engine overheat MERCEDES-BENZ C240 2003 W203 Owner's Manual

108 Controls in detailInstrument clusterCoolant temperature display
Turn the SmartKey in the starter switch to
position1 or2.

Call up the trip odometer and main
odometer by pressing button
è

or
ÿ
on the multifunction steering
wheel (page 112).

Press button
j
or
k
until the
coolant temperature display appears.During severe operating conditions and
stop-and-go city traffic, the coolant tem-
perature may rise close to 248°F (120°C).
The engine should not be operated with
the coolant temperature above 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 engine hood. Stay away
from the engine if you see or hear steam
coming from it.
Turn off the engine, get out of the vehicle
and do not stand near the vehicle until it
cools down.
iExcessive coolant temperatures trigger
a warning in the multifunction display.

224 OperationDriving instructionsPower assistanceBrakesTo help prevent brake disk corrosion after
driving on wet road surfaces (particularly
salted roads), it is advisable to brake the
vehicle with considerable force prior to
parking. The heat generated serves to dry
the brakes.
If your brake system is normally only
subject to moderate loads, you should
occasionally test the effectiveness of the
brakes by applying above-normal braking
pressure at higher speeds. This will also
enhance the grip of the brake pads. If the parking brake is released and the
brake warning lamp in the instrument clus-
ter stays on, the brake fluid level in the res-
ervoir is too low.
Brake pad wear or a leak in the system may
be the reason for low brake fluid in the res-
ervoir.
Have the brake system inspected at an au-
thorized Mercedes-Benz Center immedi-
ately.
All checks and service work on the brake
system should be carried out by an autho-
rized Mercedes-Benz Center.
Only install brake pads and brake fluid
recommended by Mercedes-Benz.Warning!
G
When the engine is not running, the brake
and steering systems are without power as-
sistance. Under these circumstances, a
much greater effort is necessary to stop or
steer the vehicleWarning!
G
After driving in heavy rain for some time
without applying the brakes or through wa-
ter deep enough to wet brake components,
the first braking action may be somewhat
reduced and increased pedal pressure may
be necessary to obtain expected braking ef-
fect. Maintain a safe distance from vehicles
in front.
Resting your foot on the brake pedal will
cause excessive and premature wear of the
brake pads.
It can also result in the brakes overheating,
thereby significantly reducing their effec-
tiveness. It may not be possible to stop the
vehicle in sufficient time to avoid an acci-
dent.
!Be very careful not to endanger other
road users when you apply the brakes.
Refer to the description of the Brake
Assist System (BAS) (
page 74).

225 Operation
Driving instructions
After hard braking, it is advisable to drive
on for some time, rather than immediately
parking, so that the air stream will cool
down the brakes faster.
Driving off
Apply the brakes to test them briefly after
driving off. Perform this procedure only
when the road is clear of other traffic.
Warm up the engine smoothly. Do not
place full load on the engine until the oper-
ating temperature has been reached.
When starting off on a slippery surface, do
not allow one drive wheel to spin for an ex-
tended period with the ESP switched off.
Doing so may cause serious damage to the
drive train which is not covered by the
Mercedes-Benz Limited Warranty.
Parking
Warning!
G
If other than recommended brake pads are
installed, or other than recommended brake
fluid is used, the braking properties of the
vehicle can be degraded to an extent that
safe braking is substantially impaired. This
can result in an accident.!When driving down long and steep
grades, relieve the load on the brakes
by shifting into a lower gear to use the
engine’s braking power. This helps pre-
vent overheating of the brakes and re-
duces brake pad wear.
!Simultaneously depressing the
accelerator pedal and applying the
brake reduces engine performance and
causes premature brake and drivetrain
wear.
!Set the parking brake whenever park-
ing or leaving the vehicle. In addition,
move selector lever to positionP (man-
ual transmission: first or reverse gear).
In addition, when parking on hills,
always turn front wheels towards road
curb.

231 Operation
Driving instructions
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 Service Booklet.
Emission control
Certain systems of the engine serve to
keep the toxic components of the exhaust
gases within permissible limits required by
law.
These systems, of course, will function
properly only when maintained strictly ac-
cording to factory specifications. Any ad-
justments on the engine should, therefore,
be carried out only by qualified
Mercedes-Benz Center authorized techni-
cians. Engine adjustments should not be
altered in any way. Moreover, the specified
service jobs must be carried out regularly
according to Mercedes-Benz servicing re-
quirements. For details refer to the Service
Booklet.
!To prevent damage to the catalytic con-
verters, use only premium unleaded
gasoline in this vehicle.
Any noticeable irregularities in engine
operation should be repaired promptly.
Otherwise, excessive unburned fuel
may reach the catalytic converter,
causing it to overheat and start a fire.
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.

