Get Maintenance and care -> Engine compartment Guide for Mercedes C Class 4 Door Fourth Generation (2014-2021)

372 Maintenance and care

Battery disconnection periods

Resetting the active bonnet

fied based on the actual operating conditions

and/or loads.

Examples of arduous operating conditions:

The ASSYST PLUS service interval display

can only calculate the service due date when

the battery is connected.

&

WARNING Risk of burns from hot com‐

ponent parts in the engine compartment

R

regular city driving with frequent intermedi‐

ate stops

Certain component parts in the engine com‐

partment can be very hot, e.g. the engine,

the cooler and parts of the exhaust system.

#

Note down the service due date displayed on

R

mainly short-distance driving

the instrument display before disconnecting

the battery (/ page 371).

R

frequent operation in mountainous terrain or

on poor road surfaces

#

Allow the engine to cool down and only

touch component parts described in

the following.

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when the engine is often left idling for long

periods

Engine compartment

Active bonnet (pedestrian protection)

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operation in particularly dusty conditions

Operation of the active bonnet (pedestrian

protection)

In certain accident situations, the actuation of

the active bonnet reduces the risk of injury to

pedestrians. The rear area of the bonnet is

raised by approximately 85 mm.

For the drive to the workshop, reset the actuated

active bonnet yourself (/ page 372).

After the active bonnet has been actuated,

pedestrian protection may be limited.

and/or if air-recirculation mode is frequently

used

In these or similar operating conditions, have the

interior air filter, engine air cleaner, engine oil

and oil filter etc. changed more frequently. The

tyres must be checked more frequently if the

vehicle is operated under increased loads. Fur‐

ther information can be obtained at a qualified

specialist workshop.

Have the full functionality of the active bonnet

restored in a qualified specialist workshop.

Maintenance and care 373

#

With your hand flat, push down active bonnet

1 in the area around the hinges on both

sides (arrows).

In doing so, the actuator is depressurised

and you may hear a hissing sound.

&

WARNING Risk of accident and injury

when opening and closing the bonnet

WARNING Risk of injury due to moving

parts

The bonnet may suddenly drop into the end

position.

There is a risk of injury for anyone in the bon‐

net's range of movement.

Components in the engine compartment may

continue running or start up suddenly, even if

the ignition is switched off.

Make sure of the following before performing

tasks in the engine compartment:

The engine bonnet must engage in position.

If the active bonnet can be raised slightly at

the rear in the area of the hinges, repeat the

step until it engages correctly.

#

Open or close the bonnet only when

there is nobody in the bonnet's range of

movement.

#

Switch the ignition off.

Never reach into the danger zone sur‐

#

rounding moving components, e.g. the

rotation area of the fan.

Remove jewellery and watches.

Keep items of clothing and hair away

from moving parts.

Opening and closing the bonnet

&

WARNING Danger of burns when open‐

ing the bonnet

#

&

WARNING Risk of accident due to driv‐

ing with the bonnet unlocked

#

If you open the engine bonnet when the

engine has overheated or during a fire in the

engine compartment, you could come into

contact with hot gases or other escaping

operating fluids.

The bonnet may open and block your view.

#

Never release the bonnet when driving.

&

WARNING Risk of injury from touching

components under voltage

#

Before every trip, ensure that the

engine bonnet is locked.

#

Before opening the bonnet, allow the

engine to cool down.

In the event of a fire in the engine com‐

partment, keep the engine bonnet

closed and call the fire service.

The ignition system and the fuel injection

system work under high voltage. You could

receive an electric shock.

#

374 Maintenance and care

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Never touch components of the ignition

system or the fuel injection system

when the ignition is switched on.

NOTE Plug-in hybrid

*

#

Observe the notes in the Supplement.

You could otherwise fail to recognise

dangers.

&

WARNING Risk of burns from hot com‐

ponent parts in the engine compartment

Opening the bonnet

Certain component parts in the engine com‐

partment can be very hot, e.g. the engine,

the cooler and parts of the exhaust system.

#

Allow the engine to cool down and only

touch component parts described in

the following.

&

WARNING Risk of injury from using the

windscreen wipers while the engine bon‐

net is open

#

Push handle 1 of the bonnet catch upwards

and lift the bonnet by approximately 40 cm.

When the engine bonnet is open, and the

windscreen wipers are set in motion, you can

be trapped by the wiper linkage.

Closing the bonnet

#

Lower the bonnet to a height of around

20 cm and then allow it to fall, applying a lit‐

tle force as you let it go.

#

Always switch off the windscreen wip‐

ers and ignition before opening the

engine bonnet.

#

To release the bonnet, pull on handle 1.

Maintenance and care 375

Park the vehicle on a level surface.

#

R

If the bonnet can still be lifted slightly, open

the bonnet again and close it with a little

more force until it engages correctly.

The engine has an oil dipstick. If not, the

engine oil level can be checked only with the

on-board computer (/ page 375) .

Pull oil dipstick 1 out and wipe off.

Slowly slide oil dipstick 1 into the guide

tube to the stop, and pull it out again after

approximately three seconds.

Depending on the engine, the oil dipstick may be

installed in the engine compartment in different

locations.

The waiting time before checking the oil level

when the engine is at normal operating tempera‐

ture is five minutes.

Engine oil

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oil level is correct: oil level is between 2

and 3.

Checking the engine oil level using the oil

dipstick

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oil level too low: oil level is at 3 or

below.

