coolant temperature MERCEDES-BENZ M-Class 2012 W166 Owner's Manual

norm
aland notasign tha tther eis a
ma lfunctio n. i
The
cooling with aird ehumidification
func tion uses refriger antR134a. This
coolant doesnotcontain
chlorof luorocarbon s,and therefore does
not damage theozon elayer.
Activating/d eactivating X
To activa te:press the¿/Á button.
The indicat orlamp inthe ¿/Á
button lightsup.
X To deactiva te:press the¿/Á
button .
The indicat orlamp inthe ¿/Á
button goesout.Thecooling withair
dehumidification function hasadelayed
switch -offfeature.
Problems withthecooling withair
dehum idificat ionfunction When
youpress the¿/Á button,the
indicat orlamp inthe button flashes three
times orremains off.You cannolonger switch
on the cooling withairdehumidification
func tion.
X Consult aqualified specialist workshop. Sett
ingclimat econtrol toaut omat ic G
WARN
ING If
you switch offthe cooling function,the
vehicle willnotbecooled whenweather
con ditions arewarm. Thewindows canfogup
more quickly. Window foggingmayimpair
visibility andendanger youand other s.
In automatic mode,thesettemper atureis
maint ained automatic allyatacon stan tlevel.
The system automatic allyregulates the
temper atureofthe dispensed air,the airflow
and theairdistribut ion.
Autom aticmode willachieve optimal
operation ifcooling withairdehumidification is
also activat ed.Ifdesired, coolingwithair
dehumidification canbedeactivat ed.
In the rear compart ment,you can also switch
climate control forthe rear seats toautomatic
mode usingtheà button .
X Turn theSmart Keytoposition 2in the
ignition lock.
X Set thedesired temperature.
X To activa te:press theà button .
The indicat orlamp inthe à button lights
up. Autom aticairdistribut ionand airflow
are activ ated. i
Autom
aticclimate control: when
automatic modeisactivat ed,you can
select aclimate modesetting
(Y page 129).
X To switch off:press the_ button .
or
X Press theI orK button .
The indicat orlamp inthe à button goes
out. Adju
sting theclimat emode settings
(AIR FLOW)
This function isonly available withautomatic
climate control.
The climate control settings areespecially
effec tiveathigh temper atures.
You canselect thefollowing climatecontrol
sett ings inautomatic mode:
FOCUS highairflow thatisset slightly
cooler
MED IUM medium airflow,standard setting
DIF FUS Elow airflow thatisset slightly
warmer andwith alower rateof
airflow Opera
tingtheclimate controlsystem
129Climate control Z

X
To dea ctivate :pre ssthe Ì/Á
bu tton.
The indicator lamp inthe Ì/Á
bu tton goesou t. i Re
sidu alhea tisdeactivated
automaticall y:
R after about30 minutes
R when theignition isswitched on
R ifthe battery voltage drops
R ifthe coolant temperature istoo low Setting
theairvents Importa
ntsafety notes G
WARNING When
operating theclimate control,the air
that enters thepassenger compartment
through theairvents canbevery hotorvery
cold (depending onthe settemperature). This
could cause burnsorfrostbite tounprotected
skin inthe immediate areaofthe airvents.
Always keepsufficient distancebetween
unprotected partsofthe body andtheair
vents. Ifnecessary, usetheairdistribution
adjustment todirect theairtoair vents inthe
vehicle interior thatarenot inthe immediate
area ofunprotected skin.
In order toensure thedirect flowoffresh air
through theairvents intothevehicle interior,
please observe thefollowi ngnotes:
R keep theairinlet grille onthe hood andin
the engine compartment onthe front -
passenger sidefreeofblockages, suchas
ice, snow orleaves.
R never covertheairvents orair intake grills
in the vehicle interior. i
For
virtually draft-free ventilation, adjust
the sliders ofthe airvents tothe cent er
position. Setting
thecenter airvents :
Center airvent, left
; Center airvent, right
= Center ventthumbwheel, right
? Center ventthumbwheel, left
X To open/c lose:turnthumbwheels =
and ?tothe right orleft. Setting
theside airvents X
To open/c lose:turn thumbwheel =upor
down. Setting
theglove boxairvent
When automatic climatecontrolisactivated,
the glove boxcanbecooled, forinstance to
cool itscont ents. Thelevel ofairflow depends
on the airflow andairdistribution settings.
At high outside temperatures, opentheair
vent andactivate the"cooling withair
dehumid ification" function. 134
Setting
theairventsClimate control

