which may have leaked into
the engine compartment to catch fire.
Steam from an overheated engine can cause serious burns which
can occur just by opening the bonnet.
There is a risk of injury.
X Observe the additional display messages in the multifunction
display.
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Secure the vehicle against rolling away (Y page 163).Warning and indicator lamps in the instrument cluster
261On-board computer and displays Z