brakes MERCEDES-BENZ ML320 1997 Complete Manual PDF

194 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.If the parking brake is released and the
brake warning lamp in the instrument clus-
ter stays on and there is no audible warn-
ing (EBP), 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 res-
ervoir.
Have the brake system inspected immedi-
ately. Contact your authorized
Mercedes-Benz Light Truck Center.
All checks and service work on the brake
system should be carried out by qualified
technicians only. Contact your authorized
Mercedes-Benz Light Truck 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 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.
!Be very careful not to endanger other
road users when you apply the brakes.
Refer to the description of the Brake
Assist System (BAS) (
page 78).

195 Operation
Driving instructions
Install only brake pads and brake fluid
recommended by Mercedes-Benz.
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 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 oper-
ating temperature has been reached.
When starting off on a slippery surface, do
not allow a drive wheel to spin for an ex-
tended period with the ESP switched off.
Doing so may cause serious damage to the
drivetrain which is not covered by the
Mercedes-Benz Limited Warranty.
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.

197 Operation
Driving instructions
The tread wear indicator appears as a solid
band across the tread.
Specified tire pressures must be main-
tained. This applies particularly if the tires
are subjected to high loads (e.g. high
speeds, heavy loads, high ambient temper-
atures).
Hydroplaning
Depending on the depth of the water on
the road, hydroplaning may occur even at
low speeds and with new tires. Reduce ve-
hicle speed, avoid track grooves in the
road and apply brakes cautiously in the
rain.Tire traction
The safe speed on a wet, snow covered or
icy road is always lower than on a dry road.You should pay particular attention to the
condition of the road whenever the outside
temperatures are close to the freezing
point.
Mercedes-Benz recommends M+S rated
radial-ply tires with a minimum tread depth
of approximately
1/6in (4 mm) on all four
wheels for the winter season to ensure
normal balanced handling characteristics.
On packed snow, they can reduce your
stopping distance as compared with sum-
mer tires.
Stopping distance, however, is still consid-
erably greater than when the road is not
covered with snow or ice. Exercise appro-
priate caution.
Warning!
G
Although the applicable federal motor vehi-
cle safety laws consider a tire to be worn
when the tread wear indicators (TWI) be-
come visible at approximately
1/16in
(1 .6 mm ), w e re c om men d th a t y o u do n o t a l-
low your tires to wear down to that level. As
tread depth approaches
1/8in (3 mm), the
adhesion properties on a wet road are
sharply reduced.
Depending upon the weather and / or road
surface (conditions), the tire traction varies
widely.
Warning!
G
Do not drive with a flat tire. A flat tire affects
the ability to steer or brake the vehicle. You
may lose control of the vehicle. Continued
driving with a flat tire or driving at high
speed with a flat tire will cause excessive
heat build-up and possibly a fire.
Warning!
G
If ice has formed on the road, tire traction
will be substantially reduced. Under such
weather conditions, drive, steer and brake
with extreme caution.

200 OperationDriving instructionsStanding water
Off-road driving
Read this chapter carefully before you be-
gin off-road travel.
Familiarize yourself with the vehicle char-
acteristics and gear changing before you
attempt any difficult terrain off-road driv-
ing. We recommend that you start out with
easy off-road travel.
!Do not drive through flooded areas or
water of unknown depth. Before driving
through water, determine its depth.
Never accelerate before driving into
water. The bow wave could force water
into the engine and auxiliary equip-
ment, thus damaging them.
If you must drive through standing wa-
ter, drive slowly to prevent water from
entering the passenger compartment
or the engine compartment. Water in
these areas could cause damage to
electrical components or wiring of the
engine or transmission, or could result
in water being ingested by the engine
through the air intake, causing severe
internal engine damage. Any such dam-
age is not covered by the
Mercedes-Benz Limited Warranty.
Warning!
G
Drive slowly in unknown terrain. This will
make it easier to recognize unexpected ob-
stacles and avoid damage to the vehicle.
To help avoid the vehicle rolling over, never
turn it around on steep inclines. If the vehi-
cle cannot complete the attempted climb,
back it down in reverse gear.
Do not drive along the side of a slope (dan-
ger of vehicle rollover). The vehicle might
otherwise rollover. If in doing so the vehicle
begins to show a tendency to roll, immedi-
ately steer into a line of gravity (straight up
or downhill).
Never let the vehicle roll backwards in idle.
You may lose control of the vehicle if you
use only the service brake.
Warning!
G
Sand, dirt, mud and other material having
friction property can cause exceptional wear
and tear as well as brake failure.
Have the brakes checked for dirt build-up
and cleaned. There is otherwise a risk that
full braking power may not be available in an
emergency.