Problems
withtheengine Problem Possible
causes/co nsequences andM Solutions
The
engine doesnot
start. Thestarter motor
can beheard. R
There isamalfunction inthe engine electron ics.
R There isamalfunction inthe fuel supply .
X Try tostart theengine again(Ypage 140). Avoid excessively
long andfrequent attemptsto start theengine asthese willdrain
the battery.
If the engine doesnotstart after several attempt s:
X Consult aqual ified specialist workshop, e.g.anauthorized
Mercedes-B enzCenter. The
engine doesnot
start. Youcannot hear
the starter motor. The
on-board voltageistoo low because thebattery istoo weak
or discharged.
X Jump-start thevehicle (Ypage 341).
If the engine doesnotstart despite attemptsto jump-st artit:
X Consult aqual ified specialist workshop, e.g.anauthorized
Mercedes-B enzCenter. The
starter motorwasexposed toathermal loadthatwastoohigh.
X Allow thestarter motortocool down forapproximately two
minutes.
X Try tostart theengine again.
If the engine stilldoes notstart:
X Consult aqual ified specialist workshop, e.g.anauthorized
Mercedes-B enzCenter. The
engine isnot
running smoothly and
is misfiring. There
isamalfunction inthe engine electron icsoramechanical
componen tof the engine management system.
X Only depress theaccelerator pedalslightly.
X Have thecause rectifiedimmediately ataqual ified specialist
workshop, e.g.anauthorized Mercedes-B enzCenter.
Otherwise, non-combusted fuelmay getinto thecatalytic
conv erter anddamage it. The
coolant
temperature gauge
shows avalue above
248 ‡(120 †). The
coolant levelistoo low. Thecoolant istoo hotand theengine
is no longer beingcooled sufficiently.
X Stop assoon aspossible andallow theengine andthecoolant
to cool down.
X Check thecoolant level(Ypage 315). Observe thewarning
notes asyou dosoand add coolant ifnecessary. Driving
143Driving and parking Z

Useful
information
i This
Operat or'sManual describesall
models andallstan dard andoption al
equipment ofyour vehicle available atthe
time ofpublication ofthe Operat or's
Manual. Country-specificdiffer encesare
possible. Pleasenotethat your vehicle may
not beequipped withallfeature s
descr ibed. Thisalso applies tosafet y-
related systemsand func tions. i
Please
readtheinfor mation onqualified
specialist workshops(Ypage 25). Impor
tant safet ynotes You
willfind anillustrat ionofthe instrumen t
clust erinthe "Ataglance" section
(Y page 29). G
WARN
ING A
driver' satt ent ion tothe road andtraffic
con dition smust always behis/her primary
focus whendriving.
For your safetyand thesafet yof other s,
select ingfeature sthr ough themultifun ction
steer ingwheel should onlybedone bythe
driver whentrafficand road condition spermit
it to be done safely.
Bear inmind thatataspeed ofjust 30mph
(approxim ately50km/ h),your vehic leis
cove ringadistan ceof44 feet (approxim ately
14 m)every second. G
WARN
ING No
messages willbedisplayed ifeither the
inst rumen tclust eror the multif unction
display isinoper ative.
As aresult, youwillnotbeable tosee
info rmat ionabout yourdrivin gcon dition s,
such as
R speed
R outside temperatur e
R warnin g/indicato rlamps R
malf unction/ warn ingmes sages
R failur eof any systems
Dr ivin gch arac terist ics may beimpair ed.
If you must continue todriv e,do sowith added
caut ion.Contac tana uth oriz edMer cedes-
Ben zCent eras soon aspossible. G
WARN
ING Malfunct
ionand warning messages areonly
indicat edfor cert ainsystems andare
inten tionally notvery detailed. The
malfunct ionand warning messages are
simply areminder withrespect tothe
operation ofcert ainsystems. Theydonot
replace theowner's and/ordriver's
respons ibilitytomaint ainthe vehicle's
operatin gsafety. Haveallrequired
maint enanc eand safety checksperform edon
the vehicle. Bringthe vehicle toan authorized
Mercedes- BenzCenter toaddress the
malfunct ionand warning messages. Displays
andopera tion Coolant
temperaturedispla y G
WARN
ING Drivin
gwhen yourengine isoverheat edcan
cause somefluidswhich mayhave leaked into
the engine compart menttocatc hfire. You
could beseriously burned.
St eam from anoverheat edengine cancause
serious burnswhich canoccur justbyopening
the engine hood.Stay away fromtheengine
if you seeorhear steam comingfrom it.
St op the vehicle inasafe location awayfrom
other traffic.Turn offthe engine, getout ofthe
vehicle anddonot stand nearthevehicle until
the engine hascooled down.
The coolant temperaturegauge isin the
inst rument clusteronthe right- hand side.
Under normaloperatin gcon ditions andwith
the specified coolantlevel,thecoolant
temper aturemayriseto248 ‡(120 †). 222
Displays
andopera tionOn-board computer and displays

