cooling MERCEDES-BENZ ML500 1997 Complete Repair Manual

99 Climate control
Te ch n ica l
data Instruments
and controlsOperationDrivingInstrument
cluster displayPractical hints Car care Index 1Air volume control switch
2Temperature selector switch
3Air distribution switch
4Air recirculation
5Air conditioning mode
6Air volume control for center air outlets,
turn wheel up to open.
7Air volume control for side air outlet,
turn wheel up to open.
8Center air outlets, adjustable
9Side air outlets, adjustable
10Windshield air outlets
11Floor outlets
The air conditioning mode only operates with the œ
button pushed, the air volume control switch set to
position 1 to 4, and the engine running.To quickly cool down the passenger compartment, turn
temperature selector switch fully to the left to
positionO. Turn temperature selector to maintain
desired temperature.
The air conditioning mode removes considerable
moisture from the air during operation in the cooling
mode. It is normal for water to drip on the ground
through ducts in the underbody.
Important!
This vehicle is equipped with an air conditioner system
that uses R–134a (HFC: hydrof luorocarbon) as a
refrigerant. Repairs should always be performed by a
qualified technician, and refrigerant should be collected
in a recovery system for recycling.
Note:
For the air flow-through system to function properly, the
air vents, located in the left and right side rear
passenger compartment trim panel covers, should be
ke pt un obst ru cte d .

224 Malfunction and indicator lamps
Te ch n ica l
data Instruments
and controlsOperation DrivingInstrument
cluster displayPractical hints Car care Index
Low engine oil level warning lamp
With the key in steering lock position 2, the
oil level warning lamp comes on and should
go out when the engine is running.
If the warning lamp does not go out after starting the
engine, or comes on with the engine running and at
operating temperature, the engine oil level has dropped
to approximately the minimum mark on the dipstick.
When this occurs, the warning lamp will first come on
intermittently and then stay on if the oil level drops
further.
If no oil leaks are noted, continue to drive to the nearest
service station where the engine oil should be topped to
the “full” mark on the dipstick with an approved oil.
The low engine oil level warning light should not be
ignored. Extended driving with the light illuminated
could result in serious engine damage that is not
covered by the Mercedes-Benz Limited Warranty.
In addition to the warning lamp, the engine oil level
should be periodically checked with the dipstick or via
the oil level indicator in the odometer display field, for
example during a fuel stop, or before a long trip (see
engine oil level indicator on page 89 and checking
engine oil on page 233).Low engine coolant level warning
When the coolant level warning lamp comes
on while driving, then the coolant level has
dropped below the required level, or the
coolant temperature is in the red zone. 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, see
page 234. If the engine temperature reaches the red
zone, move vehicle to an area which is in a safe distance
from the roadway and turn off the engine. Also see
coolant temperature gauge on page 81.
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 Light Truck Center as soon as possible.
Notes:
Do not drive without coolant in the cooling system. The
engine will overheat causing major engine damage.
Monitor the coolant temperature gauge while driving.

235 Engine compartment
Te ch n ica l
data Instruments
and controlsOperation DrivingInstrument
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.
After adding coolant, close cap until you hear it click a
few times.
The drain plugs for the cooling system are located on
the left and right side of the engine block directly above
the engine mounts and at the bottom of the radiator.
Anticorrosion / antifreeze mixture, see page 297.
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.

293 Fuels, coolants, lubricants etc. - capacities
Te ch n ica l
data Instruments
and controlsOperation DrivingInstrument
cluster displayPractical hints Car care Index Brake system
(MB Brake fluid [DOT 4+])approx. 0.9 US qt (0.8 l)
Windshield / headlamp washer system
(MB Windshield washer concentrate “S”
1)Vehicles without
headlamp cleaning
system
Vehicles with headlamp
cleaning systemapprox. 5.5 US qt (5.0 l)
approx. 8.0 US qt (7.6 l)
Cooling system
(MB Anticorrosion / antifreeze)approx. 12.7 US qt (12.0 l)
Fuel tank
including a reserve of
(Premium unleaded gasoline:
Posted Octane 91 (Avg. of 96 RON / 86 MON))ML 320 / ML 430
ML 55 AMGapprox. 19.2 US gal (73.0 l)
approx. 3.2 US gal (12.0 l)
approx. 24.5 US gal (93.0 l)
approx. 3.2 US gal (12.0 l)
Air conditioner system
(R-134a refrigerant and special
PA C l u b r i c a n t (Never R-12))
1 Use MB Windshield Washer Concentrate “S” and water for temperatures above freezing or MB Windshield Washer Concentrate “S” and
commercially available premixed windshield washer solvent / antifreeze for temperatures below freezing. Follow suggested mixing ratios, see
page 237.Fuels, coolants, lubricants etc. Model Capacity

