engine MERCEDES-BENZ C-CLASS CABRIOLET 2021 Repair Manual

Information on using a high-p
ressure cleaner &
WARNING Risk of an accident when
using high-pressure cleane rswith round-
spray nozzles
The wate r jet can cause extern ally invisible
damage.
Components damaged in this wa y may unex‐
pec tedly fail. #
Do not use a high-pressure cleaner with
round-spr aynozzles. #
Have damaged tyres or chassis parts
re placed immediatel y.To
avo id damage to yourvehicle, obser vethefo l‐
lowing when using a high-pressure cleaner:
R The key is at a minimum distance of 3 m
aw ay from theve hicle. Otherwise the boot lid
could open unintentionall y.
R Maintain a dis tance of at least 30 cm tothe
ve hicle.
R Vehicles with deco rative foil: Parts of your
ve hicle are co vered with a decorative foil. Maintain a dis
tance of at least 70 cm
between thefo il-c ove red parts of theve hicle
and the nozzle of the high-pressure cleaner.
Mo vethe high-pressure cleaner nozzle
around whilst cleaning. The waterte mp era‐
ture of the high-pressure cleaner must not
exc eed 60°C.
R Obser vethe information on the cor rect dis‐
ta nce in the equipment manufacturer's oper‐
ating instructions.
R Do not direct the nozzle of the high-pressure
cleaner directly at sensitive parts, such as
tyres, soft top, wind deflector net, gaps, elec‐
trical components, batteries, light sources
and ventilation slits. Wa
shing theve hicle byhand *
NO
TEEngine dama gedue towa ter
ing ress #
Take care not topoint thewate r jet
directly towa rdsth e air inlet grille below
th e bonn et. obser
vethe legal requ irements, e.g. in a number
of countries, washing byhand is only permitted
in specially designated wash ba ys. #
Use a mild cleaning agent, e.g. car shampoo. #
Washtheve hicle with luk ewarmwate r using
a soft car sponge. When doing so, do not
ex pose theve hicle todirect sunlight. #
Carefully hose theve hicle off with water and
dry using a chamois.
% Obse rveth e no tes on the care of car parts
(/ page 368). Note
s on paint work/matt finish paint work
care Obse
rveth e no tes on cleaning and care toavo id
damaging the paintwor k.
Pa int
R Insect remains: soak with insect remo ver and
ri nse off the treated areas af terw ards.
R Bird droppings: soak with water and rinse off
af te rw ards. 364
Maintenance and care

R
Tree resin, oils, fuels and greases: remo veby
ru bbing gently wi tha clo thsoaked in petro‐
leum ether or lighter fluid.
R Coolant and brake fluid: remo vewith a damp
clo thand clean water.
R Tarst ains: use tarre mo ver.
R Wax: use silicone remo ver.
R Do not attach sticke rs,fi lms or similar mate‐
ri als.
R Remo vedirt immediately, where possible.
Matt finish
R Only use care products appr ovedfor
Mercedes-Benz.
R Do not polish theve hicle and light-alloy
wheels.
R Only use car washes that cor respond tothe
latest engineering standards.
R Do not use car wash programmes with a final
hot wax treatment.
R Do not use paint cleane rs, buf fing or polish‐
ing products, gloss preser vers, e.g. wax. R
Alw ays ha vepaintwork repairs car ried out at
a qu alified specialist workshop. Note
s on cleaning decorative foils Obser
vethe no tes on matt finish care in the
ch ap ter "No tes on paintwork/matt finish paint‐
wo rkcare" (/ page 364). They also apply to
matt decorative foils.
Obser vethe no tes on cleaning decorative foils to
avo idvehicle damage.
Cleaning R For cleaning, use plenty of water and a mild
cleaning agent without additives or abrasive
subs tances, e.g. a car sha mpoo appr ovedfor
Mercedes-Benz.
R Remo vedirt immediatel y,where possible,
whilst avoiding rubbing too hard. There is
ot herwise a risk of damaging the decorative
fo il ir reparably.
R Ifth ere is dirt on thefinish or if the decora‐
tive foil is dull: use thePa int Cleaner recom‐
mended and appr ovedfo r Mercedes-Benz. R
Insect remains: soak with insect remo ver and
ri nse off the treated areas af terw ards.
R Bird droppings: soak with water and rinse off
af te rw ards.
R Topreve ntwate rst ains, dry a foil-wrapped
ve hicle with a soft, absorbent clo thafter
eve rycar wash.
Av oiding dama getothe decorative foil
R The service life and colouring of decorative
fo ils are impaired by:
- sunlight
- temp erature, e.g. hot air blo wer
- weather conditions
- stone chippings and dirt
- chemical cleaning agents
- oily products
R Do not use polish on matt decorative foil.
Po lishing will ha vethe ef fect of shining the
fo il-wrapped sur face.
R Do not treat matt or stru ctured deco rative
fo ils with wax.Pe rm anent stains may occur. Main
tenance and care 365

