2008 MERCEDES-BENZ CLS63AMG engine overheat

137 Controls in detail
Instrument cluster
Coolant temperature indicatorResetting trip odometer
Make sure you are viewing the trip odome-
ter display (
page 139).
If it is not displayed, press the è or
ÿ repeatedly until the trip odome-
ter appears.
Press and hold the reset button
(
page 136) 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 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 the
coolant temperature warning lamp (
page 350)
and a warning in the multifunction display
(
page 376).
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 Warran-
ty.
iDuring severe operating conditions, e.g.
stop-and-go traffic, the coolant temperature may
rise close to 248°F (120°C).

272 Operation
Driving instructions
Power assistanceBrakes
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.
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
vehicle.
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 and ignition must be shut off
(SmartKey in starter switch position0 or1 or
KEYLESS-GO* start/stop button in position0
or1) when testing the brakes on a brake test dy-
namometer and such testing should be no longer
than 10 seconds.
Active braking action through ESP
® may other-
wise seriously damage the brake system which is
not covered by the Mercedes-Benz Limited War-
ranty.

273 Operation
Driving instructions
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 in the res-
ervoir.
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 347).
Observe additional messages in the multi-
function display that may appear
(
page 374).
Have the brake system inspected immedi-
ately. 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
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 will cool down
the brakes faster.
Warning!G
Make sure not to endanger any other road
users when carrying out these braking ma-
neuvers.
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.
Be certain to read and observe the warning
notices on brake pad replacement
(
page 373).
!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.

281 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
control of the pollutants in the exhaust
emissions. 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. Moreover, the specified service
procedures must be carried out regularly
according to Mercedes-Benz servicing
requirements. For details 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, which could
potentially start a fire.
Warning!G
As with any vehicle, do not idle, park or
operate this vehicle in areas where combus-
tible 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.

282 Operation
Driving instructions
Coolant temperature
During severe operating conditions and
stop-and-go city 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
engine 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
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 the
engine has cooled down.

286 Operation
Engine compartment
Hood
Opening
1Release lever
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. 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, 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
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 (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
turned manually

290 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 driver’s side of the engine compart-
ment.
1Marking bar in the expansion tank
2Cap
3Coolant expansion tank
Using a rag, turn cap2 slowly approx-
imately one half turn counterclockwise
to release any excess pressure.
Continue turning cap2 counterclock-
wise and remove it.
The coolant level is correct if the level:

for cold coolant: reaches marking
bar1 in expansion tank3

for warm coolant: is approximately
0.6 in (1.5 cm) higher
Add coolant as required.
Replace and tighten cap2.
For more information on coolant, see the
“Technical data” section (
page 452).
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
under 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.

350 Practical hints
What to do if …
ProblemPossible cause/consequenceSuggested solution
DThe red coolant temperature
warning lamp comes on when
the engine is running.There is insufficient coolant in the reservoir.
If this warning lamp comes on frequently,
there is a leak in the cooling system.
If the coolant level is correct, the electric
radiator fan may be broken.Immediately add coolant to prevent
engine from overheating
(
page 290).
Have the cooling system checked.
If the coolant temperature is below
248°F (120°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.
DThe red coolant temperature
warning lamp comes on while
driving and you hear a warning
sound.The coolant temperature has exceeded
248°F (120°C).Stop in a safe location as soon as pos-
sible and allow the engine and coolant
to cool down.
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 which can occur just by open-
ing the engine hood. Stay away from the en-
gine 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.