296 Fuels, coolants, lubricants etc.
Te ch n ica l
data Instruments
and controlsOperation DrivingInstrument
cluster displayPractical hints Car care Index
Gasoline additives
A major concern among engine manufacturers is carbon
build up caused by gasoline. Mercedes-Benz
recommends the use of only quality gasoline containing
additives that prevent the build up of carbon deposits.
After an extended period of using fuels without such
additives, carbon deposits can build up especially on the
intake valves and in the combustion area, leading to
engine performance problems such as:
•warm-up hesitation,
•unstable idle,
•knocking / pinging,
•misfire,
•power loss.
Do not blend other specific fuel additives with fuel.
They only result in unnecessary cost, and may be
harmful to the engine operation.
Damage or malfunctions resulting from poor fuel
quality or from blending specific fuel additives are not
covered by the Mercedes-Benz Limited Warranty.Coolants
The engine coolant is a mixture of water and
anticorrosion / antifreeze, which provides:
•corrosion protection,
•freeze protection,
•boiling protection (by increasing the boiling point).
The cooling system was filled at the factory with a
coolant providing freeze protection to approximately
-35°F (-37°C) and corrosion protection.
If the antifreeze mixture is effective to -22°F (-30°C), the
boiling point of the coolant in the pressurized cooling
system is reached at approx. 266°F (130°C).
The coolant solution must be used year round to provide
the necessary corrosion protection and increase in the
boil-over protection. You should have it replaced every
3years.
To provide the important corrosion protection, the
solution must be at least 45% anticorrosion / antifreeze
(equals a freeze protection to approx. - 22°F [-30°C]). If
you use a solution that is more than 55% anticorrosion/
antifreeze (freeze protection to approx. - 49°F [-45°C])-,

297 Fuels, coolants, lubricants etc.
Te ch n ica l
data Instruments
and controlsOperation DrivingInstrument
cluster displayPractical hints Car care Index the engine temperature will increase due to the lower
heat transfer capability of the solution. Therefore, do not
use more than this amount of anticorrosion / antifreeze.
If the coolant level is low, water and MB anticorrosion/
antifreeze should be used to bring it up to the proper
level (have cooling system checked for signs of leakage).
The water in the cooling system must meet minimum
requirements, which are usually satisfied by normal
drinking water. If your are not sure about the water
quality, consult your authorized Mercedes-Benz Light
Truck Center.
Anticorrosion/antifreeze
Your vehicle contains a number of aluminum parts. The
use of aluminum components in motor vehicle engines
necessitates that anticorrosion / antifreeze coolant used
in such engines be specifically formulated to protect the
aluminum parts. (Failure to use such anticorrosion/
antifreeze coolant will result in a significantly
shortened service life.)
Therefore the following product is strongly
recommended for use in your vehicle: Mercedes-Benz
Anticorrosion / antifreeze agent.Before the start of the winter season (or once a year in
the hot southern regions), you should have the
anticorrosion / antifreeze concentration checked. The
coolant is also regularly checked each time you bring
your vehicle to your authorized Mercedes-Benz Light
Truck Center for service.
Anticorrosion / antifreeze quantity
Approx. freeze protection
– 35°F
(– 37°C)– 49°F
(– 45°C)
6.4 US qt
(6.0 l)7. 0 U S q t
(6.6 l)