202 OperationDriving instructionsRims

Dented or bent rims can cause tire
pressure loss and damage the tire
beads. For this reason, check and, if
necessary, change rims before driving
off-road.
Vehicle tool kit


Check if the vehicle jack is functional.


In all cases take the vehicle tool kit, a
strong tow rope, a shovel and a small
plank (to put under the vehicle jack on
sandy soil) with you.
Driving in steep terrain
Slope angle1 25°
226°

Switch to LOW RANGE mode before
starting to drive up or down steep in-
clines (
page 125).


Driving on embankments, slopes and
other steep inclines should only be
done straight up or downhill, i.e. in the
line of gravity. Maximum vehicle climb-
ing ability is a 60% grade.


Do not drive along the side of a slope
(danger of vehicle rollover). If in doing
so, the vehicle begins to show a ten-
dency to roll, immediately steer into a
line of gravity (straight up or downhill).


To help avoid the vehicle rolling over,
never turn it around on steep inclines.
If the vehicle cannot complete the at-
tempted climb, back it down in reverse
gear.


Utilize the engine’s braking power
when descending a slope, observe the
engine speed (do not overview the en-
gine). Apply the service brake as need-
ed.


Check the brakes after a lengthy down-
grade drive.
Traction in steep terrain


Be easy on the accelerator and watch
for continuous wheel traction when
driving in steep terrain.
The 4-ETS helps greatly when starting
out on a steep incline when the front
wheels have then the tendency to slip
due to the weight shifting away the
front axle.iAvoid excessive engine speeds – drive
with moderate engine speeds
(max. 3000 RPM).
Select gear range2 or1 on the auto-
matic transmission (
page 121).

204 OperationDriving instructions

Switch off the exterior lamps as well as
the climate control.


Select gear range1 on the automatic
transmission (
page 121).


Enter the water only at a shallow spot,
driving at walking speed.


Do not stop vehicle while immersed in
water, and do not shut off the engine.
There is a very high level of driving re-
sistance in water. The surface is slip-
pery and may not be firm, making
pulling away in water difficult and dan-
gerous.


Clean mud off the tire tread after driv-
ing through water.


To dry the brakes, apply pressure to the
brake pedal several times after leaving
the water.
Crossing obstacles
!Never accelerate before driving into
the water. The bow wave could force
water into the engine and auxiliary
equipment, thus damaging them.
!Obstacles can damage the vehicle
undercarriage or suspension compo-
nents. If possible use the assistance of
a second person outside the vehicle to
scout the path you intend to take and
check for adequate ground clearance
when you cross obstacles with your ve-
hicle. The person assisting you outside
the vehicle should always be a safe dis-
tance away from the vehicle and posi-
tioned so that he or she cannot get hurt
in case of any unexpected vehicle
movement.
After off-road driving or crossing obsta-
cles, inspect vehicle for any damage,
especially vehicle undercarriage and
suspension components. Failure to do
so can adversely affect the vehicle's fu-
ture performance, including increased
chance of an accident.

206 OperationDriving instructionsOff-road driving increases strain on the
vehicle.
We recommend that you inspect the vehi-
cle for possible damage after each off-road
trip. Recognizing any damage and a subse-
quent timely repair reduces the chance of
a possible breakdown or accident later on.
Proceed as follows:

Switch off the LOW RANGE mode
(page 125).


Remove excessive dirt from tires,
wheels, wheel housings, and under-
body.
For instance, after driving in mud, clean
the radiator, chassis, engine, brakes,
and wheels from extreme dirt using a
strong jet of water.


Inspect frame, oil pan, brake hoses,
etc., as well as vehicle underbody for
possible damage.


Check tires for possible damage, clean
all exterior lamps, and conduct a brake
test.


Check for brush or branches caught in
the undercarriage.
They could increase the possibility of a
fire, as well as cut fuel and / or brake
lines, puncture rubber bellows of the
axles or drive shafts.


After continued operation in mud,
sand, water or other dirty conditions
clean the brake discs, wheels, brake
pads and check and clean axle joints.
Trailer towingWarning!
G
Failure to use proper equipment and driving
technique can result in a loss of vehicle con-
trol when towing a trailer.
Improper towing or failure to follow the in-
structions contained in this guide can result
in serious injury. Follow the guidelines be-
low carefully to assure safe trailer operation.
Ask your authorized Mercedes-Benz Light
Truck Center should you require an explana-
tion of information contained in this guide.

208 OperationDriving instructionsLoading a trailer

When loading a trailer, you should ob-
serve that neither the permissible GTW,
nor the GVWR are exceeded.
Maximum permissible values are listed
on the safety compliance certification
labels for the vehicle and for the trailer
to be towed.
The lowest value listed must be select-
ed when determining how the vehicle
and trailer are loaded.