All
vehicles
+ ENVIRONMENTAL
NOTEEnvironmental
dama gedue toimproper disposal of bat‐
te ries Batteries conta
in pollutants. It is
illegal todispose of them with the household
ru bbish. #
Dispose of batteries in an
environmen tally responsible manner.
Ta ke dischar ged batteries toaqu alified
specialist workshop or toa collection
point for used batteries. If
yo u ha vetodisconnect the12 V batter y,con‐
ta ct a qualified specialist workshop.
Comply with saf ety no tes and take protective
measures when handling batteries. Risk of
explosion. Fire, naked
flames and smoking are
prohibi ted when handling the batter y.
Av oid creating spar ks. Electrolyte
or battery acid is cor ro‐
sive. Avoid contact with the skin, eyes
or clo thing. Wear suitable pr otective
clo thing, in particular glove s, an
apron and a face mas k.Immedia tely
ri nse electrolyte or acid splashes off
with clean water.Consult a doc tor if
necessar y. We
ar saf etygl asses. Ke
ep children away. Obser
vethis Owner's Manual.
Obser vethefo llowing if you do not intend touse
th eve hicle over an extended pe riod of time:
R Activate standby mode.
R Alternatively: connect the battery toa bat‐
te ry charge r appro vedby Mercedes-Benz or
consult a qualified specialist workshop to
disconnect the batter y. Note
s onstarting assi stance and charging
th e12 V battery Ve
hicles with a lithium-ion battery
When charging the battery and during starting
assis tance, al ways use the jump-s tart connec‐
tion point in the engine compartment. 382
Breakdown assis tance

*
NO
TEDama getothe battery from over‐
vo ltage When
charging using a bat tery charge r with‐
out a restriction of the maximum charging
vo ltage, the battery or the on-board electron‐
ics can be damaged. #
Only use battery charge rs with a maxi‐
mum charging voltage of 14.8 V. All
other vehicles
When charging the battery and during starting
assis tance, al ways use the jump-s tart connec‐
tion point in the engine compartment.
* NO
TEDama getothe battery from over‐
vo ltage When
charging using a bat tery charge r with‐
out a restriction of the maximum charging
vo ltage, the battery or the on-board electron‐
ics can be damaged. #
Only use battery charge rs with a maxi‐
mum charging voltage of 14.8 V. &
WARNING Risk ofexplosion from hydro‐
ge nga s igniting
There is a danger of hydrogen gas igniting
when charging the battery if there is a short
circuit or spar ksstart toform. #
Make sure that the positive term inal of
th e connected battery does not come
into conta ct withvehicle parts. #
Never place me tal objects or tools on a
batter y. #
The described order of the battery
clamps must be obser ved when con‐
necting and disconnecting the batter y. #
When giving starting assis tance, al ways
make sure that you on lyconnect bat‐
te ry term inals with identical polarity. #
During starting assis tance, you must
obse rveth e described order for con‐
necting and disconnecting the jump
lead. #
Do not connect or disconnect the bat‐
te ry cla mp s while the engine is running. &
WARNING Risk ofexplosion during
ch arging process and starting assis tance
During thech arging process and starting
assis tance, the battery may release an explo‐
sive gas mixture. #
Avoid fire , naked flames, creating
spar ksand smoking. #
Make sure there is suf ficient ventila‐
tion. #
Do not lean over a batter y. &
WARNING Risk ofexplosion from a fro‐
zen battery
A dischar ged battery may freeze at temp era‐
tures slightly abo veor below freezing point.
During starting assis tance or battery charg‐
ing, bat tery gas can be released. #
Alw ays allow a battery tothaw before
ch arging it or per form ing starting assis‐
ta nce. Breakdown assi
stance 383

