2018 MERCEDES-BENZ G-CLASS engine overheat

There is a risk of an accident.
Wear suitable footwear to ensure correct
usage of the pedals.
GWARNING
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.
GWARNING
If the parking brake has not been fully
released when driving, the parking brake can:
Roverheat and cause a fire
Rlose 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 sta-
tionary.
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 other-
wise be significantly shortened. Do not use
the engine's full performance until it has
reached operating temperature.
!Mercedes-AMG vehicles: at low engine oil
temperatures below 68 ‡ (+20 †), the max-
imum engine speed is restricted in order to
protect the engine. To protect the engine and
maintain smooth engine operation, avoid driv-
ing at full throttle when the engine is cold.
Key positions
gTo remove the SmartKey
1Power supply for some consumers, such as
the windshield wipers
2Ignition (power supply for all consumers)
and drive position
3To 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
(
Ypage 193).
If the SmartKey is in position gin the ignition
lock for a longer period, 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.
XRemove the SmartKey when the engine is
switched off.
The starter battery could otherwise be dis-
charged.
If you cannot turn the SmartKey in the ignition
lock, the starter battery may not be charged
sufficiently.
XCheck the starter battery and charge it if nec-
essary (Ypage 248).
or
XJump-start the vehicle (Ypage 249).
You can only remove the SmartKey if:
Rthe SmartKey is in position gin the ignition
lock
Rthe automatic transmission selector lever is
in j
Driving105
Driving and parking
Z

XAvoid frequent acceleration or braking.
XHave all service and maintenance work car-
ried out at the specified intervals.
Fuel consumption also increases when driving in
cold weather, in stop-start traffic and in hilly ter-
rain.
Drinking and driving
GWARNING
Drinking and driving and/or taking drugs and driving are very dangerous combinations.
Even a small amount of alcohol or drugs can
affect your reflexes, perceptions and judg-
ment.
The possibility of a serious or even fatal acci-
dent is greatly increased when you drink or
take drugs and drive.
Do not drink or take drugs and drive or allow
anyone to drive who has been drinking or tak-
ing drugs.
Emission control
GWARNING
Combustion engines emit poisonous exhaust
gases such as carbon monoxide. Inhaling
these exhaust gases leads to poisoning. There
is a risk of fatal injury. Therefore never leave
the engine running in enclosed spaces with-
out sufficient ventilation.
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 if
they are serviced exactly in accordance with the
manufacturer's specifications. Always have
work on the engine carried out at a qualified
specialist workshop. Mercedes-Benz recom-
mends that you use an authorized Mercedes-
Benz Center for this purpose. In particular, work
relevant to safety or on safety-related systems
must be carried out at a qualified specialist
workshop.
The engine settings must not be changed under any circumstances. Furthermore, all specific
service work must be carried out at regular
intervals and in accordance with the Mercedes-
Benz service requirements. You can obtain cur- rent information concerning the servicing of
your vehicle at any time from a qualified spe-
cialist workshop. This could be an overview of
the
maintena
nce work or any additional main-
tenance work, for example.
Braking
Important safety notes
GWARNING
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 brak-
ing on a slippery road surface.
GWARNING
If you select the LOW RANGE off-road gear on
a slippery road surface, the wheels could lose traction:
Rif you remove your foot from the accelera-
tor pedal when driving
Rif off road ABS intervenes when braking
If the wheels lose traction. the vehicle can no
longer be steered. There is an increased dan-
ger of skidding and accidents.
Never select the LOW RANGE off-road gear
when driving on slippery road surfaces.
Information on the parking brake (
Ypage 123).
Downhill gradients
!On long and steep gradients, you must
reduce the load on the brakes by shifting to a
lower gear in good time. This allows you to
take advantage of the engine's braking effect.
This helps you to avoid overheating the
brakes and wearing them out excessively.
When you take advantage of engine braking, 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 war-
ranty.
Driving tips125
Driving an d parking
Z

