2008 MERCEDES-BENZ GL450 open hood

380 Operation
Engine compartment
Engine oil
The amount of oil your engine needs will
depend on a number of factors, including
driving style. Increased 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.Checking engine oil level
When checking the oil level

the vehicle must be parked on level
ground

the vehicle must have been stationary
for at least 5 minutes with the engine
turned off
Example illustration GL 450 (GL 320 CDI,
GL 550 similar)
1Oil dipstick
2Upper mark
3Lower mark
Open the hood (page 378).
Pull out oil dipstick1.
Wipe oil dipstick1 clean.
Fully insert oil dipstick1 into the
dipstick guide tube.
Pull out oil dipstick1 again after
approximately 3 seconds to obtain
accurate reading.
The oil level is correct when it is be-
tween lower mark3 (min.) and upper
mark2 (max.) of the oil dipstick.
If necessary, add engine oil
(
page 381).
For more information on engine oil, see
“Technical data” section (
page 562) and
(
page 564).
!Do not use any special lubricant additives,
as these may damage the drive assemblies.
Using 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 Light Truck Center.
iThe filling quantity between the upper and
lower marks on the oil dipstick is approximately
2.1 US qt. (2.0 l).
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382 Operation
Engine compartment
The coolant expansion tank is located on
the driver’s side of the engine compart-
ment.
1Cap
2Coolant expansion tank
3Indicator wall
4Coolant levelUsing a rag, turn cap1 slowly approx-
imately one half turn counterclockwise
to release any excess pressure.
Continue turning cap1 counterclock-
wise and remove it.
Coolant level4 is correct if the level:

for cold coolant: reaches the top of
indicator wall3 visible through the
filling opening

