2008 MERCEDES-BENZ C300 4MATIC engine

318 Operation
Driving instructions
For more information on winter driving, see
“Winter driving” (
page 360).
Standing waterPassenger compartment
Driving abroad
Abroad, there is an extensive
Mercedes-Benz service network at your
disposal. If you plan to drive into areas
which are not listed in the index of your
Mercedes-Benz Center directory, you
should request pertinent information from
an authorized Mercedes-Benz Center.
Warning!G
If the vehicle becomes stuck in snow, make
sure that snow is kept clear of the exhaust
pipe and from around the vehicle while the
engine is running. Otherwise, deadly carbon
monoxide (CO) gases may enter vehicle in-
terior resulting in unconsciousness and
death.
To assure sufficient fresh air ventilation,
open a window slightly on the side of the ve-
hicle not facing the wind.
Warning!G
The outside temperature indicator is not de-
signed to serve as an ice-warning device and
is therefore unsuitable for that purpose. In-
dicated temperatures just above the freez-
ing point do not guarantee that the road
surface is free of ice.
!Do not drive through flooded areas or water
of unknown depth. Before driving through water,
determine its depth. Never accelerate before
driving into water. The bow wave could force wa-
ter into the engine and auxiliary equipment, thus
damaging them.
If you must drive through standing water, drive
slowly to prevent water from entering the pas-
senger compartment or the engine compart-
ment. Water in these areas could cause damage
to electrical components or wiring of the engine
or transmission, or could result in water being in-
gested by the engine through the air intake caus-
ing severe internal engine damage. Any such
damage is not covered by the Mercedes-Benz
Limited Warranty.
Warning!G
Always fasten items being carried as secure-
ly as possible.
In an accident, during hard braking or sud-
den maneuvers, loose items will be thrown
around inside the vehicle, and cause injury
to vehicle occupants unless the items are
securely fastened in the vehicle.
The trunk is the preferred place to carry
objects.

319 Operation
Driving instructions
Control and operation of radio
transmitters
COMAND*, radio, and telephone*Telephones and two-way radios
Radio transmitters, such as a portable tele-
phone or a citizens band unit should only
be used inside the vehicle if they are con-
nected to an antenna that is installed on
the outside of the vehicle.
Refer to the radio transmitter operation in-
structions regarding use of an external an-
tenna.
Catalytic converter
Your Mercedes-Benz is equipped with
monolithic-type catalytic converters, an
important element in conjunction with the
oxygen sensors to achieve substantial con-
trol of the pollutants in the exhaust emis-
sions. Keep your vehicle in proper
operating condition by following our rec-
ommended maintenance instructions as
outlined in your Maintenance Booklet.
Warning!G
Please do not forget that your primary re-
sponsibility is to drive the vehicle safely.
Only operate the COMAND (Cockpit Man-
agement and Data System), radio, or tele-
phone
1 if road, weather and traffic
conditions permit. Otherwise, you may not
be able to observe traffic conditions and
could endanger yourself and others.
Bear in mind that at a speed of just 30 mph
(approximately 50 km/h), your vehicle is
covering a distance of 44 feet (approximate-
ly 14 m) every second.
1Observe all legal requirements.
Warning!G
Never operate radio transmitters equipped
with a built-in or attached antenna (i.e. with-
out being connected to an external antenna)
from inside the vehicle while the engine is
running. Doing so could lead to a malfunc-
tion of the vehicle’s electronic system, pos-
sibly resulting in an accident and/or
personal injury.
!To prevent damage to the catalytic convert-
ers, only use premium unleaded gasoline in this
vehicle.
Any noticeable irregularities in engine operation
should be repaired promptly. Otherwise, exces-
sive unburned fuel may reach the catalytic con-
verter, causing it to overheat and potentially
start a fire.

