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Vehicle Care 237
may be lost and damage to the
engine may result from overheating.
The radiator pressure cap should be
checked periodically for proper
operation. If a replacement is
required, a genuine GM part is
recommended.
Engine Overheating
When the Engine Overheats
The engine cooling system may
overheat if the engine coolant level
is too low, if there is a sudden loss
of engine coolant (such as radiator
hose failure), or if other problems
occur. It may also temporarily
overheat during severe operating
conditions such as:
.Climbing a long hill on a hot day.
. Stopping after high-speed
driving.
. Idling for long periods in traffic.
If engine power drops and the
needle on the engine coolant
temperature gauge goes up above
the upper limit of the safety zone
and enters the "H" zone, the engine
is overheating. The engine overheat warning light will come on and the
warning buzzer will sound. Either
steam or boiling engine coolant will
squirt out of the radiator. The
vehicle will also have an
“OVER
HEAT” message displayed. Take the
following corrective actions
immediately.
{Warning
To help avoid being burned:
Do not tilt the cab or open the
engine access cover if you see or
hear steam or engine coolant
escaping from the engine
compartment. Wait until no steam
or engine coolant can be seen or
heard before tilting the cab or
opening the engine cover.
Do not remove the radiator cap or
engine coolant reserve tank cap if
the engine coolant in the tank is
boiling. Also do not remove the
radiator cap while the engine and
radiator are still hot. Scalding fluid
(Continued)
Warning (Continued)
and steam can be blown out
under pressure if either cap is
taken off too soon.
You and others could be seriously
injured.
If Steam Is Coming from the
Engine Compartment
{Warning
If the engine coolant temperature
gauge shows an overheat
condition or you have other
reasons to suspect the engine
may be overheating, continued
operation of the engine (other
than as described here) even for
a short period of time may cause
a fire and the result in personal
injury and severe vehicle
damage. Take immediate action
as outlined.
You and others could be seriously
injured.
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Vehicle Care 239
Warning (Continued)
refilling, and replacement of
coolant only when its temperature
has cooled.
When removing the radiator cap
and reserve tank cap, use a thick
cloth to cover the cap and turn it
little by little.
You and others could be seriously
injured.
4. If no steam or engine coolant can be seen or heard from the
engine compartment:
.Tilt the cab or open the
engine access cover.
‐If the engine coolant is
boiling, wait until it stops
before proceeding.
‐ Look at the see-through
reserve tank. The
engine coolant level
should be between the
"MAX" and "MIN" lines
on the reserve tank. ‐
If necessary, pour
engine coolant (See
Engine Coolant 0231
for the proper coolant
and water mixture) into
the reserve tank only,
not directly into the
radiator. Also, do not
check engine coolant
level at the radiator.
. Make sure the fan belts are
not broken, or off the
pulleys, and that the fan
turns when the engine is
started. Make sure the fan
blade and pulleys are not
broken.
. Check the radiator hoses
and connections, heater
hoses and connections,
radiator, water pump, EGR
cooler, and SCR system
and hoses for leakage.
If you do not find a leak or
other problem, carefully add
engine coolant to the
reserve tank. If the engine coolant level in
the reserve tank is at the
correct level but there is still
an indication on the
instrument panel of an
overheat condition:
You must let the engine
cool first. You may then add
engine coolant directly to
the radiator. See
“Adding
Engine Coolant” under
Engine Coolant 0231.
5. Inspect to see if there is any dirt, etc. attached to the front
surface of the radiator. Also,
inspect to see if there is
anything blocking the core.
If there is anything attached,
clean and remove it.
6. After the inspection, regardless of the vehicle condition, please
contact the nearest dealer.
Once the engine coolant
temperature gauge no longer
signals an overheat condition, you
can resume driving at a reduced
speed. Return to normal driving
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240 Vehicle Care
after about 10 minutes if the gauge
pointer does not again show an
overheat condition.
When tap water only has been used
for engine coolant in an emergency,
change the engine coolant as soon
as possible.
Engine damage may be caused if
an overheating engine is suddenly
refilled with water. Instead, refill
slowly.
Power Steering Fluid
The power steering fluid level must
be checked and it must be changed
according to the Maintenance
Schedule. SeeMaintenance
Schedule 0303.
When replenishing power steering
fluid or flushing the power steering
system, always use ATF
(Dexron
®-VI). Failure to use the
proper fluid may damage the power
steering system seals and hoses,
leading to fluid leakage.
Checking the Power Steering
Fluid Level
The fluid level is correct if it is
between the “MAX”and“MIN” lines
on the reserve tank. If the level is
lower that the “MIN”line, add fluid
up to the “MAX”line.
The reserve tank is located at the
rear of the engine compartment on
the right. When you have finished
checking the fluid level, securely
install the cap and cover.
When you have finished checking
the fluid level, securely install
the cap.
The fluid level is correct if it is
between the "MAX" and "MIN" lines
on the oil dipstick. If the level is
lower than the "MIN" line, add fluid
up to the "MAX" line.
{Warning
Before adding fluid, clean the
area around the cap and pour
fluid from a clean jug or filler.