!
Ifthe coolant temperature istoo high a
displa ymessage isshown.
If the coolant temperature risesabove
248 ‡(120 †),donot drive anyfurther as
this could damage theengine. Tachometer
The redband inthe tachometer indicatesthe
engine's overrevving range.
! Donot drive inthe overrevving range,as
this could damage theengine.
The fuel suppl yis interrupted toprotect the
engine whenthered band isreached. Outside
tempera turedisplay
The outside temperature displayis in the
multifunction display(Y page 224). G
WARNING The
outside temperature indicatorisnot
designed toserve asan ice-warning device
and istherefore unsuitablefor that purpose.
Indicated temperatures justabove the
freezing pointdonot guara nteethattheroad
surface isfree ofice. The road maystillbeicy,
especial lyin wooded areasoron bridges.
Changes inthe outside temperature are
displa yedafter ashort delay. Speedometer
withsegments
The segments inthe speedometer indicate
which speed rangeisavail able.
Cruise control(Ypage 167)activated:
The segments lightupfrom thestored speed
to the maximum speed.
DISTRONIC PLUS(Ypage 169)activated:
One ortwo segments inthe setspeed range
light up.
DISTRONIC PLUSdetects avehicle infront :The
segments betweenthespeed ofthe
vehicle infront andthestored speedlightup. Operating
theon-board computer
Overview The
on-board computer isactivated assoon
as you turn theSmartKey toposition 1in the
ignition lock.
You cancont rolthe multifunction displayand
the settings inthe on-board computer using
the buttons onthe multifunction steering
wheel. :
Multifunction display
; Toswitch onthe Voice Control System;
see theseparate operating instructions
= Right controlpanel
? Left controlpanel
A Back button Dis
plays andoperation
223On-board computer and displays Z