232 OperationDriving instructions
Coolant temperature
During severe operating conditions and
stop-and-go city traffic, the coolant tem-
perature may rise close to approx. 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
Inhalation of exhaust gas is hazardous to
your health. All exhaust gas contains carbon
monoxide, and inhaling it can cause uncon-
sciousness and lead to 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.
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 engine hood. Stay away
f r o m t h e e n g i n e i f y o u s e e o r h e a r s t e a m
coming from it.
Turn off the engine, get out of the vehicle
and do not stand near the vehicle until it
cools down.

235 Operation
Engine compartment
Engine compartment
Hood
Opening
1Hood release
Pull lever1 downwards.
The hood is unlocked and handle2 will
extend out of the radiator grill. 2Handle for opening the hood

Pull handle2 to its stop out of radiator
grill.

Pull up on the hood (do not pull up on
the handle) and then release it.
The hood will be automatically held
open at shoulder height by gas-filled
struts.
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.
!To avoid damage to the windshield wip-
ers or hood, never open the hood if the
wiper arms are folded forward away
from the windshield.
Warning!
G
To help prevent personal injury, stay clear of
moving parts when the hood is open and the
engine is running. Make sure the hood is
properly closed before driving. When closing
the hood, use extreme caution not to catch
hands or fingers.
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
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. If necessary,
call the fire department.

239 Operation
Engine compartment
1Coolant expansion tank
Using a rag, turn the cap slowly approx-
imately one half turn to the left to re-
lease any excess pressure.

Continue turning the cap to the left and
remove it.The coolant level is correct if the level


for cold coolant: reaches the black
top part of the reservoir


for warm coolant: is approx. 0.6 in
(1.5 cm) higher

Add coolant as required.

Replace and tighten cap.
More information on coolant can be found
in the “Technical data” section
(
page 336).
Warning!
G
In order to avoid any possibly serious burns:

Use extreme caution when opening the
hood if there are any signs of steam or
coolant leaking from the cooling system,
or if the coolant temperature gauge indi-
cates that the coolant is overheated.


Do not remove pressure cap on coolant
reservoir if engine temperature is
above 194°F (90°C). Allow engine to
cool down before removing cap. The
coolant reservoir contains hot fluid and
is under pressure.


Using a rag, slowly open the cap approx-
imately
1/2 turn to relieve excess pres-
sure. If opened immediately, scalding
hot fluid and steam will be blown out un-
der pressure.


Do not spill antifreeze on hot engine
parts. Antifreeze contains ethylene gly-
col which may burn if it comes into con-
tact with hot engine parts.

264 Practical hintsWhat to do if …#
BATTERY/ALTERNATOR
VISIT WORKSHOP!
The battery is no longer charging.
Possible causes:

alternator malfunctioning


broken poly-V-belt

Stop immediately and check the
poly-V-belt.
If it is broken:

Do not continue to drive. Otherwise
the engine will overheat due to an
inoperative water pump which may
result in damage to the engine. Notify
an authorized Mercedes-Benz Center.
If it is intact:

Drive immediately to the nearest
authorized Mercedes-Benz Center.
!
(Canada
only)
;
(USA only)
PARKING BRAKE
RELEASE PARKING BRAKE!
You are driving with the parking brake
set.

Release the parking brake
(page 51).
Display
Possible cause
Suggested solution

266 Practical hintsWhat to do if …Display
Possible cause
Suggested solution
B
COOLANT
CHECK LEVEL!
The coolant level is too low.

Add coolant (
page 238).

If you have to add coolant frequently,
have the cooling system checked by
an authorized Mercedes-Benz Center.
Warning!
G
Do not spill antifreeze on hot engine parts.
Antifreeze contains ethylene glycol which
may burn if it comes into contact with hot
engine parts. You can be seriously burned.
!Do not ignore the low engine coolant
level warning. Extended driving with
the message and symbol displayed
may cause serious engine damage not
covered by the Mercedes-Benz Limited
Warranty.
Do not drive without sufficient amount
of coolant in the cooling system. The
engine will overheat causing major en-
gine damage.

267 Practical hints
What to do if …
During severe operating conditions and
stop-and-go city traffic, the coolant tem-
perature may rise close to 248°F (120°C).
Display
Possible cause
Suggested solution
Ï
COOLANT
STOP, ENGINE OFF!
The coolant is too hot.

Stop the vehicle and turn off the
engine.

Only start the engine again after the
message disappears. You could other-
wise damage the engine.
Warning!
G
Driving when your engine is badly overheat-
ed can cause some fluids which may have
leaked into the engine compartment to
catch fire. You could be seriously burned.
Steam from an overheated engine can cause
serious burns and can occur just by opening
the engine hood. Stay away from the engine
if you see or hear steam coming from it.
Turn off the engine, get out of the vehicle
and do not stand near the vehicle until it
cools down.
!The engine should not be operated with
the coolant temperature above 248°F
(120°C). Doing so may cause serious
engine damage which is not covered by
the Mercedes-Benz Limited Warranty.