engine overheat MERCEDES-BENZ CLK430 CABRIOLET 2003 C208 Owner's Manual

82 Instrument cluster
Te ch n i c a l
data Instruments
and controlsOperationDrivingInstrument
cluster displayPractical hints Car care Index
Coolant temperature gauge (3)
During severe operating conditions and stop-and-go city
traffic, the coolant temperature may rise close to the red
marking.
The engine should not be operated with the coolant
temperature in the red zone. Doing so may cause
serious engine damage which is not covered by the
Mercedes-Benz Limited Warranty.Outside temperature indicator (5)
The temperature sensor is located in the front bumper
area. Due to its location, the sensor can be affected by
road or engine heat during idling or slow driving. This
means that the accuracy of the displayed temperature
can only be verified by comparison to a thermometer
placed next to the sensor, not by comparison to external
displays (e.g. bank signs etc.).
Adaptation to ambient temperature takes place in steps
and depends on the prevailing driving conditions (stop-
and-go or moderate, constant driving) and amount of
temperature change.
Wa r n i n g !
• Driving when your engine is badly 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 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.
Wa r n i n g !
The outside temperature indicator is not designed
to serve as an Ice-Warning Device and is therefore
unsuitable for that purpose. Indicated
temperatures just above the freezing point do not
guarantee that the road surface is free of ice.

165 Soft top
Te ch n i c a l
data Instruments
and controlsOperationDrivingInstrument
cluster displayPractical hints Car care Index If the indicator lamp in the soft top switch blinks slowly
while activating the switch,
•the battery voltage may be insufficient – start
engine and let it run while activating switch,
•the system may be overheated (for example after
lowering or raising the soft top approx. 5
consecutive times) – after approx. 10 minutes the
soft top switch may be activated again.
If indicator lamp in the soft top switch blinks rapidly
while activating the switch,
•the trunk lid and/or the luggage cover may be open,
and need to be closed,
•the soft top is still locked during the opening
procedure and needs to be unlocked,
•the opening/closing procedure is interrupted.
In this case the soft top needs to be synchronized.
Turn electronic key in steering lock back to
position 0, and then to position 2. Activate soft top
switch again. The soft top should now be operational
again.
If the indicator lamp continues to blink, raise the soft
top manually, see page 288. Have the system checked at your authorized
Mercedes-Benz Center as soon as possible.
Notes:
If the roll bar was raised automatically, the process of
raising or lowering the soft top will take somewhat
longer, as the roll bar must first be lowered.
Whenever possible, park vehicle in the shade as
continuous exposure to sun rays can prematurely
deteriorate the soft top material.
The soft top may become moldy and receive permanent
creases if it is kept in the storage compartment for an
extended period.
Therefore, we recommend raising and airing it
thoroughly with the side windows open (do not expose
it to the sun) at regular intervals during the wet and
cold seasons.
To prevent damage, the soft top must be dry and clean
before lowering it into the storage compartment. There
is the possibility of sharp-edged dirt particles damaging
the soft top or scratching the rear window.

176 Catalytic converter
Te ch n i c a l
data Instruments
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Catalytic converter
Your Mercedes-Benz is equipped with monolithic type
catalytic converters, an important element in
conjunction with the oxygen sensors to achieve
substantial control of the pollutants in the exhaust
emissions. Keep your vehicle in proper operating
condition by following our recommended maintenance
instructions as outlined in your Service Booklet.Caution!
To prevent damage to the catalytic converters, 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, which could start a fire.
Wa r n i n g !
As with any vehicle, do not idle, park or operate
this vehicle in areas where combustible 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.

202 Driving instructions
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data Instruments
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Power assistance
BrakesExcessive use of salt and other snow melting chemicals
spread on roads during the winter months may cause a
build up of moisture or residue to form on the braking
components. This build up or residue could cause light
corrosion of the braking components if the vehicle is
parked with the brakes cold. Apply steady and even
braking pressure when stopping the vehicle to warm up
and dry the brake components.
Important!
Please pay attention to the function of the brake assist
system (BAS), see page 212.
If the parking brake is released and the brake warning
lamp in the instrument cluster stays on, the brake fluid
level in the reservoir is too low.
Brake pad wear or a leak in the system may be the
reason for low brake fluid in the reservoir.
Have the brake system inspected at an authorized
Mercedes-Benz Center immediately.
Wa r n i n g !
When the engine is not running, the brake and
steering systems are without power assistance.
Under these circumstances, a much greater effort is
necessary to stop or steer the vehicle.Wa r n i n g !
After driving in heavy rain for some time without
applying the brakes or through water deep enough
to wet brake components or salty road conditions,
the first braking action may be somewhat reduced
and increased pedal pressure may be necessary to
obtain expected braking effect. Be sure to 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 effectiveness. It may
not be possible to stop the vehicle in sufficient time
to avoid an accident.