Disp
laymessa ges Poss
iblecauses/c onseq uences and M Solu
tions ?
Coo
lantLev elLow Sto
pVeh icl eTur n Eng
ine Off The
coolan tistoo hot.
X Pull over andstop thevehicle safelyandswitch offthe engine,
pay ing attent iontoroad andtraffic conditions.
X Make surethattheairsuppl yto the engine radiatorisnot
blocked, e.g.bysnow, slushorice.
X Wait untilthedispla ymessage disappearsbefore restarting the
engine. Otherwise, thereisarisk ofengine damage .
X Pay attent iontothe coolant temperature display.
X Ifthe temperature increasesagain,visit aqual ified speciali st
workshop immediately . The
poly-V-belt mayhave torn.
X Pull over andstop thevehicle safelyandswitch offthe engine,
pay ing attent iontoroad andtraffic conditions.
X Open thehood.
X Check whether thepoly-V-belt istorn.
If the poly-V-belt istorn:
! Donot cont inue driving. Theengine couldotherwise overheat.
X Consult aqual ified speciali stworkshop.
If the poly-V-belt isnot dam aged:
X Wait untilthedispla ymessage disappearsbefore restarting the
engine. Otherwise, thereisarisk ofengine damage .
X Pay attent iontothe coolant temperature display.
X Visit aqual ified speciali stworkshop. G
WARNING Driving
whenyourengine isoverheated cancause somefluidswhich mayhave leaked intothe
engine compartment tocatch fire.Youcould beseriously burned.
Steam fromanoverheated enginecancause serious burnswhich canoccur justbyopening the
engine hood.Stayawayfrom theengine ifyou seeorhear steam coming fromit.
Stop thevehicle inasafe location awayfrom other traffic. Turnoffthe engine, getout ofthe
vehicle anddonot stand nearthevehicle untiltheengine hascooled down.
! Ifthe coolant temperature exceeds248‡(120 †)donot cont inue driving. Theengine will
otherwise bedamage d. Dis
play messages
255On-board computer and displays Z

Problem Possible
causes/co nsequences andM Solutions
8
The
yello wreserve fuel
warning lamplights up
while theengine is
running. The
fuel level hasdropped intothereserve range.
X Refuel atthe nearest gasstation. ?
The
redcoolant
warning lamplights up
while theengine is
running andthecoolant
temperature gaugeis
at the start ofthe scale. The
temperature sensorforthe coolant temperature gaugeis
defective.
The coolant temperature isno longer beingmonitor ed.There isa
risk ofengine damage ifthe coolant temperature istoo high.
X Pull over andstop thevehicle safelyandswitch offthe engine,
payi ngatten tiontoroad andtraffic condition s.Do not cont inue
driving underanycircumst ances.
X Apply theelectric parking brake.
X Consult aqual ified specialist workshop. War
ning andindicator lampsin the instrum entcluster
277On-board computer and displays Z

Problem Possible
causes/co nsequences andM Solutions
?
The
redcoolant
warning lampcomes on
while theengine is
running. The
coolant levelistoo low.
If the coolant leveliscorrec t,the airflow tothe engine radiator
may beblocked orthe electric engineradiator fanmay be
malfunction ing.
The coolant istoo hotand theengine isno longer beingcooled
sufficiently.
X Observe theadditional displaymessages inthe multifunct ion
display .
X Pull over andstop thevehicle safelyandswitch offthe engine,
payi ngatten tiontoroad andtraffic condition s.
X Allow theengine andcoolant tocool.
X Check thecoolant levelandadd coolant (Ypage 315). Observe
the warning notes.
X Ifyou need toadd coolant moreoften thanusual,have the
engine coolant systemchecked.
X Make surethattheairsupply tothe engine radiator isnot
blocked, e.g.bysnow, slushorice.
X At coolant temperatures under248‡(120 †),drive tothe next
qualified specialist workshop.
X Avo idsubjec tingthe engin etoheavy loads, e.g.driving in
mountainous terrain,andstop- and-go traffic. ?
The
redcoolant
warning lampcomes on
while theengine is
runnin g.Awarning tone
also sounds. The
coolant temperat urehas exceeded 248‡(120 †).The
airflow tothe engine radiator maybeblocked orthe coolant level
may betoo low.
The engine isnot being cooled sufficient lyand may bedamaged.
X Observe theadditional displaymessages inthe multifunct ion
display .
X Pull over andstop thevehicle safelyandswitch offthe engine,
paying attentiontoroad andtraffic conditions.
X Allow theengine andcoolant tocool.
X Check thecoolant levelandadd coolant (Ypage 315). Observe
the warning notes.
X Ifyou need toadd coolant moreoften thanusual ,have the
en gin eco olan tsyst em checke d.
X Mak esur eth at theair supp lyto theen gin eradi ator isno t
bloc ked, e.g. by snow, slushor ice .
X At coolan ttemperatures under248‡(120 †),drive tothe next
qualified specialist workshop.
X Avo idsubjec tingthe engin etoheavy loads, e.g.driving in
mountainous terrain,andstop- and-go traffic. 278
War
ning andindicator lampsin the instru mentclusterOn-board computer and displays

