2003 CHEVROLET C/K service

6-34
Rear Axle
When to Check and Change Lubricant
Refer to the Maintenance Schedule to determine how
often to check the lubricant and when to change it. See
ªScheduled Maintenance Servicesº in the Index.
How to Check Lubricant
To get an accurate reading, the vehicle should be on a
level surface.If the level is below the bottom of the filler plug hole,
you'll need to add some lubricant. Add enough lubricant
to raise the level to the bottom of the filler plug hole.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See ªRecommended Fluids and
Lubricantsº in the Index.
Rear Axle Shift Motor (Option)
When to Check and Change Fluid
If you have an optional air-shift two-speed, controlled
traction, or locking differential type rear axle, a good
time to check the fluid level in the axle shift motor is
when the rear axle lubricant is checked. Use refrigerant
oil (shift motor only).
How to Check Fluid
Remove the plug on the front plate of the axle shift
motor, add enough fluid to raise the level to the bottom
of the filler plug hole, then replace the plug.
What to Use
Refer to your Maintenance Schedule to determine what
kind of lubricant to use. See ªRecommended Fluids and
Lubricantsº in the Index.

6-38
Adding Coolant
If you need more coolant, add the proper DEX
-COOL

coolant mixture at the surge tank, but only when the
engine is cool.
CAUTION:
You can be burned if you spill coolant on hot
engine parts. Coolant contains ethylene glycol,
and it will burn if the engine parts are hot
enough. Don't spill coolant on a hot engine.
When replacing the pressure cap, make sure it is
hand
-tight.
Engine Coolant (Caterpillar

Diesel Engine)
If your vehicle has a Caterpillar diesel engine, see the
Caterpillar
Diesel Engine Operation & Maintenance
Manual provided with your vehicle to find out what to
add, also when and how to service your cooling system.
Surge Tank Pressure Cap
The surge tank pressure cap
is located in the engine
compartment, on the
driver's side of the vehicle.
The surge tank pressure cap must be tightly installed.
NOTICE:
Your surge tank pressure cap is a 15 psi (103kPa)
pressure
-type cap for use with medium duty
cooling systems only. It must be tightly installed
to prevent coolant loss and possible engine
damage from overheating.

6-39
Power Steering Fluid
See your Maintenance Schedule for when to check your
power steering fluid.
How To Check Power Steering Fluid
Check your power steering fluid only when the engine is
warm. If the engine isn't warm, you probably won't get
an accurate reading.
If the fluid level is
between the MIN and
MAX marks, you have
enough. If you need
fluid, add only enough
of the proper fluid to
bring it into view in
the sight glass.If your power steering fluid level is low, this can cause
the BRAKE or service brake soon warning lights to
come on. If either light remains on after you have added
power steering fluid to the proper level, then shut off the
engine for 10 seconds. This should reset the brake
warning lights. If one or both lights stay on though, see
ªHydraulic Brake Warning Lightsº in the Index.
What to Use
To determine what kind of fluid to use, see
ªRecommended Fluids and Lubricantsº in the Index.
NOTICE:
When adding power steering fluid or making a
complete fluid change, always use the proper
fluid. Failure to use the proper fluid can cause
leaks and damage hoses and seals.

6-47 Electric Air Compressor (If Equipped)
Your vehicle may be equipped with an electric air
compressor. This compressor is used to run options that
require pressurized air, such as an air horn, air seat,
exhaust restrictor or an exhaust brake.
This air compressor is used when vehicles are not
equipped with an air brake system.
The air supply for this
system must be maintained
by releasing the drain
valve to eject any moisture
that may have built up in
the system.
It is recommended that this system be drained on a
weekly basis.
Clutch Pedal Free Travel
If you have a manual transmission, your clutch will need
adjustment when pedal free travel gets down to about
1/4 inch (32 mm), as measured at the clutch pedal pad.
You should have 1 1/2 to 2 inches (38 to 51 mm) of
clutch pedal free travel. See ªMaintenance Scheduleº in
the Index for more information.
If your clutch ever needs service, be sure to use only
genuine GM clutch replacement parts.
Chassis Lubrication
Your Maintenance Schedule provides all of the required
chassis lubrication intervals and identifies proper
lubricants to use. Be sure to see your Maintenance
Schedule before performing any chassis lubrication
service. To determine location of chassis lubrication
items, use the following charts.