This also applies if cruise control or DISTRONIC
PLUS is activated.
Heavy and light loads
GWARNING
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 the brakes have been subjected to a heavy
load, do not stop the vehicle immediately. Drive
on for a short while. This allows the airflow to
cool the brakes more quickly.
Wet roads
If driving in heavy rain for a prolonged period of
time without braking, there may be a delayed
reaction from the brakes when braking 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 vehicle
washed, brake firmly while paying attention to
the traffic conditions. This will warm up the
brake discs, thereby drying them more quickly
and protecting them against corrosion.
Limited braking performance on salt-
treated roads
If you drive on salted roads, a layer of salt resi-
due may form on the brake discs and brake
pads. This can result in a significantly longer
braking distance.
RIn order to prevent any salt build-up, apply the
brakes occasionally while paying attention to
the traffic conditions.
RCarefully depress the brake pedal and the
beginning and end of a journey.
RMaintain a greater distance to the vehicle
ahead.
Servicing the brakes
!The brake fluid level may be too low, if:
Rif the red brake warning lamp lights up in
the instrument cluster and
Ryou hear a warning tone while the engine is
running
Observe additional warning messages in the
multifunction display.
The brake fluid level may be too low due to
brake pad wear or leaking brake lines.
Have the brake system checked immediately. Consult a qualified specialist workshop to
arrange this.
!If the brake warning lamp lights up in the
instrument cluster and you hear a warning
tone even though the parking brake has been released, the brake fluid level may be too low.
Observe additional warning messages in the
multifunction display.
The brake fluid level may be too low due to
brake pad wear or leaking brake lines.
Have the brake system checked immediately. This work should be carried out at a qualified
specialist workshop.
!A function or performance test should only
be carried out on a 2-axle dynamometer. If
you wish to operate the vehicle on such a
dynamometer, please consult a qualified spe-
cialist workshop in advance. You could oth-
erwise damage the drive train or the brake
system.
!The ESP®system operates automatically. If
the parking brake is tested on a brake dyna-
mometer (for a maximum of ten seconds), the
engine and the ignition must be switched off.
Braking triggered automatically by ESP
®may
otherwise cause severe damage to the brake
system.
All checks and maintenance work on the brake
system must be carried out at a qualified spe-
cialist workshop.
126Driving tips
Driving and parking

RBefore tackling steep downhill gradients, shift
the automatic transmission to a low gear.
By doing so, you will use the braking effect of
the engine to reduce the speed. 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.
RObserve the notes on driving in mountainous
terrain (Ypage 132).
RCheck that the service brake is working nor-
mally after a long downhill stretch.
When driving at speeds below 37 mph
(60 km/h), off-road ABS is activated and the
front wheels lock cyclically during braking. The
digging-in effect achieved in the process
reduces the stopping distance on off-road ter-
rain. This limits steering capability.
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. Change into a lower
gear in good time on long and steep downhill
gradients.
This is especially important if the vehicle is
laden. 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 20 mph (30 km/h).
Do not activate cruise control on off-road jour-
neys.
Important safety notes
Cruise control can neither reduce the risk of an
accident if you fail to adapt your driving style nor override the laws of physics. Cruise control can-
not take into account the road, traffic and
weather conditions. Cruise control is only an
aid. You are responsible for maintaining a safe
distance to the vehicle in front, for vehicle
speed, for braking in good time and for staying in
lane. Do not use cruise control:
Rin road and traffic conditions that do not allow
you to maintain a constant speed, e.g. in
heavy traffic, on winding roads or on rough
terrain
Ron slippery road surfaces. Braking or accel-
erating could cause the drive wheels to lose
traction and the vehicle could then skid
Rin 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.
iThe speed indicated in the speedometer
may differ slightly from the speed stored.
Cruise control lever
:Activates or increases speed
;Activates or reduces speed
=Deactivates cruise control
?Activates at the current speed/last stored
speed
When you activate cruise control, the stored
speed is shown in the multifunction display for
five seconds.
Speedometer with segments: when cruise
control is activated, the segments from the
stored speed to the end of the scale light up.
Storing, maintaining and calling up a
speed
Storing and maintaining the current
speed
You can store the current speed if you are driv-
ing faster than 20 mph (30 km/h).
Driving systems133
Driving and parking
Z

