engine overheat MERCEDES-BENZ GLS 2019 Owners Manual

Notes on breaking-in a new vehicle
Important safety notes
The sensor system of some driving and driving
safety systems adjusts automatically while a
certain distance is being driven after the vehicle has been delivered or after repairs. Full system
effectiveness is not reached until the end of this
teach-in procedure.
New and replaced brake pads and discs only
reach their optimum braking effect after several hundred kilometers of driving. Compensate for
this by applying greater force to the brake pedal. The first 1000 miles (1500 km)
The more you look after the engine when it is
new, the more satisfied you will be with its per-
formance in the future. R You should therefore drive at varying vehicle
and engine speeds for the first 1000 miles
(1500 km).
R Avoid heavy loads, e.g. driving at full throttle,
during this period.
R Change gear in good time, before the tach-
ometer needle is 00C3of the way to the red area
of the tachometer.
R Do not manually shift to a lower gear to brake
the vehicle.
R Try to avoid depressing the accelerator pedal
beyond the point of resistance (kickdown).
Additional breaking-in notes for Mercedes-AMG
vehicles:
R Do not drive faster than 85 mph (140 km/h)
for the first 1,000 miles (1,500 km).
R Only allow the engine to reach a maximum
engine speed of 4,500 rpm briefly.
R Change gear in good time.
R Ideally, for the first 1,000 miles (1,500 km),
drive in the Comfortdrive program.
After 1000 mile s(1500 km), you can increase
the engine speed gradually and accelerate the
vehicle to full speed.
You should also observe these notes on break-
ing in if the engine or parts of the drive train on your vehicle have been replaced.
Always observe the maximum permissible
speed. Driving
Important safety notes
G
WARNING
Objects in the driver's footwell can restrict the pedal travel or obstruct a depressed pedal.
The operating and road safety of the vehicle is
jeopardized. There is a risk of an accident.
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 and do not place floormats on
top of one another. 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. Driving
139Driving and pa rking Z

In addition to driving style, the actual consump-
tion is affected by other factors, such as:
R load
R tire pressure
R cold start
R choice of route
R electrical consumers switched on
These factors are not included in the ECO dis-
play.
An economical driving style specially requires
driving at moderate engine speeds.
Achieving a higher value in the categories
"Acceleration" and "Constant":
R observe the gearshift recommendations.
R drive the vehicle in the Comfortdrive pro-
gram.
On long journeys at a constant speed, e.g. on the highway, only the outer area for "constant" will
change.
The ECO display summarizes the driving style
from the start of the journey to its completion.
Therefore, there are more marked changes in
the outer areas at the start of a journey. On lon-
ger journeys, there are fewer changes. For more
marked changes, perform a manual rest
(Y page 234).
For further information on the ECO display, see (Y page 234). 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 brak-
ing on a slippery road surface.
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.
Do not depress the brake pedal continuously
while the vehicle is in motion, e.g. causing the
brakes to rub by constantly applying light pres-
sure to the pedal. This results in excessive and
premature wear to the brake pads.
Use the left-hand steering wheel paddle shifter
to shift into a lower gear in good time on long
and steep downhill gradients. This is especially
important if the vehicle is laden.
This also applies if you have activated cruise
control, the limiter or Active Distance Assist
DISTRONIC.
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 sys-
tem and prevents the brakes from overheating
and wearing too quickly.
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. 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 you have driven for a long time in heavy rain
without braking, there may be a delayed reac-
tion from the brakes when braking for the first Driving tips
163Driving and parking Z

