engine overheat MERCEDES-BENZ M-Class 2014 W166 Owner's Manual

G
WARNING
If you switch off the ignitio nwhile 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.Y ou 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
maximu mengine speed is restricted in
order to protect the engine .To protec tthe
engine and maintain smooth engine
operation, avoid driving at full throttle when
the engine is cold. Key positions
SmartKey 000E
To remove the SmartKey
0005 Power supply for some consumers, such
as the windshield wipers
0006 Ignition (power supply for all consumers)
and drive position
0007 To start the engine
As soon as the ignition is switched on, all the
indicator lamps in the instrumentc luster light
up. If an indicator lamp does not go out after
starting the engine or lights up while driving,
see (Y page 318).
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.
X Remove the SmartKey when the engine is
switched off.
The starter battery could otherwise be
discharged.
If you cannot turn the SmartKey in the ignition
lock, the starter battery may not be charged
sufficiently.
X Check the starter battery and recharge if
necessary (Y page 388).
or
X Jump-start the vehicle (Y page 389). Driving
157Driving 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 medica lassistance
without delay.
R If fuel is swallowed, seek medical
assistance without delay.Don ot 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. !
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.
i Flexible Fuel vehicles can be recognized
by the Ethanol up to E85 sticker on the
inside of the fuel filler flap.
For further information on fuel and fuel quality
(Y page 444). Refueling
Opening/closing the fuel filler flap Pay attention to the important safety notes
(Y
page 173). 0002
To open the fuel filler flap
0003 To insert the fuel filler cap
0023 Fuel type to be used
0022 Tire pressure table
The fuel filler flap is unlocked or locked
automatically when you open or close the 174
RefuelingDriving and parking

i
On long journeys at a constant speed, e.g.
on the highway, only the bar for Constantwill change.
i The ECO display summaries 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.
Further information on the ECO display
(Y page 267). 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.T his 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
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.N ever
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 you have driven for a long time in heavy rain
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 or driven through
deep water.
You then 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
residue may form on the brake discs and
brake pads. This can result in a significantly
longer braking distance.184
Driving tipsDriving and parking

angle of 45°. Note that the climbing ability
of your vehicle depends on the terrain
conditions.
R When driving down an incline, make use of
the engine's braking effect. Observe the
engine speed; do no toverrev the engine.
R Drive slowly.
R Avoid high engine speeds. Drive at
appropriate engine speeds (maximum
3,000 rpm).
R Use the left-hand paddle shifter to shift into
a lower gearing ood time on long and steep
downhill gradients.
R Check the brakes after prolonged off-road
driving.
i Hill start assist will aid you when pulling
away on a hill.
For further information about hill start
assist, see (Y page 161).
Do not switch to transmission position N
when driving off-road. If you try to brake the
vehicle using the service brake, you could
lose control of the vehicle. If the gradient is
too steep for your vehicle, drive back down in
reverse gear.
Always observe the approach/departure
angle values (Y page 454).
Maximu mgradient-climbing capability Always observe the maximum gradient
climbing ability values (Y page 455).
Hilltops When driving up an uphill gradient, slightly
reduce pressure on the accelerator
immediately before reaching the brow of the
hill .Use the vehicle's own impetus to drive
over the top of the hill.
This style of driving prevents:
R the vehicle from lifting off the ground on the
brow of a hill
R the vehicle from traveling too quickly down
the other side 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). Driving systems
191Driving and parking Z

Deactivating cruise control
There are several ways to deactivate cruise
control:
X
Briefly press the cruise control lever
forwards 0002.
or
X Brake.
Cruise control is automatically deactivated if:
R you engage the electric parking brake.
R you are driving at less than 20 mph
(30 km/h).
R ESP ®
intervenes or you deactivate ESP ®
.
R you activate DSR.
R you shift the transmissio nto position N
while driving.
If cruise control is deactivated, you will hear
a warning tone. You will see the CruiseControl Off message in the multifunction
display for approximately five seconds.
i When you switch off the engine, the last
speed stored is cleared. DISTRONIC PLUS
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.
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 when
driving, the radar sensor system must be:
R activated(Y page 276)
R 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 RadarS ystem". The radar
sensor is intended fo ruse in an automotive
radar system only. Removing, tampering
with, or altering the device will void any
warranties, and is not permitted by the 194
Driving systemsDriving and parking

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.
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 frontt han 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 installed and secured
correctly it can become detached while the
vehicle is in motion and fall onto the road.
There is a risk of 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 0002in the direction of the
arrow, out of the ball coupling recess.
X Place protective cap 0002in the ball coupling
recess. Towing
atrailer
255Driving an d parking Z

R
Secure any objects on the traile rto 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.
Al ower 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
atrailer 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 overru nbrake
is engaged. G
WARNING
Vehicles with level control:
The vehicle is lowered as soon as you
disconnect the trailer cable. This could result
in yourl imbs or those of other people that are
betwee nthe 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 disconnectt he 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. 258
Towing
atrailerDriving an d parking

Displays and operation
Instrument cluster
Instrument cluster: miles
0002
Speedometer with segments (Y page 264)
0003 Fuel gauge
0023 Tachometer (Y page 264)
0022 Coolant temperature ( Ypage 263)
0020 Multifunction display (Y page 265)
0021 Instrumen tcluster lighting (Y page 263) Instrument cluster lighting
The lighting in the instrumen tcluster, 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 0006,0016or
000D, the brightness is dependent upon
the brightness of the ambien tlight.
i The light sensor in the instrumen tcluster
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 compartmen tcould 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.
! Adisplay message is shown if the coolant
temperature is too high. Displays and operation
263On-board computer and displays Z

Display messages Possible causes/consequences and
0001 Solutions
000E
Coolant Too Hot
Stop Vehicle Turn
Engine Off The coolan
tis too hot.
Aw arning tone also sounds.
G WARNING
Do no tdrive when youre ngine is overheated. Thi scan cause some
fluids which may have leaked into the engine compartmen tto
catch fire.
Stea mfrom 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 (Y page 179).
X Waitu ntil the engine has cooled down.
X Make sure tha tthe 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 †). 000B The battery is not being charged.
Aw
arning tone also sounds.
Possible causes are:
R a defective alternator
R a torn poly-V-belt
R a malfunction in the electronics
X Pull ove rand stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Ope nthe 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
299On-board computer and displays Z

Problem Possible causes/consequences and
0001 Solutions
000E
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 179).
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 367).
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
under 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. 000E
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 whe nyour 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
327On-board computer and displays Z