99
Climate control
Te ch n ica l
data
Instruments
and controls Operation
Driving Instrument
cluster display Practical hints Car care Index
1
Air volume control switch
2 Temperature selector switch
3 Air distribution switch
4 Air recirculation
5 Air conditioning mode
6 Air volume control for center air outlets,
turn wheel up to open.
7 Air volume control for side air outlet,
turn wheel up to open.
8 Center air outlets, adjustable
9 Side air outlets, adjustable
10 Windshield air outlets
11 Floor outlets
The air conditioning mode only operates with the œ
button pushed, the air volume control switch set to
position 1 to 4, and the engine running. To quickly cool down the passenger compartment, turn
temperature selector switch fully to the left to
position O. Turn temperature selector to maintain
desired temperature.
The air conditioning mode removes considerable
moisture from the air during operation in the cooling
mode. It is normal for water to drip on the ground
through ducts in the underbody.
Important!
This vehicle is equipped with an air conditioner system
that uses R–134a (HFC: hydrof luorocarbon) as a
refrigerant. Repairs should always be performed by a
qualified technician, and refrigerant should be collected
in a recovery system for recycling.
Note:
For the air flow-through system to function properly, the
air vents, located in the left and right side rear
passenger compartment trim panel covers, should be
ke pt un obst ru cte d .

224
Malfunction and indicator lamps
Te ch n ica l
data
Instruments
and controls Operation Driving
Instrument
cluster display Practical hints Car care Index
Low engine oil level warning lamp With the key in steering lock position 2, the
oil level warning lamp comes on and should
go out when the engine is running.
If the warning lamp does not go out after starting the
engine, or comes on with the engine running and at
operating temperature, the engine oil level has dropped
to approximately the minimum mark on the dipstick.
When this occurs, the warning lamp will first come on
intermittently and then stay on if the oil level drops
further.
If no oil leaks are noted, continue to drive to the nearest
service station where the engine oil should be topped to
the “full” mark on the dipstick with an approved oil.
The low engine oil level warning light should not be
ignored. Extended driving with the light illuminated
could result in serious engine damage that is not
covered by the Mercedes-Benz Limited Warranty.
In addition to the warning lamp, the engine oil level
should be periodically checked with the dipstick or via
the oil level indicator in the odometer display field, for
example during a fuel stop, or before a long trip (see
engine oil level indicator on page 89 and checking
engine oil on page 233). Low engine coolant level warning
When the coolant level warning lamp comes
on while driving, then the coolant level has
dropped below the required level, or the
coolant temperature is in the red zone. 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, see
page 234. If the engine temperature reaches the red
zone, move vehicle to an area which is in a safe distance
from the roadway and turn off the engine. Also see
coolant temperature gauge on page 81.
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 Light Truck Center as soon as possible.
Notes:
Do not drive without coolant in the cooling system. The
engine will overheat causing major engine damage.
Monitor the coolant temperature gauge while driving.

235
Engine compartment
Te ch n ica l
data
Instruments
and controls Operation Driving
Instrument
cluster display Practical hints
Car care Index
Adding coolant
If coolant has to be added, a 50 / 50 mixture of water and
MB anticorrosion / antifreeze should be added.
After adding coolant, close cap until you hear it click a
few times.
The drain plugs for the cooling system are located on
the left and right side of the engine block directly above
the engine mounts and at the bottom of the radiator.
Anticorrosion / antifreeze mixture, see page 297.
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.

293
Fuels, coolants, lubricants etc. - capacities
Te ch n ica l
data
Instruments
and controls Operation Driving
Instrument
cluster display Practical hints Car care Index
Brake system
(MB Brake fluid [DOT 4+]) approx. 0.9 US qt (0.8 l)
Windshield / headlamp washer system
(MB Windshield washer concentrate “S”
1) Vehicles without
headlamp cleaning
system
Vehicles with headlamp
cleaning system approx. 5.5 US qt (5.0 l)
approx. 8.0 US qt (7.6 l)
Cooling system
(MB Anticorrosion / antifreeze) approx. 12.7 US qt (12.0 l)
Fuel tank
including a reserve of
(Premium unleaded gasoline:
Posted Octane 91 (Avg. of 96 RON / 86 MON)) ML 320 / ML 430
ML 55 AMG approx. 19.2 US gal (73.0 l)
approx. 3.2 US gal (12.0 l)
approx. 24.5 US gal (93.0 l)
approx. 3.2 US gal (12.0 l)
Air conditioner system
(R-134a refrigerant and special
PA C l u b r i c a n t (Never R-12))
1 Use MB Windshield Washer Concentrate “S” and water for temperatures above freezing or MB Windshield Washer Concentrate “S” and
commercially available premixed windshield washer solvent / antifreeze for temperatures below freezing. Follow suggested mixing r atios, see
page 237.Fuels, coolants, lubricants etc. Model Capacity