If
th e indicator/warning lamps in the instrument
clus ter do not light up at low temp eratures, it is
ve ry likely that the dischar ged battery has fro‐
zen. In this case you may neither jump-s tart the
ve hicle nor charge the batter y.
The service life of a battery that has been
th awe d may be dramatically shor tened. The
st arting characteristics may be impaired, espe‐
cially at low temp eratures.
It is recommended that you ha veathaw ed bat‐
te ry checked at a qualified specialist workshop.
All vehicles
* NO
TEDama gecaused bynumerous or
ex tended attem ptsto start the engine Nume
rous or extended attem ptsto start the
engine may damage the catalytic con verter
due tonon-combu sted fuel. #
Avoid numerous and extended attem pts
to start the engine. Obser
vethefo llowing points during starting
assis tance and when charging the battery:
R Only use undamaged jump lead/charging
cables with a suf ficient cross-section and
insula tedte rm inal clamps.
R Non- insulated parts of thete rm inal clamps
must not come into con tact wi thother me tal
parts while the jump lead/charging cable is
connected tothe battery/jump-s tart connec‐
tion point.
R The jump lead/charging cable must not
come into contact wi thany parts which may
mo vewhen the engine is running.
R Alw ays make sure that nei ther you nor the
battery is elect rostatically charge d.
R Keep away from fire and naked flames.
R Do not lean overth e batter y.
Obser vethe additional following points when
ch arging the battery:
R Only use battery charge rs tested and
appr oved for Mercedes-Benz.
R Read the battery charge r's operating instruc‐
tions before charging the batter y. Obser
vethe additional following points during
st arting assis tance:
R Starting assis tance may only be pr ovided
using vehicles, batteries or other jump start
devices with a nominal voltage of 12V.
R The vehicles must not touch.
R Vehicles with a petrol engine: jump-start
th eve hicle only when the engine and exhaust
sy stem are cold. St
arting assi stance and charging the12 V
battery Preparing
starting assi stance/charging #
Secure theve hicle byapplying the electric
parking brake. #
Automatic transmission: shiftthe trans‐
mission toposition j. #
Manual transmission: shiftthe transmis‐
sion toneutral. #
Switch off the ignition and all electrical con‐
sumers. #
Open the bonn et. 384
Breakdown assis tance

#
Fold co ver1 up in the direction of the
ar row. #
Slide co ver2 of positive clamp 3onthe
jump-s tarting connection point in the direc‐
tion of the ar row.
St arting assi stance #
Connect positive contact 3onyour vehicle
to the positive term inal of the donor battery
using the jump lead. Alw ays begin with posi‐
tive clamp 3onyour ow nve hicle firs t. #
Start the engine of the donor vehicle and run
it at idling speed. #
Connect the negative term inal of the donor
battery toear thpoint 4ofyour vehicle
using the jump lead. Begin with the donor
battery firs t. #
Start the engine of your ow nve hicle. #
Let the engines runfo r se veral minutes. #
Before disconnecting the jump leads, switch
on an electrical consumer in your ow nve hi‐
cle, e.g. there ar wind owheater or the light‐
ing.
When thest arting assis tance procedu reis com‐
ple te: #
First,re mo vethe jump leads from ear thpoint
4 and the negative term inal of the donor
batter y,then from positive conta ct3 and
th e positive term inal of the donor batter y.
Begin ea chtime wi th the conta cts onyour
ow nve hicle firs t. #
Afterre moving the jump leads, close co ver
2 of positive contact 3. #
Close co ver1. Breakdown assi
stance 385

To
avo id damage totheve hicle, deactivate
th ese sy stems in thefo llowing or similar sit‐
uations: #
During towing #
In a car wash Mercedes-Benz
recommends transporting your
ve hicle in the case of a breakdown, rath er than
to wing it away.
Fo rto wing, use a tow rope or tow bar with bo th
axles on the ground. Do not use tow bar sys‐
te ms.
* NO
TEDama getotheve hicle due to tow‐
ing away incor rectly #
Obser vethe instructions and no tes on
to wing away. Ve
hicles with manual transmission Pe
rm itted towing me thods
Bo th axles on
th e ground Ye
s, maximum 50 km at
50 km/h
Fr ont axle
ra ised Ye
s, maximum 50 km at
50 km/h
Re ar axle
ra ised Ye
s, maximum 50 km at
50 km/h Ve
hicles with automatic transmission Pe
rm itted towing me thods
Bo th axles on
th e ground Ye
s, maximum 50 km at
50 km/h
Fr ont axle
ra ised No
Re ar axle
ra ised Ye
s, if thesteering wheel is
fi xe d in the cent reposition
with a steering wheel lock 4MATIC
vehicles Pe
rm itted towing me thods
Bo th axles on
th e ground Ye
s, maximum 50 km at
50 km/h
Fr ont axle
ra ised No
Re ar axle
ra ised No To
wing with a raised axle: towing should be
per form ed byato wing compan y. To
wing theve hicle with bo thaxles on the
gr ound #
Obser vethe no tes on the permitted towing
me thods (/ page 386). #
Make sure that the battery is connected and
ch arge d.
Obser vethefo llowing points when the battery is
dischar ged:
R the engine cann otbe star ted Breakdown assis
tance 387