The tongue weight at the hitch ball
must be added to the GVW to prevent
exceeding your Mercedes-Benz tow
vehicle’s rear GAWR.Checking weights of vehicle and trailer


To assure that the tow vehicle and trail-
er are in compliance with the maximum
permissible weight limits have the load-
ed rig (tow vehicle including driver, pas-
sengers and cargo, trailer fully loaded)
weighed on a commercial scale.


Check the vehicle’s front and rear
Gross Axle Weight (GAW), the GTW and
TW.
The values as measured must not be
exceeded, according to the weight list-
ed under “Vehicle and trailer weight
and ratings”.Attaching a trailer
Observe maximum permitted trailer
dimensions (width and length).
Most states and all Canadian provinces
require


safety chains between your tow vehicle
and the trailer.
The chains should be crisscrossed un-
der the trailer tongue. They must be at-
tached to the hitch receiver, and not to
the vehicle’s bumper or axle.
Be sure to leave enough slack in the
chains to permit turning corners.


a separate brake system at various
trailer weights.


a break-away switch on trailers with a
separate brake system.
The switch activates the trailer brakes
in the possible event that the trailer
might separate from the tow vehicle.
iWe recommend loading the trailer in
such a manner that it has a tongue
weight (TW) between 10% and 15% of
the GTW.

209 Operation
Driving instructions
Towing a trailer
There are many different laws, including
speed limit restrictions, having to do with
trailer towing. Make sure your rig will be le-
gal, not only for where you reside, but also
for where you will be driving. A good
source for this information can be the po-
lice or local authorities.
Note the following points, when driving
with the trailer:

In order to gain skill and an under-
standing of the vehicle’s behavior, you
should practice turning, stopping and
backing up in an area which is free from
traffic.


Before you start driving check the

trailer hitch


break-away switch


safety chains


electrical connections


lighting and tiresAdjust the mirrors to permit unobstructed
view beyond rear of trailer.


If the trailer has electric brakes, start
your vehicle and trailer moving slowly,
and then apply only the trailer brake
controller by hand to be sure the
brakes are working properly.


Always secure items in the trailer to
prevent load shifts while driving.


When towing a trailer, check occasion-
ally to be sure that the load is secure,
and that lighting and trailer brakes (if
so equipped) are functioning properly.


Take into consideration that when tow-
ing a trailer, the handling characteris-
tics are different and less stable from
those when operating the vehicle with-
out a trailer.
It is important to avoid sudden maneu-
vers.
!Do not connect a trailer brake system
(if trailer is so equipped) directly to the
vehicle’s hydraulic brake system, as
your vehicle is equipped with antilock
brakes. If you do, neither the vehicle’s
brakes nor the trailer’s brakes will func-
tion properly.iThe provided vehicle electrical wiring
harness for trailer towing has a brake
signal wire (color orange) for hook-up
to a brake controller.
You should consider using a trailer
sway control system. For further infor-
mation see your authorized
Mercedes-Benz Light Truck Center.

210 OperationDriving instructions

The vehicle and trailer combination is
heavier, and therefore is limited in ac-
celeration and climbing ability, and re-
quires longer stopping distances.
I t i s m o r e p r o n e t o r e a c t i n g t o s i d e w i n d
gusts, and requires more sensitive
steering input.


If possible, do not brake abruptly, but
rather engage the brake slightly at first
to permit the trailer to activate its
brake. Then increase the braking force.


If the transmission hunts between
gears on inclines, manually shift to a
lower gear (select 4, 3, 2 or 1).
A lower gear and reduction of speed re-
duces the chance of engine overload-
ing and / or overheating.


On very steep inclines, not manageable
with gear selector lever in position1,
switch transfer case to LOW RANGE
mode (
page 125).


When going down a long hill, shift into
a lower gear and use the engine’s brak-
ing effect.
Avoid riding the brakes, thus overheat-
ing the vehicle and trailer brakes.


If the engine coolant rises to an ex-
tremely high temperature (coolant tem-
perature needle approaching the red
zone) when the air conditioning is on,
turn off the air conditioning system.
Engine coolant heat can be additionally
vented by opening the windows,
switching the climate control fan speed
to high and setting the temperature
control to the maximum hot position.


Extreme care must be exercised since
your vehicle with a trailer will require
additional passing distance ahead than
when driving without a trailer.
Because your vehicle and trailer is
longer than your vehicle alone, you will
also need to go much farther ahead of
the passed vehicle before you can re-
turn to your lane.
!If the trailer should begin to sway, re-
duce the vehicle’s speed and use the
brake controller by hand to straighten
out the vehicle and trailer.
In no case should you attempt to
straighten out the tow vehicle and trail-
er by increasing the speed or overstee-
ring and stepping on the brakes.