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
“Coolants” (
page 567).
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 display
indicates 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
glycol which may burn if it comes into
contact with hot engine parts.
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471 Practical hints
What to do if …
During severe operation conditions and
stop-and-go city traffic, the coolant tem-
perature may rise close to 248°F (120°C).
Display symbolDisplay messagePossible cause/consequencePossible solution
Observe the coolant temperature in the
multifunction display (
page 162).
If the temperature raises again:
Contact an authorized Mercedes-Benz
Light Truck Center immediately.
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.
!The engine should not be operated with the
coolant temperature above 248°F (120°C).
Doing so may cause serious damage which is not
covered by the Mercedes-Benz Limited
Warranty.
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474 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
c You are driving with one or more
doors open.Stop the vehicle in a safe location or as
soon as it is safe to do so.
Close the door(s).
] Clean
Fuel FilterContact an authorized Mercedes-Benz
Light Truck Center.
AGas Cap OpenA loss of pressure has been
detected in the fuel system. The
fuel cap may not be closed
properly or the fuel system may
be leaky.Check the fuel cap (page 374).
If it is not closed properly:
Close the fuel cap.
If it is closed properly:
Have the fuel system checked by an
authorized Mercedes-Benz Light Truck
Center.
aYou are driving with the hood or
the tailgate open.Carefully bring the vehicle to a halt as
soon as it is safe to do so in a safe
location.
Close the hood (page 379) or the
tailgate (
page 123).
You are trying to lock the vehicle
with the KEYLESS-GO* function
with a door or the tailgate open.Close all doors and/or the tailgate
(
page 123).
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507 Practical hints
Replacing bulbs
Replacing bulbs for front lamps
Before you start to replace a bulb for a
front lamp, do the following first:
Turn the exterior lamp switch to
positionM (
page 143).
Open the hood (page 378).
1Housing cover for low beam halogen
headlamp
2Housing cover for high beam halogen
bulb (high beam and high beam flasher)
3Bulb socket for parking and standing
lamp bulb
4Bulb socket for turn signal lamp bulb
5Bulb socket for side marker lamp bulbLow beam bulb (halogen headlamp)
1Low beam headlamp cover
2Bulb socket for low beam headlamp
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514 Practical hints
Replacing bulbs
License plate lamp
1License plate lamp cover
2Screws
Loosen screws2.
Remove license plate lamp cover1.
Replace the tubular bulb.
Reinstall license plate lamp cover1.
Retighten screws2.
Adjusting headlamp aim
VVertical centerline
HHeadlamp mounting height, measured
from the centerCorrect headlamp adjustment is extremely
important. To check and readjust a head-
lamp, follow the steps described:
Park the vehicle on a level surface
25 feet (7.6 m) from a vertical test
screen or wall.
Switch the headlamps on
(
page 143).
If the beam does not show a beam pattern
as indicated in the figure left, then follow
the steps below:
Open hood (page 378).
iHigh beam adjustments simultaneously aim
the low beam.
Vehicle should have a normal tailgate load.
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516 Practical hints
Replacing wiper blades
Front wiper blades
Removing
Remove the SmartKey from the starter
switch.
Vehicles with KEYLESS-GO*:
Make sure the vehicle’s on-board
electronics have status0
(
page 44).
Fold the wiper arms forward until they
engage.
1Wiper blade
2Cover
3Attachment
4Tab
5Removing
Press tabs4 together and tilt wiper
blade1 to detach tabs4 on both
recesses of attachment3.
Wiper blade1 is released on one end.
Maintaining its tilted position, slide
wiper blade1 out of attachment3 in
direction of arrow5.
Warning!G
For safety reasons, switch off wipers and
remove SmartKey from starter switch (vehi-
cles with KEYLESS-GO*: Make sure the
vehicle’s on-board electronics have
status
0) before replacing a wiper blade.
Otherwise the motor could suddenly turn on
and cause injury.
Warning!G
Wiper blades are components that are sub-
ject to wear and tear. Replace the wiper
blades twice a year, preferably in the spring
and fall. Otherwise the windows will not be
properly wiped. As a result, you may not be
able to observe surrounding traffic condi-
tions and could cause an accident.
!Never open the hood when the wiper arms
are folded forward.
Hold on to the wiper when folding the wiper arm
back. If released, the force of the impact from
the tensioning spring could crack the windshield.
Do not allow the wiper arms to contact the wind-
shield glass without a wiper blade inserted.
Make sure the wiper blades are properly
installed. Improperly installed wiper blades may
cause windshield damage.
For your convenience, we recommend that you
have this work carried out by an authorized
Mercedes-Benz Light Truck Center.
!Do not pull on the wiper blade inserts. They
could tear.
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537 Practical hints
Jump starting
The jump-start contacts are located in the
engine compartment.
1Negative (-) terminal
2Positive (+) terminal
3Positive terminal cover
Make sure the two vehicles do not
touch.
Turn off all electrical consumers.
Apply parking brake (page 67).
Set automatic transmission to
positionP (
page 191).
Open the hood (page 378).
Remove cover from negative
terminal1.
Flip up cover3 of positive terminal2
in direction of arrow.
1Negative terminal of discharged
battery
2Positive terminal of discharged battery
4Positive terminal of charged battery
5Negative terminal of charged battery
Connect positive terminal2 and4
with the jumper cable. Clamp cable to
charged battery4 first.
Start engine of the vehicle with the
charged battery and run at idle speed.
Connect negative terminals1 and5
of the batteries with the second jumper
cable. Clamp the cable to negative
terminal5 of the charged battery
first.
Start the engine of the disabled vehi-
cle.
You can now turn on the electrical consum-
ers. Do not switch on the headlamps under
any circumstances.
Remove the jumper cables first from
negative terminals1 and5 and then
from positive terminals2 and4.
You can now switch on the headlamps.
Have the battery checked at the near-
est authorized Mercedes-Benz Light
Truck Center.
Warning!G
Keep flames or sparks away from battery.
Do not smoke.
Observe all safety instructions and precau-
tions when handling automotive batteries
(
page 528).
!Never invert the terminal connections!
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