#
Screw intheto wing eyeclockwise as far as it
will go and tighten.
Ve hicles with a trailer hitch: vehicles with a
trailer hitch do not ha veare ar brac ketfo rthe
to wing eye. Fasten theto w bar tothe trailer
hitch. #
Make sure that co ver1 engages in the
bumper when youre mo vetheto wing eye.
* NO
TEDama getotheve hicle due to
incor rect use of theto wing eye When a
towing eye is used toreco ver a vehi‐
cle, theve hicle may be damaged in the proc‐
ess. #
Only use theto wing eyeto to waw ay or
to w start theve hicle. *
NO
TEDama getotheve hicle due to
incor rect use of theto wing eye or trailer
hitch When a
towing eye or trailer hitch is used to
re co ver a vehicle, theve hicle may be dam‐
aged in the process. #
Do not use theto wing eye or trailer
hitch to towtheve hicle during reco very. To
w starting theve hicle (eme rgency engine
st art) Ve
hicles with automatic transmission
* NO
TEDama getothe automatic trans‐
mission due to tow-starting The automatic transmission may be damaged
in the process of tow- starting vehicles with
automatic transmission. #
Vehicles with automatic transmission
must not be tow- star ted. #
Vehicles with automatic transmission must
not be tow- star ted. Electrical fuses
Note
s on electrical fuses &
WARNING Risk of accident and inju ry
due to ov erloaded lines
If yo u manipulate or bridge a faulty fuse or if
yo ure place it with a fuse with a higher
amperage, the electric line could be overloa‐
ded.
This could result in a fire. #
Alw aysre place faulty fuses with speci‐
fi ed new fuses conta iningthe cor rect
amperage. *
NO
TEDama gedue toincor rect fuses Electrical components or sy
stems may be
damaged byincor rect fuses, or their func‐
tionality may be significant lyimpaired. Breakdown assis
tance 391

#
Only use fuses that ha vebeen appr oved
by Mercedes-Benz and which ha vethe
cor rect fuse rating. Blown fuses mu
stbe replaced with fuses of the
same rating, which you can recognise bythe col‐
our and the label. The fuse ratings and fu rther
information tobe obser ved can be found in the
fuse assignment diagram.
Fu se assignment diag ram: onthe fuse box in
th e boot (/ page 394).
* NO
TEDama geor malfunctions caused
by moisture Moisture may cause dama
getothe electrical
sy stem or cause it tomalfunction. #
When the fuse box is open, make sure
th at no moisture can enter the fuse
box. #
When closing the fuse box, make sure
th at the seal of the lid is positioned cor‐
re ctly on the fuse box. If
th e newly inser ted fuse also blo ws, ha vethe
cause traced and rectified at a qualified special‐
ist workshop.
Ensure thefo llowing before replacing a fuse:
R The vehicle is secured against rolling away.
R All electrical consumers are switched off.
R The ignition is switched off.
The electrical fuses are located in various fuse
bo xes:
R Fuse box in the engine compartment on the
driver's side (/ page 392)
R Fuse box on the driver's side of the cockpit
(/ page 393)
R Fuse box in the front passenger foot we ll
(/ page 394)
R Fuse box in the boot on theright-hand side
of theve hicle, when vie wed in the direction
of tr avel (/ page 394) Opening and closing
the fuse box in the
engine compa rtment Re
quirements:
R A dry clo thand a sc rewdriver are available.
Obse rveth e no tes on electrical fuses
(/ page 391).
Opening &
WARNING Risk of inju ryfrom using the
windscreen wipers while the engine bon‐
net is open
When the engine bonn etis open, and the
windscreen wipers are set in motion, you can
be trapped bythe wiper linkage. #
Alw ays switch off the windscreen wip‐
ers and ignition before opening the
engine bonn et. 392
Breakdown assis tance

The
tool bag contains:
R Jack
R Gloves
R Wheel wrench
R Centring pin
R Folding chock
R Ratchet for jack Preparing
theve hicle for a wheel change Requ
irements:
R The requ ired tyre-change tool kit is available.
If yo ur vehicle is not equipped with the tyre- ch
ange tool kit, consult a qualified specialist
wo rkshop tofind out about suitable tools.
R The vehicle is not on a slope.
R The vehicle is on solid, non-slippery and le vel
ground. #
Apply the electric parking brake manually. #
Movethe front wheels tothest ra ight-ahead
position. #
Vehicles with automatic transmission:
shift toposition j. #
Vehicles with le vel control sy stem: setthe
normal vehicle le vel (/ page 202). #
Swit choff the engine. #
Make sure that the engine cann otbe star ted. #
Place choc ks orother suitable items under
th e front and rear of the wheel that is diago‐
nally opposite the wheel you wish tochange. #
If necessar y,remo vethe wheel trim/hub
caps (/ page 405). #
Raise theve hicle (/ page 406). Re
moving and fitting the wheel trim/hub
caps Re
quirements:
R The vehicle is prepared for a wheel change
(/ page 405).
Pla stic hub cap #
Toremo ve:turn the cent recover of the hub
cap anti-clockwise and remo vethe hub cap. #
Tofit: make sure that the cent recover of the
hub cap is turned anti-clockwise. #
Position the hub cap and turn the cent re
co ver clockwise until the hub cap engages
ph ysically and audibly. Wheels and tyres
405