This also applies if you have activated cruise
control or the speed limiter.
XIf necessary, shift the transfer case toLOW
RANGE (Ypage 149).
This will use the braking effect of the engine,
so that less braking will be required to main-
tain 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
permitted speed is. Observe the maximum per-
missible speed in the relevant country.
For certain Mercedes-Benz vehicles, the maxi-
mum permissible rear axle load is increased
when towing a trailer. See the "Technical data"
section to find out whether this applies to your
vehicle (
Ypage 291). In the event of increased
rear axle load, the car/trailer combination may
not exceed a maximum speed of 60 mph
(100 km/h) for reasons concerning the operat-
ing permit. This also applies in countries in
which the maximum permissible speed for car/ trailer combinations is greater than 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 con-
sume more fuel.
Driving tips
RMaintain a greater distance from the vehicle
in front than when driving without a trailer.
RAvoid braking abruptly. If possible, brake gen-tly at first to allow the trailer to run on. Then,
increase the braking force rapidly.
RThe values given for gradient-climbing capa-
bilities from a standstill refer to sea level.
When driving in mountainous areas, note that
the power output of the engine and, conse-
quently, the vehicle's gradient-climbing capa-
bility, decreases with increasing altitude.
If the trailer swings from side to side:
XDo not accelerate.
XDo not counter-steer.
XBrake if necessary.
Assembling the ball coupling
GWARNING
The ball coupling can be damaged if the nut on
the ball coupling is tightened using the incor-
rect torque. As a result, the trailer may
detach. There is a risk of an accident.
Immediately after installing, have the tighten-
ing torque checked at a qualified specialist
workshop.
!Mercedes-Benz recommends that you only
use ball couplings tested and approved for
use on Mercedes-Benz vehicles. This helps to avoid damage to the vehicle.
Observe the manufacturer's installation
instructions if you use a ball coupling other
than the one supplied.
XSlide ball coupling :through the hole in ball
coupling carrier bar ;to the stop.
XSlide lock washer ?onto the thread of ball
coupling =to the stop.
XScrew on nut Aas far as it will go.
Towing a trailer155
Driving and parking
Z

Towing a trailer
There are several legal requirements for towing
a trailer, e.g. the maximum permissible speed.
Make sure that your car/trailer combination
complies with the local regulations:
Rin your place of residence
Rat your destination
The police and local authorities can provide reli- able information.
In order to accumulate driving experience and
accustom yourself to the new handling charac-
teristics, practice the following at a location
where there is no traffic:
RCornering
RStopping
RBacking up
Before driving, check the following:
RTrailer tow hitch
RSafety switch for braked trailers
RSafety chains
RElectrical connections
RLighting system
RWheels and tires
RLoad-securing measures
Adjust the exterior mirrors to provide an unob-
structed view of the rear section of the trailer.
Trailers with electronically controlled
brakes: pull away carefully in the vehicle/trailer
combination, brake manually using the brake
controller and check whether the brakes func-
tion correctly.
Check the load securing measures on a regular
basis.
When towing a trailer, your vehicle's handling
characteristics will be different in comparison
with when driving without a tra
iler.
The vehicle/trailer combination:
Ris heavier
Ris restricted in its acceleration and gradient-
climbing capability
Rhas an increased braking distance
Ris affected more by strong crosswinds
Rdemands more sensitive steering
Rhas a larger turning radius
Avoid sudden steering movements.
Avoid braking abruptly. If possible, brake gently
at first to allow the trailer to run on. Then,
increase the braking force rapidly. When overtaking, pay particular attention to the
extended length of your vehicle/trailer combi-
nation.
Due to the length of the vehicle/trailer combi-
nation, you require additional road space when
overtaking before you can change back to the
original lane.
If the automatic transmission repeatedly shifts
between gears on uphill or downhill gradients,
shift to a lower gear.
Driving in a lower gear and at a reduced speed
decreases the risk of engine damage.
Avoid constant braking. Otherwise, the vehicle
brakes and possibly also the trailer brakes may
overheat.
When driving downhill, shift to a lower gear to
utilize the engine's braking effect.
If the coolant temperature increases dramati-
cally while the air-conditioni ng s
ystem is
switched on, switch off the air-conditioning sys- tem.
Coolant heat can also be dissipated by opening
the windows and switching the ventilation
blower and the interior temperature to the high-
est level.
Decoupling a trailer
GWARNING
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.
!Do not disconnect a trailer with an engaged
overrun brake. Otherwise, your vehicle could
be damaged by the rebounding of the overrun
brake.
XApply the parking brake.
XMake sure that the automatic transmission is
set to position P.
XSecure the vehicle and trailer against rolling
away.
XClose all doors, including the rear door.
XRemove the trailer cable.
XRemove the safety chains, if there are any.
XUncouple the trailer.
158Towing a trailer
Driving an d parking

