service interval CHEVROLET C/K 2003 Owners Manual

6-32
Automatic Transmission Fluid
When to Check
A good time to have it checked is when the engine oil is
checked. See your Allison Automatic Transmission
Operator's Manual to find out when to change your
transmission fluid and filters.
How to Check and What to Use
The Allison Automatic Transmission Operator's Manual
that came with the vehicle shows how to check the
automatic transmission fluid and what fluid to use.
Automatic Transmission External Filter
Your automatic transmission filter requires periodic
replacement.
Consult the Allison Automatic Transmission
Operator's Manual that came with the vehicle for
proper change intervals.
Manual Transmission Fluid
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.
Refer to the Maintenance Schedule to determine what
kind of fluid to use. See ªRecommended Fluids and
Lubricantsº in the Index.
When to Check
A good time to have it checked is when the engine oil is
checked. See your Maintenance Schedule to find out
when to change your transmission fluid.

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.

7-5
Scheduled Maintenance
The services shown in this schedule up to 100,000 miles
(166 000 km) should be repeated after 100,000 miles
(166 000 km) at the same intervals for the life of
this vehicle. The services shown after 100,000 miles
(166 000 km) should be repeated at the same miles (km)
after those intervals for the life of this vehicle.
Gasoline engine vehicles have a computer that lets you
know when to change your engine oil. This is not based
on mileage, but on engine revolutions and engine
operating temperature. When the computer has
calculated that the oil needs changing, the GM Oil Life
System will indicate that a change is necessary.
The ªFootnotesº at the end of this Maintenance
Schedule further explain maintenance services.
See ªScheduled Maintenance Supplementsº earlier in
this section.
100 Miles (160 km)

Wheel stud nut service. (46)
1,000 Miles (1 600 km)

Wheel stud nut service. (46)

Rear axle air shift motor service.(11)

L18/LB7 Engines Only: Clutch pedal free
travel service. (10)
7,500 Miles (12 000 km)

Gasoline Engine Only: Check Oil Life System.
If engine oil and filter are changed, reset system.
See ªEngine Oilº in the Index. (3)(9)

Check fluid levels (or every 3 months, whichever
occurs first). (1)(6)

Chassis lubrication service (or every 6 months,
whichever occurs first). (12)

Wheels and tires service. (15)

Parking brake service (or every 6 months, whichever
occurs first). (8)

L18/LB7 Engines Only: Clutch pedal free
travel service. (10)
10,000 Miles (16 000 km)

DURAMAX Diesel Only: Change engine oil
and filter (or every 12 months, whichever
occurs first). (2)(3)

7-16
Footnotes

= The U.S. Environmental Protection Agency or the
California Air Resources Board has determined that the
failure to perform this maintenance item will not nullify
the emission warranty or limit recall liability prior to the
completion of the vehicle's useful life. We, however,
urge that all recommended maintenance services be
performed at the indicated intervals and the maintenance
be recorded.
(1) = If your vehicle has an Allison automatic
transmission, your GM owner's manual is supplemented
by an Allison Transmission Operator's Manual. Always
refer to these manuals for related maintenance services.
(2) = Refer to the Caterpillar Diesel Engine Operation
and Maintenance Manual for oil recommendations and
change intervals.
(3) = An Emission Control Service.
(4) = A Noise Emission Control Device.
(5) = Applies only to vehicles sold in the United States.(6) = Check fluid level in brake master cylinder, power
steering pump, axle, transmission and hydraulic spring
parking brake pump (if equipped). A low fluid level in
the brake master cylinder can indicate worn brake
linings and should be checked accordingly.
(7) = Inspect brake lines and hoses for proper hook
-up,
binding, leaks, cracks, chafing, etc. Inspect disc brake
pads for wear and rotors for surface condition. Inspect
caliper assemblies. Check brake pedal for excessive free
play or travel (or every 6 months, whichever occurs first)
and have serviced if needed. Check brakes more often if
driving habits and conditions result in frequent braking.
(8) = Inspect parking brake drum and linings for wear or
cracks and check linkage and adjustment.
(9) = This vehicle has the GM Oil Life System. This
system will show you when to change the engine oil and
filter
-- usually between 3,000 miles (5 000 km) and
7,500 miles (12 000 km) since your last oil change.
Under severe conditions, the indicator may come on
before 3,000 miles (5 000 km). Never drive your vehicle
more than 7,500 miles (12 000 km) or 12 months
without an oil and filter change.
Remember to reset the Oil Life System whenever the oil
is changed. For more information, see ªChange Oil
Lightº in the Index.

7-17
(10) = Check clutch pedal for free travel. Press pedal
by hand until resistance is felt. Free travel should be
maintained at 1.5 to 2 inches (38 to 51 mm) measured
at the clutch pedal pad. Make checks at 1,000 miles
(1 600 km) and then at every 7,500 mile (12 000 km)
interval thereafter.
(11) = Inspect rear axle air shift motor for fluid leaks.
Remove plug to check fluid level. Inspect air lines and
hoses for proper hook
-up, binding, leaks, etc. Inspect at
3,000 miles (5 000 km) and 22,500 miles (36 000 km)
and then every 22,500 miles (36 000 km) thereafter.
(12) = Chassis Lubrication Service: Lubricate all grease
fittings in front suspension, front axle and steering
linkage. DO NOT lubricate kingpin bushings with air
pressure equipment; instead, use a hand grease gun to
ensure complete purge and eliminate sealer cap
distortion. Lubricate transmission and shift linkage,
hood latches and hood hinges, parking brake lever pivot,
clevis pins and linkage, disc brake caliper rails, clutch
linkage and release bearing (if equipped), bearing pads,
propshaft universal joints, brake camshaft bracket, slack
adjusters, pedal shaft, clutch cross shaft and clutch pedal
springs. Lubricate suspension, axle and steering linkage
more often when operating under dusty or muddy
conditions and in excessive off
-road use.(13) = Check steering system:

Look for damaged, loose or missing parts. Also look
for parts showing signs of wear or lack of lubrication.
Replace parts as needed. Also check steering gear
mounting bolts, pitman arm nut, gear housing upper
cover and side cover attaching bolts, steering column
mounting bolts and cardan joint clamp bolts; tighten
if necessary. (See service manual.)