Further information on driving safety systems
(Y page 66). 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 down-
hill 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 con-
ditions make it appropriate to maintain a steady speed for a prolonged period. You can store anyroad speed above 20 mph (30 km/h).
i Cruise control should not be activated when
driving off-road.
Important safety notes If you fail to adapt your driving style, cruise con-
trol can neither reduce the risk of an accident
nor override the laws of physics. Cruise control
cannot take into account the road, traffic and
weather conditions. Cruise control 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 your lane.
Do not use cruise control:
R in road and traffic conditions which do not
allow you to maintain a constant speed, e.g. in
heavy traffic or on winding roads
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
If there is a change of drivers, advise the new
driver of the speed stored. Cruise control lever 0043
Activates or increases speed
0044 Activates or reduces speed
0087 Deactivates cruise control
0085 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.
Activation conditions To activate cruise control, all of the following
activation conditions must be fulfilled:
R the electric parking brake must be released.
R you are driving faster than 20 mph (30 km/h).
R ESP ®
must be active, but not intervening.
R the transmission must be in position 005B.
R DSR must be deactivated.
R the Offroad Plus drive program must be deac-
tivated (vehicles with the Off-road Engineer-
ing Package).
Storing, maintaining and calling up a
speed Storing and maintaining a speed
X Accelerate the vehicle to the desired speed.
X Briefly press the cruise control lever up 0043or
down 0085.
X Remove your foot from the accelerator pedal.
Cruise control is activated. The vehicle auto-
matically maintains the stored speed.
i Cruise control may be unable to maintain
the stored speed on uphill gradients. The
stored speed is resumed when the gradient
evens out. Cruise control maintains the Driving systems
171Driving and parking Z

stored speed on downhill gradients by auto-
matically applying the brakes.
Storing or calling up a speed G
WARNING
If you call up the stored speed and it differs
from the current speed, the vehicle acceler-
ates or decelerates. If you do not know the
stored speed, the vehicle could accelerate or brake unexpectedly. There is a risk of an acci-
dent.
Pay attention to the road and traffic condi-
tions before calling up the stored speed. If you do not know the stored speed, store the
desired speed again.
X Briefly pull the cruise control lever towards
you 0087.
X Remove your foot from the accelerator pedal.
Cruise control is operational and when first
activated stores the current speed or regu-
lates the speed of the vehicle to the stored
speed.
Setting a speed Keep in mind that it may take a brief moment
until the vehicle has accelerated or braked to
the speed set.
X Press the cruise control lever up 0043for a
higher speed or down 0044for a lower speed.
X To adjust the set speed in 1 mph incre-
ments (1 km/h increments):
briefly press
the cruise control lever up 0043or down 0044to
the pressure point.
Every time the cruise control lever is pressed
up 0043 or down 0044the last speed stored is
increased or reduced.
X To adjust the set speed in 5 mph incre-
ments (10 km/h increments):
briefly press
the cruise control lever up 0043or down 0044
beyond the pressure point.
Every time the cruise control lever is pressed
up 0043 or down 0044the last speed stored is
increased or reduced.
i Cruise control is not deactivated if you
depress the accelerator pedal. For example, if
you accelerate briefly to overtake, cruise con-
trol adjusts the vehicle's speed to the last
speed stored after you have finished overtak-
ing. Deactivating cruise control There are several ways to deactivate cruise con-
trol:
X Briefly press the cruise control lever for-
wards 0043.
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 activate the Offroad Plus program (vehi-
cles with the Off-road Engineering Package)
R you shift the transmission to position 005C
while driving
If cruise control is deactivated, you will hear a
warning tone. You will see the Cruise Con‐ Cruise Con‐
trol Off
trol Off message in the multifunction display
for approximately five seconds.
i When you switch off the engine, the last
speed stored is cleared. Active Distance Assist DISTRONIC
General notes Active Distance Assist DISTRONIC regulates the
speed and automatically helps you maintain the
distance from the vehicle detected in front.
Vehicles are detected with the aid of the radar
sensor system. Active Distance Assist
DISTRONIC 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 theengine. This relieves the load on the brake sys-
tem and prevents the brakes from overheating
and wearing too quickly.
If Active Distance Assist DISTRONIC detects
that there is a risk of a collision with the vehicle
in front, you will be warned visually and audibly.
Active Distance Assist DISTRONIC cannot pre-
vent 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 172
Driving systemsDriving and parking

