2019 MERCEDES-BENZ C CLASS engine

Rfrequent operation in mountainousterrain oron poorroad surfaces
Rwhenthe engine is often leftidlingfor longperiods
Roperation in particularly dusty conditionsand/or if air-recirculation mode is frequentlyused
Inthese or similar operating conditions, havetheinterior airfilter, engine air cleaner, engine oiland oilfilteretc.changed more frequently. Thetires must bechecked more frequently ifthevehicle is operated under increased loads.Fur‐ther information can be obtained at aqualifiedspecialistworkshop.
Battery disconnection periods
The ASSYST PLUS service interval displaycan only calculatethe service due datewhenthe batteryis connected.
Notedownthe service due date displayed onthe instrument display before disconnectingthe battery (page 351).
Engine compartment
Opening/closingthe hood
\nWARNINGRisk of accident ifthe enginehood is unlatched while driving
An unlocked engine hood may open up whenthevehicle is in motion and blockyour view.
Never unlatchthe engine hood whiledriving.
Beforeevery trip, ensurethattheengine hood is latched.
\nWARNINGRisk of accident and injurywhen opening and closingthe enginehood
When opening or closingthe engine hood, itmay suddenly drop intothe end position.
There is arisk of injuryfor anyone intheengine hood'srange of movement.
Only open or closethe engine hoodwhenthere are no persons intheengine hood'srange of movement.
\nWARNINGDanger of burns when open‐ingthe hood
Ifyou openthe hood whenthe engine hasoverheated or during afireinthe enginecompartment,you could come into contactwith hotgases orother escaping operatingfluids.
Before openingthe hood, allowtheenginetocool down.
Intheevent of afireinthe engine com‐partment,keepthe hood closed andcallthefireservice.
\nWARNINGRisk of injuryduetomovingparts
Certain components inthe engine compart‐ment may continuetomoveor suddenlymoveagaineven afterthe ignition has beenswitched off, e.g.the coolerfan.
Makesure ofthefollowing before performingtasks inthe engine compartment:
Switchthe ignition off.
352Maintenance and care

Nevertouchthe danger zone surround‐ing moving component parts, e.g.therotation area ofthefan.
Removejewelry andwatches.
Keep items of clothing and hairawayfrom moving parts.
\nWARNINGRisk of injuryfromtouchingcomponent parts undervoltage
The ignition system andthe fuel injectionsystemworkunder highvoltage. Ifyoutouchcomponent parts which are undervoltage,you couldreceivean electric shock.
Nevertouch component parts oftheignition system orthe fuel injection sys‐tem whenthe ignition is switched on.
\nWARNINGRisk of burns from hot com‐ponent parts inthe engine compartment
Certain components inthe engine compart‐ment can beveryhot, e.g.the engine,theradiator and parts oftheexhaust system.
Allowthe enginetocool down and onlytouch component parts described inthefollowing.
\nWARNINGRisk of injuryfrom usingthewindshield wipers whilethe engine hoodis open
Whenthe engine hood is open andthe wind‐shield wipers are set in motion,you can betrappedbythe wiper linkage.
Always switch offthe windshield wipersand ignition before openingthe enginehood.
Toopen:pull lever1toreleasethe hood.
Maintenance and care353

Push handle1ofthe hood catch upwardsand liftthe hoodbyapproximately15in(40 cm).Toclose:lowerthe hood and let itfall from aheight of approximately 8 in (20 cm).
Ifthe hood canstill be lifted slightly,openthe hood again and close it with a little moreforce until it engages correctly.
Engine oil
Checkingthe engine oil level usingthe oildipstick
\nWARNINGRisk of burns from hot com‐ponent parts inthe engine compartment
Certain components inthe engine compart‐ment can beveryhot, e.g.the engine,theradiator and parts oftheexhaust system.
Allowthe enginetocool down and onlytouch component parts described inthefollowing.
Requirements:RThe engine must havean oil dipstick.If not,the engine oil level can bechecked only withthe on-board computer (page 355).
Depending onthe engine,the oil dipstick may beinstalled inthe engine compartment in differentlocations.
Thewaiting time beforecheckingthe oil levelwhenthe engine is at normal operatingtempera‐ture isfiveminutes.
Parkthevehicle on a level surface.
Pull oil dipstick1out and wipe off.
Slowly slide oil dipstick1intothe guidetubetothestop, andtakeit out again afterapproximatelythree seconds.ROil level is correct: oil level is between2and3.
ROil leveltoo low: oil level is at3orbelow.
354Maintenance and care

