2011 MERCEDES-BENZ G550 engine overheat

! 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.
! 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.
i Only refuel with unleaded premium-grade
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 further information under
"Fuel" ( Y page 277), by consulting an
authorized Mercedes-Benz Center or
visiting http://www.mbusa.com (USA
only).
! 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.
Refueling
Fuel filler flap
When you open or close the vehicle with the
key, the fuel filler flap is automatically
unlocked or locked.
The position of the fuel filler cap is displayed
in the instrument cluster 8. The arrow
next to the filling pump indicates the side of
the vehicle. The fuel filler flap is located to the
rear on the right.
Fuel filler cap G 550 (example)
:To open the fuel filler flap;Tire pressure table=Fuel type?To insert the fuel filler cap
Opening
XSwitch off the engine.
i When the engine is running and the fuel
filler flap is open, the yellow reserve fuel
warning lamp and the = (USA only)
or ; (Canada only) engine diagnostics
warning lamp may light up.
For further information on warning and
indicator lamps in the instrument cluster,
see ( Y page 188).
XRemove the key from the ignition lock.XPress the fuel filler flap in the direction of
arrow :.
The fuel filler flap opens slightly.XOpen the fuel filler flap.132RefuelingDriving and parking

pedals. You could then no longer brake or
accelerate. This could lead to accidents and
injury.
Rolling with the engine switched offGWarning!
There is no power assistance for the steering
and the brake when the engine is not running.
Steering and braking requires significantly
more effort and you could lose control of the
vehicle and cause an accident as a result.
Do not turn off the engine while the vehicle is
in motion.
Exhaust check
GWarning
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.
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.
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
drive on for a short while. This allows the
airflow to cool the brakes more quickly.
Driving tips137Driving and parkingZ

Driving systems
Cruise control
Important safety 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, 2 or 3 in good
time. By doing so, you will make use of the
braking effect of the engine, which relieves
the load on the brake system and prevents
the brakes from overheating and wearing too
quickly.
Use cruise control only if road and traffic
conditions make it appropriate to maintain a
steady speed for a prolonged period. You can
store any road speed above 20 mph
(30 km/h).
GWarning
The cruise control is a convenience system
designed to assist the driver during vehicle
operation. The driver is and must always
remain responsible for the vehicle's speed
and for safe brake operation.
Only use the cruise control if the road, traffic,
and weather conditions make it advisable to
travel at a constant speed.
R The use of the cruise control can be
dangerous on winding roads or in heavy
traffic because conditions do not allow safe
driving at a constant speed.
R The use of the cruise control can be
dangerous on slippery roads. Rapid
changes in tire traction can result in wheel
spin and loss of control.
R Deactivate the cruise control when driving
in fog.
The "Resume" function should only be
operated if the driver is fully aware of the
previously set speed and wishes to resume
this particular preset speed.
Cruise control lever:To store the current speed or a higher
speed;To store the current speed or a lower
speed=To deactivate cruise control?To call up the last speed stored
When you activate cruise control, the stored
speed is shown in the multifunction display
for five seconds.
If an DEF ®
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
DEF ®
display message:
XBriefly press the V, U , & or
* button on the multifunction steering
wheel.
or
XBriefly press the reset button on the
instrument cluster.
Storing and maintaining the current
speed
You can store the current speed if you are
driving faster than 20 mph (30 km/h).
Driving systems147Driving and parkingZ

Vehicle equipment
i This manual describes all the standard
and optional equipment of your vehicle
which was available at the time of
purchase. Country-specific differences are
possible. Please note that your vehicle may
not be equipped with all features
described. This also applies to safety-
relevant systems and functions.
Important safety notes
You will find an illustration of the instrument
cluster in the "At a glance" section
( Y page 26).
GWarning
A driver's attention to the road and traffic
conditions must always be his/her primary
focus when driving.
For your safety and the safety of others,
selecting features through the multifunction
steering wheel should only be done by the
driver when traffic and road conditions permit
it to be done safely.
Bear in mind that at a speed of just 30 mph
(approximately 50 km/h ), your vehicle is
covering a distance of 44 feet (approximately
14 m) every second.
GWarning!
No messages will be displayed if either the
instrument cluster or the multifunction
display is inoperative.
As a result, you will not be able to see
information about your driving conditions,
such as
R speed
R outside temperature
R warning/indicator lamps
R malfunction/warning messages
R failure of any systems
Driving characteristics may be impaired.
If you must continue to drive, do so with added
caution. Contact an authorized Mercedes-
Benz Center as soon as possible.GWarning
Malfunction and warning messages are only
indicated for certain systems and are
intentionally not very detailed. The
malfunction and warning messages are
simply a reminder with respect to the
operation of certain systems. They do not
replace the owner's and/or driver's
responsibility to maintain the vehicle's
operating safety. Have all required
maintenance and safety checks performed on
the vehicle. Bring the vehicle to an authorized
Mercedes-Benz Center to address the
malfunction and warning messages.
Displays and operation
Tachometer
The red band in the tachometer indicates the
engine's overrevving range.
! Do not drive in the overrevving range, as
this could damage the engine.
The fuel supply is interrupted to protect the
engine when the red band is reached.
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.
156Displays and operationOn-board computer and displays