&

WARNING Risk of burns from hot com‐

ponent parts in the engine compartment

oil level too high: oil level is above 2.

#

Certain component parts in the engine com‐

partment can be very hot, e.g. the engine,

the cooler and parts of the exhaust system.

If the oil level is too low, top up with 1 litre of

engine oil.

If the oil level is too high, drain off excess

engine oil. Consult a qualified specialist

workshop.

#

Allow the engine to cool down and only

touch component parts described in

the following.

Checking the engine oil level using the on-

board computer

Requirements:

NOTE Plug-in hybrid

*

#

Observe the notes in the Supplement.

You could otherwise fail to recognise

dangers.

R

The engine has an oil level sensor. If not, the

engine oil level can be checked only with the

oil dipstick (/ page 375).

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the engine has been warmed up.

Requirements:

376 Maintenance and care

#

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Topping up engine oil

the vehicle is parked on a level surface.

The engine is running at idle speed.

Add 1 l of engine oil.

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Reduce engine oil level and the bar display

for indicating the oil level on the multifunc‐

tion display is orange and is above "max":

&

WARNING Risk of burns from hot com‐

ponent parts in the engine compartment

The engine oil level is determined during driving.

Determining the engine oil level can take up to

30 minutes with a normal driving style and even

longer with an active driving style.

Certain component parts in the engine com‐

partment can be very hot, e.g. the engine,

the cooler and parts of the exhaust system.

#

Drain off any excess engine oil that has been

added. To do so, consult a qualified specialist

workshop.

On-board computer:

4

#

Allow the engine to cool down and only

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For engine oil level turn on ignition

5

Service

Engine oil level

touch component parts described in

the following.

#

You will see one of the following messages on

the multifunction display:

Switch on the ignition to check the engine oil

level.

R

&

Engine oil level Measuring now: measure‐

ment of the oil level is not yet possible.

WARNING Risk of fire and injury from

engine oil

Engine oil level System inoperative: The oil

level sensor is defective or not connected.

#

If engine oil comes into contact with hot

component parts in the engine compart‐

ment, it may ignite.

#

Repeat the request after a maximum of

Consult a qualified specialist workshop.

30 minutes' driving.

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Engine oil level System currently unavail.

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Engine oil level OK and the bar display for

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Close the bonnet.

#

Make sure that no engine oil is spilled

next to the filler opening.

indicating the oil level on the multifunction

display is green and is between "min" and

"max": the oil level is correct.

#

Allow the engine to cool off and thor‐

oughly clean the engine oil from compo‐

nent parts before starting the vehicle.

R

Engine oil level Add 1.0 l and the bar display

for indicating the oil level on the multifunc‐

tion display is orange and is below "min":

Maintenance and care 377

Checking the coolant level

the vehicle is new or if you frequently drive

at high engine speeds.

NOTE Engine damage caused by an

incorrect oil filter, incorrect oil or addi‐

tives

*

&

WARNING Risk of burns from hot com‐

ponent parts in the engine compartment

#

Do not use engine oils or oil filters

which do not correspond to the specifi‐

cations explicitly prescribed for the

service intervals.

Follow the instructions on the service

interval display for changing the engine

oil and observe the prescribed change

intervals.

Certain component parts in the engine com‐

partment can be very hot, e.g. the engine,

the cooler and parts of the exhaust system.

#

Allow the engine to cool down and only

#

touch component parts described in

the following.

&

WARNING Risk of scalding from hot

coolant

#

Do not use additives.

If you open the cap, you could be scalded.

NOTE Damage caused by topping up too

much engine oil

*

#

Let the motor cool down before opening

the cap.

Too much engine oil can damage the engine

or the catalytic converter.

#

When opening the cap, wear protective

gloves and safety glasses.

#

Turn cap 1 anti-clockwise and remove it.

#

Have excess engine oil removed at a

qualified specialist workshop.

Top up the engine oil.

Replace cap 1 and turn it clockwise until it

engages.

#

Open the cap slowly to release pres‐

sure.

% Depending on driving style, the vehicle con‐

sumes up to 0.8 l of oil per 1000 km. The oil

consumption may be higher than this when

#

Check the oil level again (/ page 375).

378 Maintenance and care

#

Continue turning cap 1 anti-clockwise and

#

Allow the engine to cool down and only

touch component parts described in

the following.

remove it.

The coolant level is correct in the following

cases:

&

WARNING ‑ Risk of fire and injury due to

windscreen washer concentrate

R

if the engine is cold, the coolant is up to

marker bar 2.

Windscreen washer concentrate is highly

flammable. It could ignite if it comes into

contact with hot engine component parts or

the exhaust system.

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if the engine is warm, the coolant is up to

1.5 cm over the marker bar 2.

#

If necessary, top up with coolant that has

been approved for Mercedes-Benz.

#

Make sure that no windscreen washer

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Further information on coolant

concentrate spills out next to the filler

opening.

(/ page 437).

Topping up the windscreen washer system

#

Park the vehicle on a level surface.

#

&

WARNING Risk of burns from hot com‐

ponent parts in the engine compartment

Check the coolant temperature display in the

instrument cluster.

The coolant temperature must be below

70°C.

Slowly turn cap 1 anti-clockwise to release

overpressure.

Certain component parts in the engine com‐

partment can be very hot, e.g. the engine,

the cooler and parts of the exhaust system.

#

Maintenance and care -> Engine compartment for Your Mercedes C Class 4 Door Fourth Generation (2014-2021)

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