ROil leveltoo high: oil level is above2.
Ifthe oil level istoo low,add1.1 US qt(1 liter) of engine oil.
Ifthe oil level istoo high, drain offexcessengine oil. Consult aqualified specialistworkshop.
Checkingthe engine oil level usingthe on-board computer
RequirementsThe engine must havean oil level sensor. If not,the engine oil level can bechecked only withtheoil dipstick (page 354).
The engine oil level is determined during driving.Determiningthe engine oil level cantakeupto30 minutes with a normal drivingstyle andevenlonger with an active drivingstyle.
In ordertoreceivearesult asquickly as possi‐ble:
RWarmupthe engine
RParkthevehicle on a level surface
RLeavethe enginerunning at idling speed
On-board computer:
ServiceEngine Oil Level
You will see one ofthefollowing messages onthe multifunction display:
RMeasuring Engine Oil Level...: measurementofthe oil level is notyet possible.
Repeattherequest after a maximum of30 minutes driving.
REngine Oil Level OKandthe bar displayforindicatingthe oil level onthe multifunctiondisplay is green and is between "min" and"max":the oil level is correct.
REngine Oil Level Add 1.0 landthe bar displayfor indicatingthe oil level onthe multifunc‐tion display is orange and is below "min":
Add1.1 US qt (1 l) engine oil.
RReduce Engine Oil Levelandthe bar displayfor indicatingthe oil level onthe multifunc‐tion display is orange and is above"max":
Drain offexcess engine oilthat has beenadded. Consult aqualified specialistwork‐shop.
RFor Engine Oil Level Switch Ignition On:
Switch onthe ignitiontocheckthe engine oillevel.
REngine Oil Level System Inoperative: sensorfaulty or not inserted.
Consult aqualified specialistworkshop.
REngine Oil Level System Currently Unavail.:
Closethe hood.
Adding engine oil
\nWARNINGRisk of burns from hot com‐ponent parts inthe engine compartment
Certain components inthe engine compart‐ment can beveryhot, e.g.the engine,theradiator and parts oftheexhaust system.
Allowthe enginetocool down and onlytouch component parts described inthefollowing.
Maintenance and care355

\nWARNINGRisk offireand injury fromengine oil
If engine oil comes into contact withhotcomponent parts inthe engine compart‐ment, it may ignite.
Make surethat no engine oil is spillednexttothefiller opening.
Allowthe enginetocool off andthor‐oughly cleanthe engine oil from compo‐nent parts beforestartingthevehicle.
NOTEEngine damagecausedbyanincorrect oilfilter, incorrect oil or addi‐tives
Do not use engine oils or oilfilterswhich do not correspondtothe specifi‐cationsexplicitly prescribedfortheservice intervals.
Do not alterthe engine oil or oilfilter inordertoachievelongerchange intervalsthan prescribed.
Do not use additives.
Followthe instructions inthe serviceinterval displayregardingthe oilchange.
NOTEDamagecausedbyaddingtoomuch engine oil
Too much engine oil can damagethe engineorthe catalytic converter.
Haveexcess engine oilremoved at aqualified specialistworkshop.
Turncap1counter-clockwise andremoveit.
Add engine oil.
Replace cap1and turn it clockwise asfaras it will go.
Checkthe oil level again (page 354).
356Maintenance and care