The display messages and the corresponding symbol that indicate that the coolant level is
too low must not be ignored.Display messagesPossible causes/consequences and M Solutions?
Coolant Stop, Turn
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 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 messages175On-board computer and displaysZ

Display messagesPossible causes/consequences and M Solutions?The engine fan is defective.XAt coolant temperatures under 248 ‡ (120 †), drive to the next
qualified specialist workshop.XAvoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-and-go traffic.#The battery is not being charged.
Possible causes are:
R a defective alternator
R a torn poly-V-belt
R a malfunction in the electronicsXPull 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:
XVisit a qualified specialist workshop.The battery voltage is too low.XSwitch off electrical consumers that are not required.XHave the battery and alternator checked at a qualified specialist
workshop.The battery has been charged or the vehicle has been jump-
started.XHave the battery and alternator checked at a qualified specialist
workshop.4
Check oil level at
next gas stationThe engine oil level has dropped to a critical level.XCheck the oil level ( Y page 215).XIf necessary, add engine oil ( Y page 216).XHave the engine checked for leaks if you need to add engine oil
more often than usual.You have added too much engine oil. There is a risk of damaging
the engine or catalytic converter.XSiphon off excess engine oil until it is at the specified level.
Observe the legal requirements.176Display messagesOn-board computer and displays

Vehicle equipment
i This manual describes all the standard
and optional equipment of your vehicle
which was available at the time of
purchase. Country-specific differences are
possible. Please note that your vehicle may
not be equipped with all features
described. This also applies to safety-
relevant systems and functions.
Engine compartment
Hood
Opening the hood
GWarning
Do not pull the release lever while the vehicle
is in motion. Otherwise, the hood could be
forced open by passing air flow.
This could cause the hood to come loose and
injure you and/or others.
GWarning!
Do not open the hood when the engine is
overheated. You could be seriously injured.
Observe the coolant temperature gauge to
determine whether the engine may be
overheated. If you see flames or smoke
coming from the engine compartment, move
away from the vehicle. Wait until the engine
has cooled. If necessary, call the fire
department.
GWarning!
You could be injured when the hood is open –
even when the engine is turned off.
Parts of the engine can become very hot. To
prevent burns, let the engine cool completely
before touching any components on the
vehicle. Comply with all relevant safety
precautions.
GWarning
To help prevent personal injury, stay clear of
moving parts when the hood is open and the
engine is running.
The radiator fan may continue to run for
approximately 30 seconds or may even
restart after the engine has been turned off.
Stay clear of fan blades.
GWarning
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
XMake sure that the windshield wipers are
switched off.GWarning
The windshield wipers and wiper linkage
could be set in motion.
When the hood is open, you or others could
be injured by the wiper linkage.
Make sure that the windshield wipers are
switched off and that the SmartKey has been
pulled out of the ignition lock before opening
the hood.
The release lever on the hood is in the footwell
on the left-hand side of the vehicle when
viewed in the direction of travel.
214Engine compartmentMaintenance and care

if the coolant temperature display indicates
that the coolant is overheated.
R do not remove the pressure cap on the
coolant reservoir if the coolant temperature
is above 158 ‡ (70 †). Allow the engine to
cool down before removing the cap. The
coolant reservoir contains hot fluid and is
under pressure.
R using a rag, slowly turn the cap
approximately 1
/ 2 turn to relieve excess
pressure. If opened immediately, scalding
hot fluid and steam will be blown out under
pressure.
R do not spill antifreeze on hot engine parts.
Antifreeze contains ethylene glycol which
may burn if it comes into contact with hot
engine parts.
The coolant expansion tank is located in the
engine compartment on the right when
viewed in the direction of travel.XSlowly turn cap : half a turn counter-
clockwise and allow excess pressure to
escape.XTurn cap : further counter-clockwise and
remove it.
If the coolant is at the level of marker bar
= in the filler neck when cold, there is
enough coolant in coolant expansion
tank ;.
If the coolant is approximately 0.6 in
(1.5 cm) above marker bar = in the filler
neck when warm, there is enough coolant
in coolant expansion tank ;.XIf necessary, add coolant that has been
tested and approved by Mercedes-Benz.XReplace cap : and turn it clockwise as far
as it will go.
For further information on coolant, see
( Y page 280).
Windshield washer system and
headlamp cleaning system
The washer fluid reservoir is used for both the
windshield washer system and the headlamp
cleaning system.
GWarning
Washer solvent/antifreeze is highly
flammable. Do not spill washer solvent/
antifreeze on hot engine parts, because it may
ignite and burn. You could be seriously
burned.
! At temperatures below freezing, always
fill the washer fluid container with a mix of
windshield washer concentrate and
antifreeze additive. There is otherwise a
risk of damaging the windshield washer
system/headlamp cleaning system.
! Only use washer fluid concentrate which
is suitable for plastic lenses. Unsuitable
washer fluid concentrate could damage the
plastic lenses of the headlamps.
! Do not add distilled or de-ionized water to
the washer fluid container. Otherwise, the
level sensor may be damaged.
i Add windshield washer concentrate, e.g.
MB SummerFit, to the washer fluid all year
round.
218Engine compartmentMaintenance and care