2019 MERCEDES-BENZ GLS SUV coolant level

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

Where possible, let the engine cool down and
touch only the components described in the
following. G
WARNING
The cooling system is pressurized, particularly when the motor is warm. If you open the cap, you could be scalded if hot coolant sprays out.
There is a risk of injury.
Let the engine cool down before you open the
cap. Wear protective gloves and protective
eyewear when opening. Open the cap slowly
to release pressure.
The coolant level may only be checked and cool- ant refilled when the engine and engine coolingsystem have cooled down. G
WARNING
Windshield washer concentrate is highly flam- mable. If windshield washer concentrate getsonto hot components of the engine or the
exhaust system, it can ignite. There is a risk of
fire and injury.
Make sure that windshield washer concen-
trate is not spilled in the vicinity of the filler
neck.
Checking coolant level X
Park the vehicle on a level surface.
Only check the coolant level when the vehicle
is on a level surface and the engine has cooled
down.
X Turn the SmartKey to position 0048in the igni-
tion lock (Y page 140).
On vehicles with KEYLESS-GO, press the
Start/Stop button twice (Y page 142).X
Check the coolant temperature gauge in the
multifunction display.
The coolant temperature must be below
158 ‡ (70 †).
X Turn the SmartKey to position in the ignition
lock 0092(Ypage 140).
X On vehicles with KEYLESS-GO, press the
Start/Stop button (Y page 142).
X Press the Start/Stop button (Y page 142).
X Slowly turn cap 0043half a turn counter-clock-
wise and allow excess pressure to escape.
X Turn cap 0043further counter-clockwise and
remove it.
If the coolant is at the level of marker bar 0087
in the filler neck when cold, there is enough
coolant in coolant expansion tank 0044.
If the coolant level is approximately 0.6 in
(1.5 cm) above marker bar 0087in the filler neck
when warm, there is enough coolant in expan- sion tank 0044.
X If necessary, add coolant that has been tested
and approved by Mercedes-Benz.
X Replace cap 0043and turn it clockwise as far as
it will go.
For further information on coolant, see
(Y page 387).
Adding washer fluid to the windshield
washer system Example: washer fluid reservoir
X To open: pull cap0043upwards by the tab.
X Add the premixed washer fluid.
X To close: press cap 0043onto the filler neck
until it engages.
If the washer fluid level drops below the recom- mended minimum of 1 liter, a message appears in the multifunction display prompting you to
add washer fluid (Y page 273).324
Engine compartmentMaintenance and care

The coolant is a mixture of water and anti-
freeze/corrosion inhibitor. It is responsible for
the following:
R anti-corrosion protection
R antifreeze protection
R raising the boiling point
If the coolant has antifreeze protection down to -35 ‡ (-37 †), the boiling point of the coolant
during operation is approximately 266 ‡
(130 †).
The antifreeze concentrate/corrosion inhibitor
concentration in the engine cooling system
should:
R be at least 50%. This will protect the engine
cooling system against freezing down to
approximately -35 ‡ (-37 †).
R not exceed 55% (antifreeze protection down
to -49 ‡[-45 †]). Otherwise, heat will not be
dissipated as effectively.
Mercedes-Benz recommends an antifreeze/
corrosion inhibitor concentrate in accordance
with MB Specifications for Service Products
310.1.
i When the vehicle is first delivered, it is filled
with a coolant mixture that ensures adequate
antifreeze and anti-corrosion protection.
i The coolant is checked at specified intervals
at a qualified specialist workshop.
Filling capacities Model Capacity
Mercedes
‑AMG
vehicles Approx. 11.9 US qt
(11.3 l) GLS 550 4MATIC
Approx. 12.0 US qt
(11.4 l) All other models
Approx. 10.3 US qt
(9.7 l) Windshield washer system
Important safety notes G
WARNING
Windshield washer concentrate is highly flam- mable. If windshield washer concentrate getsonto hot components of the engine or the exhaust system, it can ignite. There is a risk of
fire and injury.
Make sure that windshield washer concen-
trate is not spilled in the vicinity of the filler
neck.
! Only MB SummerFit and MB WinterFit
washer fluid should be mixed together. The
spray nozzles may otherwise become
blocked.
Do not use distilled or de-ionized water. Other-
wise, the level sensor may give a false reading.
When handling washer fluid, observe the impor- tant safety notes on service products
(Y page 384).
At temperatures above freezing:
X Fill the washer fluid reservoir with a mixture of
water and windshield washer fluid, e.g. MB
SummerFit.
Add 1 part MB SummerFit to 100 parts water.
At temperatures below freezing:
X Fill the washer fluid reservoir with a mixture of
water and washer fluid, e.g. MB WinterFit.
For the correct mixing ratio refer to the infor- mation on the antifreeze reservoir.
i Add windshield washer fluid, e.g. MB Sum-
merFit or MB WinterFit, to the washer fluid all
year round. Climate control syste
m refrigerant
Important safety notes The climate control system of your vehicle is fil-
led with refrigerant R‑134a.
The instruction label regarding the refrigerant
type used can be found on the radiator cross
member.
! Only the refrigerant R‑134a and the PAG oil
approved by Mercedes-Benz may be used.
The approved PAG oil may not be mixed with
any other PAG oil that is not approved for
R-134a refrigerant. Otherwise, the climate
control system may be damaged.
Service work, such as refilling with refrigerant or
replacing component parts, may only be carried out by a qualified specialist workshop. All appli- 388
Service products and filling capacitiesTechni
cal data