203 Driving instructions
Te ch n i c a l
data Instruments
and controlsOperationDrivingInstrument
cluster displayPractical hints Car care Index All checks and service work on the brake system should
be carried out by an authorized Mercedes-Benz Center.
Install only brake pads and brake fluid recommended by
Mercedes-Benz.
Caution!
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.
After hard braking, it is advisable to drive on for some
time, rather than immediately parking, so the air stream
will cool down the brakes faster.Driving off
Apply the service 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 operating temperature has been
reached.
When starting off on a slippery surface, do not allow one
drive wheel to spin for an extended 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.
Wa r n i n 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.

232 Malfunction and warning messages
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data Instruments
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BATTERY/ALTERNATORThis message indicates a malfunction which must be
repaired immediately.
It may indicate that the poly-V-belt has broken. Should
this condition occur, the poly-V-belt must be replaced
before continuing to operate the vehicle. Otherwise, the
engine will overheat due to an inoperative water pump
which may result in damage to the engine.
Do not continue to drive the vehicle with this message
displayed.
Doing so could result in serious engine damage that is
not covered by the Mercedes-Benz Limited Warranty.
Line 1 Line 2
BATTERY/ALTERNATOR VISIT WORKSHOP!
OVERVOLTAGE VISIT WORKSHOP!
UNDERVOLTAGE CONSUMER DEFECTIVE!

236 Malfunction and warning messages
Te ch n i c a l
data Instruments
and controlsOperation DrivingInstrument
cluster displayPractical hints Car care Index
COOLANT (coolant level)
When this message appears while driving, the coolant
level has dropped below the required level. If no leaks
are noticeable and the engine temperature does not
increase, continue to drive to the nearest service station
and have coolant added to the coolant system.The low engine coolant level warning should not be
ignored. Extended driving with the symbol displayed
may cause serious engine damage not covered by the
Mercedes-Benz Limited Warranty.
In cases of major or frequent minor coolant loss, have
the cooling system checked at your authorized
Mercedes-Benz Center as soon as possible.
Notes:
Do not drive without sufficient amount of coolant in the
cooling system. The engine will overheat causing major
engine damage.
Monitor the coolant temperature gauge while driving.
See page 253 for instructions on adding coolant.
Line 1 Line 2
COOLANT CHECK LEVEL!
Wa r n i n 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.

237 Malfunction and warning messages
Te ch n i c a l
data Instruments
and controlsOperation DrivingInstrument
cluster displayPractical hints Car care Index COOLANT TEMP. (coolant temperature)
1 Observe coolant temperature gauge, see page 82.
Check coolant level, see page 253.
This may indicate that the poly-V-belt has broken. Should this
condition occur, the poly-V-belt must be replaced before continuing
to operate the vehicle. Otherwise, the engine will overheat due to
an inoperative water pump which may result in damage to the
engine. Do not continue to drive the vehicle with this message
displayed. Doing so could result in serious engine damage that is
not covered by the Mercedes-Benz Limited Warranty.
During severe operating conditions and stop-and-go city
traffic, the coolant temperature may rise close to the red
marking.
The engine should not be operated with the coolant
temperature in the red zone. Doing so may cause
serious engine damage which is not covered by the
Mercedes-Benz Limited Warranty.
Line 1 Line 2
COOLANT TEMP. VISIT WORKSHOP!
1
Wa r n i n g !
Driving when your engine is badly 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 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.

250 Engine compartment
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data Instruments
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cluster displayPractical hintsCar care Index
Hood
Wa r n i n g !
To help prevent personal injury, stay clear of
moving parts when the hood is open and the engine
is running. Be sure the hood is properly closed
before driving. When closing hood, use extreme
caution not to catch hands or fingers.The radiator fan may continue to run for
approximately 30 seconds or even restart after the
engine has been turned off. Stay clear from fan
blades.
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, diagnostic socket) of the
ignition system
• with the engine running,
• while starting the engine,
• if ignition is “on” and the engine is turned
manually.If you see flames, steam or smoke coming from the
engine compartment, or if the coolant temperature
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 a fire department.

254 Engine compartment
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data Instruments
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cluster displayPractical hintsCar care Index
Adding coolant
If coolant has to be added, a 50 / 50 mixture of water and
MB anticorrosion / antifreeze should be added.
The drain plugs for the cooling system are located on
the right side of the engine block and at the bottom of
the radiator.
Anticorrosion / antifreeze mixture, see page 321.
Wa r n i n g !
In order to avoid possible serious burns or injury:
• 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 indicates 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 cap approximately
1/2 turn to relieve excess pressure. If opened
immediately, scalding hot fluid and steam will
be blown out under pressure.• Do not spill antifreeze on hot engine parts.
Antifreeze contains ethylene glycol which may
burn if it comes into contact with hot engine
parts.