Inspect power steering hoses, tubes and fittings for
leaks. Hoses and lines must not be twisted, kinked or
tightly bent. Make sure clips, clamps, supporting
tubes and hoses are in place and properly secured.

Check steering gear for leakage around pitman shaft
and housing. If leakage is evident (lubricant oozing
out, not just oily film), leak should be corrected
immediately.
(14) = Check front and rear suspension. Look for
damaged, loose or missing parts or parts showing signs
of wear or lack of lubrication. Replace parts as needed.

7-18
(15) = Adjust tire pressures as indicated on the GVW
Rating label for optimum tire life. See ªTiresº in the
Index for further details. Check tires for excessive or
abnormal wear or damage. Also check for damaged
wheels. Replace wheels and/or tires as needed.
(16) = Check spring
-to-axle U-bolts and shackle
bolts for proper torque. See the service manual for
torque sequence and specifications. When parts are
replaced, the torque must be checked and adjusted
more often during the first 6,000 miles (10 000 km).
Check torque at 500 miles (800 km) and 2,000 miles
(3 000 km) after first use of parts.
(17) = Check complete exhaust system and cab areas
near the exhaust system for broken, damaged, missing or
out
-of-position parts. Also inspect for open seams,
holes, loose connections or other conditions which could
let exhaust fumes seep into the driver compartment.
Needed repairs should be made at once. To help
maintain system integrity, replace exhaust pipes
whenever a new muffler is put on.
(18) = Check all gasoline engine drive belts for cracks,
fraying and wear. Replace as needed.(20) = With the engine off and below normal operating
temperature, check to see that the thermostatically
controlled engine cooling fan can be rotated by hand on
viscous
-operated drives. Replace as needed.
(21) = Check shields and underhood insulation for
damage or looseness. Adjust or replace as needed.
(23) = Wheel bearing service:

Grease type
-- Clean, inspect and lubricate with the
proper wheel bearing grease at designated intervals
or when hubs are removed. See ªRecommended
Fluids and Lubricantsº in the Index.

Oil
-filled type -- Some wheel bearings are lubricated
by rear axle lubricant. When you have oil
-filled
hubs, use lubricant identical to that used in your rear
axle. Lubricant change intervals are the same for
front and rear axles. However, you must maintain oil
level at the OIL LEVEL mark between change
intervals. See ªRecommended Fluids and
Lubricantsº in the Index.
(24) = Check the air intake system installation to see that
gaskets are seated properly and all hose connections,
fasteners and other components are tight. Tighten
connections and fasteners or replace parts as required.

7-19
(26) = Evaporative Control System Service
(if equipped): Check all fuel and vapor lines and hoses
for proper connections and correct routing (or every
24 months, whichever occurs first). Replace parts
as needed.
(28) = Replace spark plugs. Inspect wires for damage.
Check the wire boot and boot heat shield fit at spark
plugs and coil. Replace parts as needed.
(30) = Check the fuel tank, fuel cap and fuel lines for
damage which could cause leakage. Inspect fuel cap for
correct sealing ability and any indications of damage.
Check fuel cap gasket for even filler neck imprint.
Replace parts as needed.
(31) = Check EGR system as described in the
service manual. See ªService and Owner Publicationsº
in the Index.(32) = Inspect Electronic Vacuum Regulator Valve
(EVRV) filter for excessive contamination or plugging.
If needed, clean filter with solution of soap and water,
let dry and install.
(35) = Drain, flush and refill cooling system. See
ªRecommended Fluids and Lubricantsº in the Index for
what to use. Inspect hoses. Clean radiator, condenser,
pressure cap and neck. Pressure test cooling system and
pressure cap. For Caterpillar

diesel engines, always
refer to the Caterpillar Diesel Engine Operation &
Maintenance Manual for coolant recommendations and
change intervals.
(37) = Rear axle service: Change the lubricant. See
ªRecommended Fluids and Lubricantsº in the Index.
(38) = Front axle service: Re
-pack upper kingpin
roller bearing.

7-21
Part B: Owner Checks and Services
Listed in this part are owner checks and services which
should be performed at the intervals specified to help
ensure the safety, dependability and emission control
performance of your vehicle.
For your safety and that of others, any of the
safety
-related components that may have been damaged
in an accident should be checked and any needed repairs
made before operating the vehicle.
At the minimum, these routine checks should be made
every 6 months or 6,000 miles (10 000 km), whichever
occurs first. Whenever repairs are needed, have them
completed before operating the vehicle.
At Each Fuel Fill
It is important for you or a service station attendant to
perform these underhood checks at each fuel fill.Engine Oil Level Check
Check the engine oil level and add the proper oil
if necessary. See ªEngine Oilº in the Index for
further details.
Engine Coolant Level Check
Check the engine coolant level and add DEX
-COOL

coolant mixture if necessary. See ªEngine Coolantº in
the Index for further details.
Windshield Washer Fluid Level Check
Check the windshield washer fluid level in the
windshield washer tank and add the proper fluid if
necessary. See ªWindshield Washer Fluidº in the Index
for further details.
Tire Inflation Check
Check tire inflation cold. Make sure tires are inflated to
the pressures specified on the GVW Rating label. See
ªLoading Your Vehicleº and ªTiresº in the Index for
further details.