320 Operation
Driving instructions
Emission control
Certain systems of the engine and the
emission control system serve to keep the
toxic components of the exhaust gases
within permissible limits required by law.
These systems will function properly only
when maintained strictly according to fac-
tory specifications. Any adjustments on
the engine should, therefore, be carried
out only by qualified Mercedes-Benz Cen-
ter authorized technicians.
Engine adjustments should not be altered
in any way. The specified service proce-
dures must be carried out regularly accord-
ing to Mercedes-Benz servicing
requirements. For details please refer to
the Maintenance Booklet.
Warning!G
As with any vehicle, do not idle, park or op-
erate this vehicle in areas where combusti-
ble materials such as grass, hay or leaves
can come into contact with the hot exhaust
system, as these materials could be ignited
and cause a vehicle fire.
Warning!G
Inhalation of exhaust gas is hazardous to
your health. All exhaust gas contains carbon
monoxide (CO), and inhaling it can cause un-
consciousness and possible death.
Do not run the engine in confined areas
(such as a garage) which are not properly
ventilated. If you think that exhaust gas
fumes are entering the vehicle while driving,
have the cause determined and corrected
immediately. If you must drive under these
conditions, drive only with at least one win-
dow fully open at all times.

321 Operation
Driving instructions
Coolant temperature
During severe operating conditions,
e.g. stop-and-go traffic, the coolant tem-
perature may rise to approximately 248°F
(120°C).
The engine should not be operated with
the coolant temperature over 248°F
(120°C). Doing so may cause serious en-
gine damage which is not covered by the
Mercedes-Benz Limited Warranty.
Warning!G

Driving when your engine is badly over-
heated can cause some fluids, which
may have leaked into the engine com-
partment, to catch fire. You could be se-
riously burned.

Steam from an overheated engine can
cause serious burns and can occur just
by opening the hood. Stay away from
the engine if you see or hear steam com-
ing from it.
Stop the vehicle in a safe location away from
other traffic. Turn off the engine, get out of
the vehicle and do not stand near the vehicle
until the engine has cooled down.

322 Operation
At the gas station
Refueling
The fuel filler flap is located on the
right-hand side of the vehicle towards the
rear. Locking and unlocking the vehicle
with the SmartKey or the SmartKey with
KEYLESS-GO* (Canada only) automatically
locks and unlocks the fuel filler flap.1To open fuel filler flap
2To insert fuel filler cap
3Holder
Warning!G
Gasoline is highly flammable and poisonous.
It burns violently and can cause serious per-
sonal injury.
Never allow sparks, flame or smoking mate-
rials near gasoline!
Turn off the engine before refueling.
Whenever you are around gasoline, avoid in-
haling fumes and any skin or clothing con-
tact. Extinguish all smoking materials.
Direct skin contact with fuels and the inha-
lation of fuel vapors can damage your
health.
Warning!G
C 300/C 300 4MATIC/C 300 4MATIC Sport
and 300 Sport (with automatic transmis-
sion*):
Flexible Fuel Vehicles (identified by a label
reading Premium gasoline or E85 only! on
fuel filler flap):
Ethanol fuel (E85) and its vapors are highly
flammable, poisonous and burn easily. Etha-
nol fuel can cause serious injuries if ignited
or if you come into contact with it or inhale
fumes of it. Avoid inhalation of ethanol
fumes and skin contact with ethanol. Extin-
guish all open flames before refueling. Never
smoke or create sparks close to ethanol.
iIn case that the central locking system does
not release the fuel filler flap, or the opening
mechanism is clamping, notify Roadside Assis-
tance or an authorized Mercedes-Benz Center.
iOnly use premium unleaded gasoline with a
minimum Posted Octane Rating of 91 (average
of 96 RON / 86 MON). Information on gasoline
quality can normally be found on the fuel pump.
C 300/C 300 4MATIC/C 300 4MATIC Sport and
300 Sport (with automatic transmission*):
Flexible Fuel Vehicles are identified by a label
reading Premium gasoline or E85 only! on the
fuel filler flap.