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. Notes on towing a trailer
General notes !
If you have a trailer tow hitch retrofitted,
changes to the cooling system and drive train may be necessary, depending on the vehicle
type.
If you have a trailer tow hitch retrofitted,
observe the anchorage points on the chassis
frame.
R Do not exceed the legally prescribed maxi-
mum speed for vehicle/trailer combinations
in the relevant country.
This lowers the risk of an accident.
R Only install an approved trailer coupling on
your vehicle.
More information on availability and installa-
tion can be obtained at any qualified special-
ist workshop.
R The bumpers of your vehicle are not suitable
for installing detachable trailer couplings.
R Do not install hired trailer couplings or other
detachable trailer couplings on the bumpers
of your vehicle.
R If you no longer need the ball coupling,
remove it from the ball coupling recess. This
will reduce the risk of damage to the ball cou-
pling.
When towing a trailer, set the tire pressure on
the rear axle of the towing vehicle for the max-
imum load. You will find the values in the tire
pressure table in the fuel filler flap of the vehicle (Y page 371).
Please note that when towing a trailer, the fol-
lowing driving systems have limited availability
or are not available at all:
R Parking Assist PARKTRONIC (Y page 189)
R Blind Spot Assist (Y page 207)
R Active Lane Keeping Assist (Y page 212)On vehicles without level control, the height of
the ball coupling will alter according to the load
placed on the vehicle. If necessary, use a trailer
with a height-adjustable drawbar.
You will find installing dimensions and loads
under "Technical data" (Y page 392).
Driving tips Also observe the notes on pulling away with a
trailer (Y
page 143).
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 for your trailer. Observe the
legally permissible maximum speed in the rele-
vant country.
For certain Mercedes-Benz vehicles, the maxi-
mum permissible rear axle load is increased
when towing a trailer. See "Technical data" to
find out whether this applies to your vehicle
(Y page 392). 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 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
with when driving without a trailer.
Use the left-hand steering wheel paddle shifter
to shift into a lower gear in good time on long
and steep downhill gradients.
This also applies if you have activated cruise
control or Active Distance Assist DISTRONIC.
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 sys-
tem 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. 222
Towing a trailerDriving and parking

Most U.S. states and all Canadian provinces
require by law:
R Safety chains between the towing vehicle and
the trailer. The chains should be cross-woundunder the trailer drawbar. They must be fas-
tened to the vehicle's trailer coupling, not to
the bumper or the axle.
Leave enough play in the chains to make tight
cornering possible.
R A separate brake system for certain types of
trailer.
R Safety switch for braked trailers. Check the
specific legal requirements applicable to your
state.
If the trailer becomes detached from the tow-
ing vehicle, the safety feature triggers the
trailer brakes. Towing a trailer
There are numerous legal requirements con-
cerning the towing of a trailer, e.g. speed restric-
tions. Make sure that your car/trailer combina- tion complies with the local regulations:
R in your place of residence
R in the location to which you are driving
The police and local authorities can provide reli-
able information.
Observe the following when towing a trailer:
R To gain driving experience and to become
accustomed to the new handling characteris-
tics, you should practice the following in a
traffic-free location:
- cornering
- stopping
- backing up
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 has electronically controlled
brakes, pull away carefully. Brake manually using the brake controller and check whether
the brakes function correctly.
R Secure any objects on the trailer to prevent
the cargo from slipping when the vehicle is in
motion.
R When you couple up a trailer, check at regular
intervals that the load is firmly secured. If the trailer is equipped with trailer lights and
brakes, check the trailer to ensure that these
are working.
R Bear in mind that the handling will be less
stable when towing a trailer than when driving
without one. Avoid sudden steering move-
ments.
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, do not brake suddenly, but instead
depress the brake pedal moderately at first sothat the trailer can activate its brakes. Then
increase the pressure on the brake pedal.
R If the automatic transmission repeatedly
shifts between gears on uphill or downhill gra-
dients, shift to a lower gear using the left-hand
steering wheel paddle shifter.
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 instal- led, the trailer brakes.
R If the coolant temperature increases dramat-
ically while the air-conditioning system is
switched on, switch off the air-conditioning
system.
Coolant heat can also be dissipated by open-
ing the windows and switching the ventilation blower and the interior temperature to the
highest level.
R When overtaking, pay particular attention to
the extended length of your vehicle/trailer
combination.
Due to the length of the vehicle/trailer com-
bination, you require additional road space in
relation to the vehicle you are overtaking
before you can change back to the original
lane. Towing a trailer
225Driving and parking Z

