engine overheat MERCEDES-BENZ CLK350 COUPE 2007 C209 Owner's Manual

139 Controls in detail
Instrument cluster
Coolant temperature indicator
The coolant temperature indicator is on
the right side in the instrument cluster
(
page 26).
Resetting trip odometer
Make sure you are viewing the stan-
dard display in the multifunction dis-
play (
page 146).
If it is not displayed, press buttonè
orÿ on the multifunction steering
wheel repeatedly until the standard dis-
play appears (
page 142).
Press and hold the reset button on the
instrument cluster (
page 138) until
the trip odometer is reset.
Warning!G

Driving when your engine is overheated
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 which can occur
just by opening the hood. Stay away
from the engine if you see or hear steam
coming 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.
!Excessive coolant temperature triggers a
warning in the multifunction display
(
page 381) and the red coolant warning lamp
in the instrument cluster comes on
(
page 361).
The engine should not be operated with the cool-
ant temperature above 248°F (120°C). Doing so
may cause serious engine damage which is not
covered by the Mercedes-Benz Limited
Warranty.
iDuring severe operating conditions, e.g.
stop-and-go traffic, the coolant temperature may
rise close to 248°F (120°C).

294 Operation
Driving instructions
Power assistance
Brakes
To 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 sub-
ject to moderate loads, you should occa-
sionally 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.
Refer to the description of the Brake Assist
System (BAS) (
page 90).
Brake pad wear or a leak in the system may
be the reason for low brake fluid level in
the reservoir.
The brake fluid level in the reservoir may
be too low if the brake warning lamp in the
instrument cluster comes on and an
acoustic warning sounds although the
parking brake is released (
page 358).
Warning!G
With the engine not running, there is no
power assistance for the brake and steering
systems. In this case, it is important to keep
in mind that a considerably higher degree of
effort is necessary to brake and steer the ve-
hicle.
Warning!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.
!Because the ESP® operates automatically,
the engine must be shut off when

the parking brake is being tested on a brake
test dynamometer

the vehicle is being towed with the front axle
raised
Active braking action through the ESP
® may oth-
erwise seriously damage the brake system.
Warning!G
Make sure not to endanger any other road
users when carrying out these braking
maneuvers.

295 Operation
Driving instructions
Observe additional messages in the multi-
function display that may appear
(
page 379).
Have the brake system inspected
immediately. Contact an authorized
Mercedes-Benz Center.
All checks and service work on the brake
system should be carried out by qualified
technicians only. Contact an authorized
Mercedes-Benz Center.
Only install brake pads and brake fluid rec-
ommended by Mercedes-Benz.
After hard braking, it is advisable to drive
on for some time, rather than immediately
park, so that the air stream can 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 gradually. Do not
place full load on the engine until the oper-
ating temperature has been reached.
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
could 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 prevent overheating of the brakes and
reduces brake pad wear.
!When driving off on a slippery surface, do
not allow a drive wheel to spin for an extended
period with the ESP
® switched off. Doing so may
cause serious damage to the drivetrain which is
not covered by the Mercedes-Benz Limited
Warranty.
!Simultaneously depressing the accelerator
pedal and applying the brake reduces engine
performance and causes premature brake wear
and drivetrain wear.

301 Operation
Driving instructions
Telephones* and two-way radios
Radio transmitters, such as a mobile
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
antenna.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
recommended maintenance instructions
as outlined in your Maintenance Booklet.
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 serious
personal injury.
!To prevent damage to the catalytic
converters, 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.
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.

302 Operation
Driving instructions
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 to 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 accord-
ing to Mercedes-Benz servicing require-
ments. For details refer to the
Maintenance Booklet.
Coolant temperature
During severe operating conditions and
stop-and-go city traffic, the coolant
temperature may rise close 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
engine 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 (CO), and inhaling it can cause un-
consciousness 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 with at least one window
fully open at all times.
Warning!G

Driving when your engine is overheated
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 which can occur
just by opening the 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 the
engine has cooled down.

306 Operation
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 indicator 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.
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, only touch owner serviceable
components described in the Operator’s
Manual and 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
approximately 30 seconds or even restart
after 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
(ignition coils, spark plug sockets, diagnos-
tic socket) of the ignition system

with the engine running

while starting the engine

if the ignition is “on” and the engine is
turned manually.

310 Operation
Engine compartment
Coolant
The engine coolant is a mixture of water
and anticorrosion/antifreeze. To check
the coolant level, the vehicle must be
parked on level ground and the engine
must be cool.
The coolant expansion tank is located on
the passenger side of the engine
compartment.
1Coolant expansion tank
2CapUsing a rag, turn cap 2 slowly
approximately one half turn counter-
clockwise to release any excess pres-
sure.
Continue turning the cap 2 counter-
clockwise and remove it.
The coolant level is correct if the level

for cold coolant: reaches the marking
(plastic bridge) inside the reservoir

for warm coolant: is approx. 0.6 in
(1.5 cm) higher
Add coolant as required.
Replace and tighten cap 2.
More information on coolant can be found
in the “Technical data” section
(
page 453).
Warning!G
In order to avoid any potentially 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 indicator
indicates that the coolant is overheated.

Do not remove pressure cap on coolant
reservoir if the coolant temperature is
above 158°F (70°C). Allow the coolant
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.

361 Practical hints
What to do if …?
ProblemPossible cause/consequenceSuggested solution
•The red coolant warning lamp
comes on when the engine is
running.There is insufficient coolant in the reservoir.Add coolant to prevent engine from
overheating (
page 310).
If this warning lamp comes on frequently,
there is a leak in the cooling system.Have the cooling system checked.
If the coolant level is correct, the electric ra-
diator fan may be broken.If the coolant temperature is below
257 °F (125 °C), you can continue
driving to the nearest authorized
Mercedes-Benz Center.
Avoid high engine loads (e.g. driving
uphill) and stop-and-go driving.
•The red coolant warning lamp
comes on while driving and you
hear a warning sound.The coolant temperature has exceeded
257 °F (125 °C).Stop as soon as possible and allow
the engine and coolant to cool down.
Warning!G
Driving when your engine is overheated 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 which can occur just by open-
ing the 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 the
engine has cooled down.

378 Practical hints
What to do if …?
Symbol messages
Display symbolDisplay messagePossible cause/consequencePossible solution
#The battery is no longer charging.
Possible causes:

broken poly-V-belt

alternator malfunctioning
Stop immediately in a safe location or
as soon as it is safe to do so 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.
Low voltage
Charge batteryThe battery has insufficient voltage.Start the engine (page 50).
Low voltage
Switch off
consumersThe battery has insufficient voltage.Turn off unnecessary electrical con-
sumers.

380 Practical hints
What to do if …?
Display symbolDisplay messagePossible cause/consequencePossible solution
úVisit workshopThere may be a malfunction in the

fuel injection system

ignition system

exhaust system

fuel system
Have the measuring system checked
by an authorized Mercedes-Benz Cen-
ter.
B Top up coolant
See Operator’s ManualThe coolant level is too low.Add coolant (page 310).
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 could 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 Lim-
ited Warranty.
Do not drive without sufficient amount of coolant
in the cooling system. The engine will overheat,
causing major engine damage.