323 Operation
At the gas station
Turn off the engine.
Vehicles with automatic transmission*:
Move the gear selector lever to
positionP (
page 140).
Remove the SmartKey from the starter
switch.
Vehicles with SmartKey with
KEYLESS-GO*:
Turn off the engine by pressing the
KEYLESS-GO* button once.
Open the driver’s door (this puts
the starter switch in position0,
same as with the SmartKey re-
moved from the starter switch). The
driver’s door then can be closed
again.
Open the fuel filler flap by pushing at
the point indicated by arrow 1.The fuel filler flap springs open.
Turn the fuel cap counterclockwise and
hold on to it until possible pressure is
released.
Take off the fuel filler cap and set it in
the direction of arrow 2 and place it
into holder 4 located on the inside of
the fuel filler flap.
To prevent fuel vapors from escaping
into open air, fully insert filler nozzle
unit.
Only fill your tank until the filler nozzle
unit cuts out – do not top off or over-
fill.
Replace the fuel cap by turning it clock-
wise until it audibly engages.
Close the fuel filler flap.
You should hear the latch close shut.
For more information on gasoline or E85, see
“Premium unleaded gasoline” (
page 481) or
the Factory Approved Service Products
pamphlet (USA only) in your vehicle literature
portfolio, or contact an authorized
Mercedes-Benz Center.
Warning!G
Overfilling of the fuel tank may create pres-
sure in the system which could cause a gas
discharge. This could cause the gas to spray
back out when removing the fuel pump noz-
zle, which could cause personal injury.
iMake sure to close the fuel filler flap before
locking your vehicle as the flap locking pin pre-
vents closing after you have locked the vehicle.
iLeaving the engine running and the fuel cap
open can cause the yellow engine malfunction
indicator lamp ± to illuminate.
For more information, see the “Practical hints”
section (
page 378).

324 Operation
At the gas station
Check regularly and before a long trip
1Coolant level
2Brake fluid
3Windshield washer and headlamp
cleaning system*Windshield washer system and head-
lamp cleaning system*
For more information on refilling the wash-
er reservoir, see “Windshield washer sys-
tem and headlamp cleaning system*”
(
page 330).
Coolant
For more information on coolant, see
“Coolant level” (
page 329) and see “Fu-
els, coolants, lubricants, etc.”
(
page 476).
Brake fluid
For information on brake fluid, see “Brake
fluid” (
page 480).Engine oil level
For more information on engine oil, see
“Engine oil” (
page 327).
Vehicle lighting
Check function and cleanliness. For more
information on replacing light bulbs, see
“Replacing bulbs” (
page 430).
For more information, see “Lighting”
(
page 108).
Tire inflation pressure
For information on tire inflation pressure,
see “Checking tire inflation pressure”
(
page 341).iOpening the hood (page 325).!If you find that the brake fluid in the brake
fluid reservoir has fallen to the minimum mark or
below, have the brake system checked for brake
pad thickness and leaks immediately. Notify an
authorized Mercedes-Benz Center immediately.
Do not add brake fluid as this will not solve the
problem. For more information, see “Practical
hints” (
page 376) and (page 400).

325 Operation
Engine compartment
Engine compartment
Hood
Opening
Warning!G
Do not pull the release lever while the vehi-
cle is in motion. Otherwise the hood could
be forced open by passing air flow.
This could cause the hood to come loose
and injure you and/or others.
Warning!G
If you see flames or smoke coming from the
engine compartment, or if the coolant tem-
perature gauge indicates that the engine is
overheated, do not open the hood. Move
away from vehicle and do not open the hood
until the engine has cooled down. If neces-
sary, call the fire department.
Warning!G
You could be injured when the hood is open
– even when the engine is turned off.
Parts of the engine can become very hot. To
prevent burns, let the engine cool off com-
pletely before touching any components on
the vehicle. Comply with all relevant safety
precautions.
Warning!G
To help prevent personal injury, stay clear of
moving parts when the hood is open and the
engine is running.
The radiator fan may continue to run for ap-
proximately 30 seconds or even restart af-
ter the engine has been turned off. Stay
clear of fan blades.
Warning!G
The engine is equipped with a transistorized
ignition system. Because of the high voltage
it is dangerous to touch any components (ig-
nition coils, spark plug sockets, diagnostic
socket) of the ignition system

with the engine running

while starting the engine

if ignition is “on” and the engine is
cranked manually