6-54
Other Service Items
Fuel Filter (Gasoline Engines)
The steel fuel filter is located near the engine
compartment on the driver's side of the vehicle.
See your Maintenance Schedule for recommended
service intervals.If your vehicle is equipped with the optional Davco
spin
-on type filter, it is located on the driver's side
frame rail.
Fuel Filter (Diesel Engines)
If you have a diesel engine, your fuel filter is located in
the engine compartment on the driver's side of the
vehicle, or along the driver's side frame rail. See ªFuel
Filter Replacementº earlier in this section for further
information.
Also see your Maintenance Schedule for recommended
service intervals.

6-58
Tires
Your new vehicle comes with high-quality tires made by
a leading tire manufacturer. If you ever have questions
about your tire warranty and where to obtain service, see
your General Motors Warranty booklet for details.
CAUTION:
Poorly maintained and improperly used tires are
dangerous.

Overloading your tires can cause
overheating as a result of too much friction.
You could have an air
-out and a serious
accident. See ªLoading Your Vehicleº in
the Index.
CAUTION: (Continued)
CAUTION: (Continued)

Underinflated tires pose the same danger as
overloaded tires. The resulting accident
could cause serious injury. Check all tires
frequently to maintain the recommended
pressure. Tire pressure should be checked
when your tires are cold.

Overinflated tires are more likely to be
cut, punctured or broken by a sudden
impact
-- such as when you hit a pothole.
Keep tires at the recommended pressure.

Worn, old tires can cause accidents. If your
tread is badly worn, or if your tires have
been damaged, replace them.

6-60
When to Check
Check your tires once a month or more. Also, check the
tire pressure of the spare tire (if equipped).
How to Check
Use a good quality pocket
-type gage to check tire
pressure. You can't tell if your tires are properly inflated
simply by looking at them. Radial tires may look
properly inflated even when they're underinflated.
Be sure to put the valve caps back on the valve stems.
They help prevent leaks by keeping out dirt and
moisture.
Rims and Wheels
Rims and wheels are stamped with a maximum load
and cold inflation rating. Be sure you don't exceed
these limits.
Dual Tire Operation
When the vehicle is new, check the wheel nut tightness
on all wheels with a torque wrench after your first
100 miles (160 km) and then 1,000 miles (1 600 km)
after that. Whenever a wheel, wheel bolt or wheel nut is
removed or serviced, repeat the 100 miles (160 km), and
then 1,000 mile (1 600 km) wheel nut tightness check.
See ªTightening the Wheel Nutsº later in this section
for proper torque values and wheel nut tightening
information.
CAUTION:
If you operate your vehicle with a tire that is
badly underinflated, the tire can overheat. An
overheated tire can lose air suddenly or catch
fire. You or others could be injured. Be sure all
tires (including the spare, if any) are properly
inflated.
See ªTiresº and ªInflation -- Tire Pressureº in the Index
for more information on proper tire inflation.

6-65
CAUTION:
Rust or dirt on a wheel, or on the parts to which
it is fastened, can make the wheel nuts become
loose after a time. The wheel could come off and
cause a crash. When you change a wheel, remove
any rust or dirt from the places where the wheel
attaches to the vehicle. In an emergency, you can
use a cloth or paper towel to do this; but be sure
to use a scraper or wire brush later, if you need
to, to get all the rust or dirt off.
How Often to Check
Wheel tightness is so important you should have a
technician check nut tightness on all wheels with a
torque wrench after your first 100 miles (160 km), and
then 1,000 miles (1 600 km) after that. Be sure to repeat
this service whenever you have a tire removed or
serviced. See ªMaintenance Scheduleº in the Index for
further information.