There is a short delay before a change in outside
temperature appears in the multifunction dis-
play. Coolant temperature gauge
G
WARNING
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 gauge is in the instru-
ment cluster on the right-hand side (Y page 37).
Under normal operating conditions and with the specified coolant level, the coolant temperature gauge may rise to the red marking. Operating the on-board computer
Overview 0043
Multifunction display
0044 Right control panel
0087 Left control panel
X To activate the on-board computer: turn
the SmartKey to position 0047in the ignition
lock.
You can control the multifunction display and
the settings in the on-board computer using the buttons on the multifunction steering wheel.
Vehicles with the COMAND multimedia system: you can find further information on the Voice
Control System in the separate operating
instructions.
Vehicles with the Audio 20 multimedia system:
you can find further information on voice-oper-
ated control for navigation in the manufactur-
er's operating instructions. Displays and operation
231On-board computer and displays Z

Display messages
Possible causes/consequences and
0050
0050Solutions 00AC
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, pay-
ing attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 158).
X Wait 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 gauge.
If the temperature increases again: X Visit a qualified specialist workshop immediately.
Under normal operating conditions and with the specified coolant
level, the coolant temperature may rise to 248 ‡ (120 †). 003D
See Operator's Man‐ See Operator's Man‐
ual ual The battery is not being charged.
A warning tone also sounds.
Possible causes are:
R a defective alternator
R a torn poly-V-belt
R a malfunction in the electronics
! Do not drive any further. Otherwise the engine may overheat.
X Pull over and stop the vehicle safely and switch off the engine, pay-
ing attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 158).
X Consult a qualified specialist workshop. Display
messages
259On-board computer and displays Z

Warning/
indicator
lamp
0051
0051 Signal type
Possible causes/consequences and 0050 0050Solutions 00AC
0051
The red coolant warning lamp comes on while the engine is running.
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 defective.
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 158).
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 324).
X If you have to add 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 snow,
slush or ice.
X Do not start the engine again until the coolant temperature is below 248 ‡
(120 †). Otherwise, the engine could be damaged.
X Drive to the nearest qualified specialist workshop.
X Avoid heavy loads on the engine as you do so, e.g. driving in mountainous terrain
and stop-and-go traffic. 00AC
0051
The red coolant warning lamp comes on while the engine is running.
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 158).
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 324).
X If you have to add 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 snow,
slush or ice. 284
Warning and indicator lamps in the instrument clusterOn-board computer and displays

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. Before
every trip, ensure that the hood is locked. G
WARNING
When opening and closing the hood, it may
suddenly fall into the closed position. There is a risk of injury to persons within range of
movement of the hood.
Open and close the hood only when no one is
within its range of movement. G
WARNING
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. 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 jewelry and watches
R keep items of clothing and hair, for exam-
ple, away from moving parts G
WARNING
The ignition system and the fuel injection sys- tem work under high voltage. If you touch
components which are under voltage, you
could get an electric shock. There is a risk of
injury.
Never touch components of the ignition sys-
tem or fuel injection system when the ignition is switched on.
Electrically live components include ignition
coils, spark plug connectors and the test socket. To ensure the flow of fresh air through the air
vents into the vehicle interior, please observe
the following notes (Y page 136):
Opening the hood G
WARNING
Certain components in the engine compart-
ment, such as the engine, radiator and parts
of the exhaust system, can become very hot.
Working in the engine compartment poses a
risk of injury.
Where possible, let the engine cool down and touch only the components described in the
following. 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 wip-
ers or the hood. Engine compartment
321Maintenance and care Z