G
WARNING Driving
whenyourengi ne isove rheatedcan causesom efluids which mayhave leaked intothe
engin ecom partmen ttocatch fire.Youcould beseriously burned.
Steam fromanoverheated enginecancause serious burnswhich canoccur justbyopening the
engine hood.Stayaway fromtheengine ifyou seeorhear steam coming fromit.
Stop thevehicle inasafe location awayfromother traffic.Turn offthe engine, getout ofthe
vehicle anddonot stand nearthevehicle untiltheengine hascooled down.
! Ifthe coolant temperature exceeds248‡(120 †)donot cont inue driving. Theengine will
otherwise bedamaged. Driving
systems Problem Possible
causes/cons equencesandM Solutions
·
The
reddistance
warning lamplights up
while thevehicle isin
motion .A warning tone
also sounds. G
Risk
ofaccident The
warning isissued ifyou approach astation aryvehicle ora
vehicle drivingaheadofyou attoo high aspeed.
X Be prepared tobrake immediately.
X Pay careful attentiontothe traffic situation. Youmay have to
brake ortake evasive action.
More informat ionabout DISTRONIC PLUS(Ypage 169)and
PRE-S AFE®
Brake (Ypage 65). War
ning andindicator lampsin the instru mentcluster
279On-board computer and displays Z

Furth
erinfor mationonengi neoil
(Y page 388). Che
cking and adding otherserv ice
pr odu cts
Checkin gth ecoolant level On
lyche ckthecoo lant level when theveh icle
is on alevel surface and theeng inehas cooled
down .
X Turn theSm artKey toposit ion
2 (Y page 139)intheign itio nlock .
On veh icleswith KEYLE SS-GO ,pres sth e
St art /S topbutt ontwic e(Ypage 139).
X Check thecoolant temperaturegauge in
the multifun ction display.
The coolant temperaturemustbebelow
158 ‡(70 †). G
WARN
ING In
order toavoid anypoten tiallyserious burns:
R use extreme caution whenopenin gthe
hood ifther eare any signs ofsteam or
coolant leakingfromthecoolin gsystem ,or
if the coolant temperaturedisplay indicates
that thecoolant isoverheat ed.
R do not remov ethe pressure caponthe
coolant reservoirifthe coolant temperature
is above 158‡(70 †). Allow theengine to
cool downbefore removin gthe cap. The
coolant reservoircon tains hotfluid andis
under pressure.
R using arag, slowly turnthecap
approximat ely1
/ 2 turn
torelieve excess
pressure. Ifopened immediately, scalding
hot fluid andsteam willbeblown outunder
pressure.
R do not spill antifreeze onhot engine parts.
An tifr eeze contains ethylene glycolwhich
may burn ifit comes intocontact with hot
engine parts. X
Slowly turncap:half aturn count er-
clock wiseandallow excesspressure to
escape.
X Turn cap:furth ercount er-clockwise and
remove it.
If the coolant isat the level ofmarker bar
= inthe filler neck when cold,there is
enough coolant incoolant expansion
tank ;.
If the coolant isapproximat ely0.6 in
(1.5 cm)above marker bar=inthe filler
neck when warm, thereisenough coolant
in coolant expansion tank;.
X Ifneces sary,addcoolant thathasbeen
test edand approved byMercedes- Benz.
X Replace cap:and turn itclock wiseasfar
as itwill go.
For furth erinfor mation oncoolant ,see
(Y page 389).
Windshield washersystemand
headla mpcleaning system The
washer fluidreservo iris used forboth the
windshield washersystemandtheheadlamp
cleanin gsystem. i
Vehicle
compon entsand their servic e
product smust match.You should,
theref ore,only useproduct sthat have been
test edand approved byMercedes- Benz.
Inf ormation ontest edand approved
product scan beobtained atany authorized
Mercedes- BenzCenter oron the Internet at
htt p://ww w.mbu sa.com (USAonly). Engine
compartment
315Maintenance and care Z