Coolant temperature gauge
GWARNING
Opening the hood when the engine is over-
heated 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.
!If the coolant temperature is too high, a dis-
play message is shown.
If the coolant temperature display is in the
area marked in red, do not continue driving.
Otherwise, the engine will be damaged.
The coolant temperature gage is in the instru-
ment cluster on the right-hand side (
Ypage 32).
Under normal operating conditions and at the
correct coolant level, the gauge may rise to the
H marking.
Operating the on-board computer
Overview
:Multifunction display
;Switches on the Voice Control System (see
the separate operating instructions)
=Right control panel
?Left control panel
ABack button
XTo activate the on-board computer: turn
the SmartKey to position 1in the ignition
lock (
Ypage 105).
You can control the multifunction display and
the settings in the on-board computer using the
buttons on the multifunction steering wheel.
Left control panel
=
;RCalls up the menu and menu bar
9
:Press briefly:
RScrolls in lists
RSelects a submenu or function
RIn the Audiomenu: selects the
previous or next station, when the
preset list or station list is active,
or an audio track or video scene
RIn the Tel(telephone) menu:
switches to the phone book and
selects a name or telephone num-
ber
9
:Press and hold:
RIn the Audiomenu: selects a pre-
set list or a station list in the
desired frequency range or an
audio track or video scene using
rapid scrolling
RIn the Tel(Telephone) menu:
starts rapid scrolling if the phone
book is open
aRConfirms a selection/display mes-
sage
RIn the Tel(Telephone) menu:
switches to the phone book and
starts dialing the selected number
Right control panel
~RRejects or ends a call
RExits phone book/redial memory
6RMakes or accepts a call
RSwitches to the redial memory
W
XRAdjusts the volume
Displays and operation161
On-board computer and displays
Z

Display messagesPossible causes/consequences andMSolutions
?
CoolantToo HotSto pVehicl eTur nEngine Off
The coolan tis to ohot .
A warning tone also sounds.
GWARNIN G
Do no tdrive when your engin eis overheated. This can caus esom e
fluids whic hmay hav eleaked int oth eengin ecompartmen tto catch
fire.
Steam from th eoverheate dengin ecan also caus eserious burn swhic h
can occur jus tby opening th ehood.
There is aris kof injury.
XPull ove rand stop th evehicl esafely and switch off th eengine, pay-
ing attention to roa dand traffic conditions.
XSecur eth evehicl eagainst rollin gaway (Ypage 122).
XLeaveth evehicl eand keep asaf edistanc efrom th evehicl euntil th e
engin ehas cooled down .
XMakesur ethat th eair supply to th eengin eradiato ris no tblocked,
e.g. by snow, slus hor ice .
XDo no tstart th eengin eagain until th edisplay message goe sout and
th ecoolan ttemperature is belo wtheH marking .Otherwise ,th e
engin ecould be damaged.
XPay attention to th ecoolan ttemperature gauge .
XIf thetemperature increases again ,visit aqualified specialist work-
sho pimmediately.
Under normal operating condition sand at th ecorrec tcoolan tlevel,
th egauge may ris eto th eH marking .
The poly-V-belt may hav etorn .
XPull ove rand stop th evehicl esafely and switch off th eengine, pay-
ing attention to roa dand traffic conditions.
XChec kth epoly-V-belt .
If th epoly-V-belt is torn:
!Do no tcontinu edriving. The engin ecould otherwise overheat.
XConsult aqualified specialist workshop .
If th epoly-V-belt is not damaged :
XWait until thedisplay message disappear sbefore restarting th e
engine. Otherwise ,th eengin ecould be damaged.
XPay attention to th ecoolan ttemperature gauge .
XVisitaqualified specialist workshop .
Display messages181
On-board computer and displays
Z