Checking coolant level
\nWARNINGRisk of burns from hot com‐ponent parts inthe engine compartment
Certain components inthe engine compart‐ment can beveryhot, e.g.the engine,theradiator and parts oftheexhaust system.
Allowthe enginetocool down and onlytouch component parts described inthefollowing.
\nWARNINGDanger of burns when open‐ingthe hood
Ifyou openthe hood whenthe engine hasoverheated or during afireinthe enginecompartment,you could come into contactwith hotgases orother escaping operatingfluids.
Before openingthe hood, allowtheenginetocool down.
Intheevent of afireinthe engine com‐partment,keepthe hood closed andcallthefireservice.
\nWARNINGRisk of scalding from hotcoolant
The engine cooling system is pressurized,particularly whenthe engine iswarm. Ifyouopenthe cap,you could be scaldedbyhotcoolant spraying out.
Letthe engine cool down before open‐ingthe cap.
When openingthe cap,wear protectivegloves and safetyglasses.
Openthe cap slowlytorelease pres‐sure.
Parkthevehicle on a level surface.
Checkthe coolanttemperature display intheinstrument cluster.The coolanttemperature must be below158 °F (70 °C).
Slowly turn cap1counter-clockwisetorelieve overpressure.
Maintenance and care357

Continue turning cap1counter-clockwiseandremoveit.
The coolant level is correct:
RIfthe engine is cold, uptomarker bar2
RIfthe engine iswarm, upto0.6 in (1.5 cm)over marker bar2
If necessary,add coolantthat has beenapprovedbyMercedes-Benz.RFurther information on coolant(page 429).
Addingwasher fluidtothe windshieldwasher system
\nWARNINGRisk of burns from hot com‐ponent parts inthe engine compartment
Certain components inthe engine compart‐ment can beveryhot, e.g.the engine,theradiator and parts oftheexhaust system.
Allowthe enginetocool down and onlytouch component parts described inthefollowing.
\nWARNINGDanger of burns when open‐ingthe hood
Ifyou openthe hood whenthe engine hasoverheated or during afireinthe enginecompartment,you could come into contactwith hotgases orother escaping operatingfluids.
Before openingthe hood, allowtheenginetocool down.
Intheevent of afireinthe engine com‐partment,keepthe hood closed andcallthefireservice.
\nWARNING‑ Risk offireand injury fromwindshieldwasher concentrate
Windshieldwasher concentrate is highlyflammable. It could ignite if it comes intocontact withhot engine component parts ortheexhaust system.
Make surethat no windshieldwasherconcentrate spills out nexttothefilleropening.
Removecap1bythetab.
Addwasherfluid.
Keepingthe air-water duct free
Keepthe area betweenthe hood andthewindshield free of deposits, e.g. ice, snowand leaves.
358Maintenance and care

Allvehicles
ENVIRONMENTALNOTEEnvironmentaldamagecausedbyimproper disposal ofbatteries
Batteries contain pollutants. It isillegaltodispose ofthem withthe householdrubbish.

Dispose of batteries in anenvironmentallyresponsible manner.Takedischarged batteriestoaqualifiedspecialistworkshop ortoa collectionpointfor used batteries.
Ifyou havetodisconnectthe12V battery,con‐tact aqualified specialistworkshop.
Comply with safety notes andtakeprotectivemeasures when handling batteries.
Risk ofexplosion.
Fire, openflames and smoking areprohibited when handlingthe battery.Avoid creating sparks.
Electrolyteor battery acid is corro‐sive.Avoid contact withthe skin,eyesor clothing.Wear suitable protectiveclothing, in particulargloves, anapron and aface mask.Immediatelyrinse electrolyteor acid splashes offwith cleanwater.Consult a doctor ifnecessary.
Wear safetyglasses.
Keepchildrenaway.
Observethis Operator's Manual.
Observethefollowing ifyou do not intendtousethevehicleover anextended period of time:
RActivatestandby mode.
RAlternatively: connectthe batterytoa bat‐terycharger approvedbyMercedes-Benz orconsult aqualified specialistworkshoptodisconnectthe battery.
Notes onstarting assistance and oncharg‐ingthe12V battery
Vehicles with a lithium-ion batteryWhenchargingthe battery and duringstartingassistance, alwaysusethe jump-startconnec‐tion point inthe engine compartment.
Breakdown assistance377