2008 MERCEDES-BENZ CL-Class engine overheat

435 Controls in detail
Instrument cluster
Coolant temperature gauge
The coolant temperature gauge is on the
left side in the instrument cluster
(page 30).
Tachometer
The red marking on the tachometer de-
notes excessive engine speed.
To help protect the engine, the fuel supply
is interrupted if the engine is operated
within the red marking.
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 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.
!
Excessive coolant temperature triggers a
warning in the multifunction display
(
page 657).
The engine should not be operated with the cool-
ant temperature above 248°F (120°C), i.e. in
the red zone of the coolant temperature gauge.
Doing so may cause serious engine damage
which is not covered by the Mercedes-Benz Lim-
ited Warranty.
i
During severe operating conditions,
e.g. stop-and-go traffic, the coolant temperature
may rise close to 248°F (120°C), i.e. close to
the red zone of the temperature gauge.
!
Avoid driving at excessive engine speeds, as
it may result in serious engine damage that is not
covered by the Mercedes-Benz Limited
Warranty.

540 OperationDriving instructionsBrakes
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-
jected 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 or BAS Plus*) (
page 67).
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 red brake warning lamp in
the instrument cluster comes on while the
engine is running and an acoustic warning
sounds (
page 611). Observe additional
messages in the multifunction display that
may appear (page 622).
Have the brake system inspected
immediately. Contact an authorized
Mercedes-Benz Center.
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
effect. 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
accident.
!
Because the ESP
® operates automatically,
the engine and ignition must be shut off
(SmartKey in starter switch position0 or1 or
KEYLESS-GO start/stop button* in position0
or1) when


the electronic parking brake is being tested
on a brake test dynamometer


the vehicle is being towed with the
front/rear 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 ma-
neuvers.

541 Operation
Driving instructions
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
recommended 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.High-performance brake system
(CL 63 AMG and CL 65 AMG only)
The high-performance brake system is de-
signed to operate under the extremely high
operating demands required to accommo-
date the performance capabilities of the
vehicle. The brakes may produce a squeak-
ing-type noise depending on the


vehicle speed


brake force applied


ambient conditions, e.g. temperature
and humidity
As with any brake system, the wear of indi-
vidual brake system components such as
brake pads or disks strongly depends on
your driving style and the conditions under
which you operate the vehicle. Thus, a driv-
ing style calling for high demand braking
will cause your vehicle’s brakes to wear
more quickly.
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 using the engine’s braking power, a drive
wheel may not spin for an extended period of
time, e.g. on slippery road surfaces.
This may cause serious damage to the drivetrain
which is not covered by the Mercedes-Benz Lim-
ited Warranty.

548 OperationDriving instructionsCatalytic 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.
Emission control
Certain parts of the engine and the emis-
sion 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.
!
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.
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.

549 Operation
Driving instructions
Coolant temperature
During severe operating conditions,
e.g. stop-and-go traffic, the coolant tem-
perature 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 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 (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.
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.

554 OperationEngine compartment
Closing
Let the hood drop from a height of ap-
proximately 1 ft (30 cm).
The hood will lock audibly.

Check to make sure the hood is fully
closed.
If you can raise the hood at a point
above the headlamps, then it is not
properly closed. Open it again and let it
drop with somewhat greater force.
Engine oil
The amount of oil your engine needs will
depend on a number of factors, including
driving style. Higher oil consumption can
occur when

the vehicle is new


the vehicle is driven frequently at
higher engine speeds
Engine oil consumption checks should only
be made after the vehicle break-in period.
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
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
Warning!
G
When closing the hood, use extreme caution
not to catch hands or fingers. Be careful that
you do not close the hood on anyone.
Make sure that the hood is securely en-
gaged before driving off. Do not continue
driving if the hood can no longer engage af-
ter an accident, for example. The hood could
otherwise come loose while the vehicle is in
motion and endanger you and/or others.
!
Do not use any special lubricant additives,
as these may damage the drive assemblies. Us-
ing special additives not approved by
Mercedes-Benz may cause damage not covered
by the Mercedes-Benz Limited Warranty.
More information on this subject is available at
any Mercedes-Benz Center.


559 Operation
Engine compartment
Coolant level
The engine coolant is a mixture of water
and anticorrosion/antifreeze.
When checking the coolant level,

the vehicle must be parked on level
ground


the coolant temperature must be
below 158°F (70°C)
The coolant expansion tank is located on
the passenger side of the engine compart-
ment.
Example illustration from CL 5501Cap
2Coolant expansion tank

Using a rag, turn cap1 slowly approx-
imately one half turn counterclockwise
to release any excess pressure.

Continue turning the cap counterclock-
wise and remove it.
The coolant level is correct if the level


for cold coolant: reaches the white
marking (plastic bridge) inside the cool-
ant expansion tank


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

Add coolant as required.

Replace and tighten cap1.
For more information on coolant, see the
“Technical data” section (
page 738).
Warning!
G
In order to avoid 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 gauge indi-
cates that the coolant is overheated.


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

625 Practical hints
What to do if …?
Display
Possible cause/consequence
Possible solution
DISTRONIC PLUS
Currently Unavailable
See Oper. Manual
DISTRONIC Plus* is switched off and is
temporarily unavailable.
DISTRONIC Plus* is deactivated if:

the DISTRONIC Plus* cover in the radi-
ator grille is dirty


the radar sensors* do not sense any
other vehicles or objects, i.e. road sign
or similar to this, for a long time


the system is overheated


its function is impaired as a result of
heavy precipitation or fog


the battery voltage is insufficient

Clean the DISTRONIC Plus* cover in the radiator grille
(page 599).

Restart the vehicle.

Try activating DISTRONIC Plus* again later.

Wait until the system cools down or the battery recovers.
DISTRONIC Plus* will be operational again without you needing to
restart the engine if:


the dirt (e.g. slush) loosens while you are driving


the system detects that the sensors* are fully available again


the message in the multifunction display disappears
DISTRONIC Plus* is switched off because
the radar sensor system* is temporarily in-
operative due to electromagnetic interfer-
ence near television and radio transmitter
stations, toll stations, speed measuring
systems, etc.

Wait until the message in the multifunction display disappears.