Foreign matter getting in the tank
may cause power steering system
failure. (Continued)
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282 Vehicle Care
Danger (Continued)
.Note that taking off and
mounting tires on wheels
requires proper tools, safety
equipment and special
training. A person can be
severely injured or killed
and damage can result from
using the wrong service
methods. Truck tires and
wheels should be serviced
only by trained people using
the proper equipment.
. Never add air to your tires
unless an accurate pressure
gauge is also used. When
putting air in a tire on the
vehicle, stand to the side
and use a clip-on chuck and
hose extension. In choosing
the right tire pressure, be
careful not to exceed the
maximum pressure
capability shown on the tire;
see the tire pressure charts
in this manual.
(Continued)
Danger (Continued)
.Tire mounting or repair can
result in serious personal
injury or death, if not
performed correctly. This
section has detailed
instructions for proper wheel
and tire replacement, so be
sure to read and follow
them. Truck fleet owners
and operators: You can get
written instructions on truck
tire demounting, repair and
mounting from Rubber
Manufacturers Association
(RMA), 1400 K Street N.W.,
Washington, D.C. 20005,
and also from many tire
stores.
Wheel Nut Torque
{Warning
Never use oil or grease on studs
or nuts. Use the torque specified
for the type of wheels on the (Continued)
Warning (Continued)
vehicle. Snug all wheel nuts and
then tighten to the specified
torque in the numerical sequence
shown. Improperly tightened
wheel nuts could eventually allow
the wheel to come off while the
vehicle is moving, possibly
causing loss of control and
personal injury and property
damage.
When the vehicle, wheel or
fasteners are new, have a
technician tighten wheel stud nuts
and rim clamp nuts with a torque
wrench at 1 040 km (650 mi). This is
necessary because the clamping
system used on the wheels must
seat before the fastener will hold a
uniform clamp load and remain fully
tightened. Also have a technician
tighten wheel stud nuts and rim
clamp nuts with a torque wrench
after installing any wheel.
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294 Vehicle Care
conditions such as high-pressure
car washers may cause water to
enter inside the vehicle. If the
vehicle is operated with foreign
material adhering to the exterior,
this material may react chemically
with paint, resulting in staining,
discoloration, rusting or corrosion of
components. Also, the material may
become trapped within mechanical
components, adversely affecting
their functions or forming an
aerodynamic resistance. In the
following cases, therefore, the
vehicle must be washed and all
foreign matter removed.
.When soot, iron powder, dead
bugs, bird droppings, tree sap or
oily matter from coal tar and
smoke has adhered to painted
surfaces.
. When the vehicle has been
driven in coastal areas.
. When the vehicle has been
driven on roads where road
chemicals have been applied.
. When a large amount of mud or
dirt has adhered to the exterior. To wash the vehicle:
1. Fully turn on the tap, and wash out the undercarriage and
suspension.
2. Close all openings and wash the cab and cargo body panels
using a neutral detergent.
3. Clean wheels and tires using a brush and detergent.
4. After washing away all remaining detergent, use a
shammy or other clean cloth to
fully remove all moisture and
water droplets.
{Warning
Follow the manufacturer's advice
whenever cleaning agents or
other chemicals are used, inside
or outside the vehicle. Some
cleaners may be poisonous or
flammable, and improper use may
cause personal injury or damage.
When cleaning the inside or
outside of the vehicle, do not use
volatile cleaning solvents, such as
(Continued)
Warning (Continued)
acetone, lacquer thinners, enamel
reducers, nail polish removers; or
such cleaning materials as
laundry soaps, bleaches or
reducing agents, except as noted
in the following fabric cleaning
advice on stain removal.
Never use carbon tetrachloride,
gasoline, benzene or naphtha for
any cleaning purpose. Open all
vehicle doors for ventilation when
ANY cleaning agents or other
chemicals are used in the interior.
Overexposure to some vapors
may result in a health problem
that is more likely to occur in
small, unventilated spaces.
You and others could be seriously
injured.
Do not apply water directly in order
to clean the cab interior. Failure to
observe this precaution can result in
malfunction or breakdown of
electronic control units and electrical
components, or in rusting of the cab
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300 Vehicle Care
cleaning products contain these
compounds. Be sure to read
cleaning product labels carefully.
Air fresheners (liquid, solid, gel or
plate types) must not come into
direct contact with, or spill onto,
interior components such as the air
conditioning or audio system.
Compounds contained in these
products can cause discoloration,
staining or peeling of paint.
Glass cleaners that contain these
compounds must not be used to
clean the inside of the windshield or
window glass. To clean the glass,
wipe it using a cloth wet with warm
or cold water.
To avoid possible permanent
discoloration of light colored seats,
Do not let materials with non-fast
colors come into contact with seat
trim materials until these materials
are totally dry. This includes certain
types of casual clothing, such as
colored denims, corduroys, leathers
and suedes; also decorative paper,
With the use of modern trim
materials, it is very important that
you use proper cleaning techniquesand cleaners. Failing to do this on
the first cleaning may result in water
spots, spot rings or setting of stains
or soilage - all of which are more
difficult to remove in a second
cleaning.
Dust and loose dirt that collect on
interior fabric should be removed
often with a vacuum cleaner or soft
bristle brush. Wipe vinyl or leather
trim regularly with a clean, damp
cloth. Normal trim soils, spots or
stains can be cleaned with these
cleaners.
Remember these basic steps before
cleaning:
.
Remove stains as quickly as
possible before they
become "set".
. Use a clean cloth or sponge,
and change to a clean area
often. A soft brush maybe used
if stains persist.
. Use solvent-type cleaners only
in a well ventilated area: also, do
not saturate the stained area. .
If a ring forms after spot
cleaning, clean the entire area
immediately.
. Follow specific instructions on
cleaner labels.
General Cleaning of Soiled or
Water Spotted Fabric Type
Trim with Foam Type Cleaner
Vacuum the area thoroughly to
remove any loose dirt.
Always clean a whole trim panel or
section. Mask surrounding trim
along stitch or welt lines.
Use suds on a clean sponge. Do
not brush wet suede. Do not
saturate the material or rub it
harshly. Immediately after cleaning,
remove suds with a sponge and
rinse with a clean wet sponge. Wipe
off remaining residue with a slightly
damp absorbent towel or cloth.
Important —Immediately after
wiping, force-dry the fabric with an
air hose. A heat dryer or heat lamp
may be used. Use caution with a
heat dryer or lamp to help prevent
damage.
Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
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Service and Maintenance 305
Preventive Maintenance
As any mechanical device operates,
a certain amount of wear occurs.
The amount of wear depends on
certain variables–type and method
of operation and the schedule of
maintenance. These variables may
be emphasized as critical to
malfunction but each is dependent
upon the other. For example, if a
vehicle is repeatedly overloaded,
driven at excessive speed or
improperly shifted, no schedule of
maintenance can prevent
malfunction. Also, if a preventive
maintenance schedule is not
followed, or is improperly carried
out, no amount of correct vehicle
operation will prevent malfunction.
If vehicle application, operation and
preventive maintenance schedules
and procedures are followed and
properly carried out, the life of the
vehicle will be greatly extended. For example, regular attention to the
engine oil is essential. The oil level
must be periodically checked and oil
added whenever needed. Also, the
oil should be changed at the
intervals specified with the proper
quality and viscosity of oil. If your
engine should run excessively low
on oil or if the oil has lost its
lubricating qualities because of old
age, serious engine damage could
occur.
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Service and Maintenance 313
rocker shaft bracket nuts before
checking and adjusting valve
clearance.
Check and adjust valve clearance
every 80 000 km (50,000 miles) or
12 months whichever occurs first.
3. Engine Oil and Oil Filter :
Change at interval noted below
depending upon driving conditions.
•Normal Service —Change every
16 000 km (10,000 miles) or
12 months whichever occurs first.
• Severe Service —Change every
8 000 km (5,000 miles) or 3 months
if you often drive under one or more
of these conditions: (a) driving in
dusty areas, (b) frequent idling or
idling for long periods, (c) driving
6 km (4 miles) or less in freezing
weather, or other short trips in cold
weather, where the engine does not
thoroughly warm up.
Change oil and filter as soon as you
can after driving in a dust storm.
When recommended oil is used, it
conforms to this maintenance
schedule. (Recommended oil: CK-4
(API designations)) 4. Fuel Filter :
Replace the fuel
filter every 24 000 km (15,000 miles)
or more frequently if clogged or
replace when the fuel filter indicator
light comes on (if equipped).
5. Pre-Fuel Filter/Water
separator : Replace the fuel filter
every 24 000 km (15,000 miles) or
more frequently if clogged or
replace when the fuel filter indicator
light comes on (if equipped).
6. Air Cleaner Filter : The level of
dirt in the air cleaner element can
be checked against the indicator.
Replace the air cleaner filter when
the Driver Information Center (DIC)
shows "CHECK AIR FILTER".
7. Damage to Air Intake Ducts and
Hoses : Check for damage of air
intake ducts and hoses and that
those are correctly installed every
24 000 km (15,000 miles) or
12 months. Replace or adjust those
if necessary. 8. Drive Belts :
Check belt driving
the fan, alternator or A/C
compressor every 16 000 km
(10,000 miles). Look for cracks,
fraying, wear, and proper tension.
9. Engine Bolt Torques : Loosened
bolts result in lower engine output.
Check and adjust manifold
mounting, and injectors to correct
torque every 80 000 km
(50,000 miles).
10. Rotate Tires : To equalize wear,
rotate tires and adjust tire pressures
every 10 400 km (6,500 miles). See
Tire Rotation 0284.
11. Engine Cooling System : At
12 months or 16 000 km
(10,000 miles) intervals, wash
radiator cap and filler neck with
clean water, pressure test system
and radiator cap for proper pressure
holding capacity, tighten hose
clamps and inspect condition of all
cooling and heater hoses. Replace
hoses if cracked, swollen or
otherwise deteriorated. Have the
hoses replaced by your authorized
dealer.