service CHEVROLET C/K 2003 Repair Manual

7-9
Wheel bearing (grease type) service (or every
24 months, whichever occurs first, and whenever
hubs are removed). (23)(46)
Inspect door hinge pins and bushings and replace
as necessary.
Steering system service. (13)
Front and rear suspension service. (14)
Spring
-to-axle U-bolts and shackle
bolts service. (16)
Exhaust system service (or every 6 months,
whichever occurs first). (3)(4)(17)
Wheels and tires service. (15)
Hydraulic brake service (or every 6 months,
whichever occurs first). (7)(46)
Parking brake service (or every 6 months, whichever
occurs first). (8)
Thermostatically controlled engine cooling fan
service. (4)(20)
Shields and underhood insulation service. (4)(5)(21)
Rear axle air shift motor service. (11)
Air intake system service (or every 24 months,
whichever occurs first). (4)(5)(24)
Evaporative Control System service (if equipped) (or
every 24 months, whichever occurs first). (3)(26)
Air brake service (or every 6 months, whichever
occurs first). (39)
Air brake automatic slack adjuster service
(or every 500 hours, whichever occurs first). (40)
Check air brake relay valve operation and check for
leaks (or every month, or every 300 hours,
whichever occurs first).
Clean air brake application valve (or every 3 months,
or every 300 hours, whichever occurs first); lubricate
linkage.
Air brake chamber service (or every 2 months,
whichever occurs first). (41)
Trailer brake hand control valve service (or every
3 months, or every 900 hours, whichever
occurs first). (42)
L18/LB7 Engines Only: Clutch pedal free
travel service. (10)
50,000 Miles (80 000 km)
DURAMAX Diesel Only: Change engine oil
and filter (or every 12 months, whichever occurs
first). (2)(3)
Inspect air compressor discharge port (or every
6 months or every 1,800 hours, whichever
occurs first).

7-10
52,500 Miles (84 000 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)
60,000 Miles (96 000 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)

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

Gasoline Engine Only (Vehicles with GVW greater
than 16,000 lbs.): Spark plug service. (3)(28)

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

DURAMAX Diesel Only: Replace fuel filter.

Chassis lubrication service (or every 6 months,
whichever occurs first). (12)
Replace fuel filter(s) (or every 12 months, whichever
occurs first). (3)

Inspect door hinge pins and bushings and replace
as necessary.

Steering system service. (13)

Front and rear suspension service. (14)

Spring
-to-axle U-bolts and shackle bolts
service. (16)

Exhaust system service (or every 6 months,
whichever occurs first). (3)(4)(17)

Wheels and tires service. (15)

Hydraulic brake service (or every 6 months,
whichever occurs first). (7)(46)

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

C600, C700 and C800 Gasoline Engines Only:
Engine drive belts service (or every 12 months,
whichever occurs first). (18)

Thermostatically controlled engine cooling
fan service. (4)(20)

Shields and underhood insulation service. (4)(5)(21)

Air compressor dry element pleated paper air strainer
service (or every 2 months or every 800 hours,
whichever occurs first).

L18/LB7 Engines Only: Clutch pedal free
travel service. (10)

7-11
67,500 Miles (108 000 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)
Cooling system service. Clean the cooling system
filler cap with clean water, clean the core, pressure
test the cap and the system for proper pressure
capability and inspect condition of cooling and
heater hoses and clamps. Replace hoses if cracked,
swollen or damaged.
Wheel bearing (grease type) service (or every
24 months, whichever occurs first, and whenever
hubs are removed). (23)(46)
Wheels and tires service. (15)
Parking brake service (or every 6 months, whichever
occurs first). (8)
Rear axle air shift motor service. (11)
Air intake system service (or every 24 months,
whichever occurs first). (4)(5)(24)Evaporative Control System service (if equipped) (or
every 24 months, whichever occurs first). (3)(26)

Air brake service (or every 6 months, whichever
occurs first). (39)
Air brake automatic slack adjuster service (or every
500 hours, whichever occurs first). (40)
Check air brake relay valve operation and check
for leaks (or every month, or every 300 hours,
whichever occurs first).
Clean air brake application valve (or every 3 months,
or every 300 hours, whichever occurs first); lubricate
linkage.
Air brake chamber service (or every 2 months,
whichever occurs first). (41)
Trailer brake hand control valve service
(or every 3 months, or every 900 hours,
whichever occurs first). (42)
L18/LB7 Engines Only: Clutch pedal free
travel service. (10)
70,000 Miles (112 000 km)
DURAMAX Diesel Only: Change engine
oil and filter (or every 12 months, whichever
occurs first). (2)(3)

7-12
75,000 Miles (120 000 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)
Chassis lubrication service (or every 6 months,
whichever occurs first). (12)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(6)
DURAMAX Diesel Only: Replace fuel filter.
Steering system service. (13)
Front and rear suspension service. (14)
Spring
-to-axle U-bolts and shackle bolts
service. (16)
Exhaust system service (or every 6 months,
whichever occurs first). (3)(4)(17)
Wheels and tires service. (15)
Fuel tank, fuel cap and fuel lines service (or every
72 months, whichever occurs first). (3)(30)

EGR system inspection (or every 72 months,
whichever occurs first). (3)(31)
Hydraulic brake service (or every 6 months,
whichever occurs first). (7)(46)
Parking brake service (or every 6 months,
whichever occurs first). (8)
Thermostatically controlled engine cooling
fan service. (4)(20) Shields and underhood insulation service. (4)(5)(21)
L18/LB7 Engines Only: Clutch pedal free
travel service. (10)
80,000 Miles (128 000 km)
DURAMAX Diesel Only: Change engine
oil and filter (or every 12 months, whichever
occurs first). (2)(3)
Air compressor dry element pleated paper air strainer
service (or every 2 months or every 800 hours,
whichever occurs first).
82,500 Miles (132 000 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)
Wheel bearings service
-- Eaton Axle (oil-filled) (or
every 24 months, whichever occurs first). (23)(46)
Parking brake service (or every 6 months, whichever
occurs first). (8)
L18/LB7 Engines Only: Clutch pedal free
travel service. (10)

7-13
90,000 Miles (144 000 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)

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

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

DURAMAX Diesel Only: Replace fuel filter.

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

Cooling system service. Clean the cooling system
filler cap with clean water, clean the core, pressure
test the cap and the system for proper pressure
capability and inspect condition of cooling and
heater hoses and clamps. Replace hoses if cracked,
swollen or damaged.

Wheel bearing (grease type) service (or every
24 months, whichever occurs first, and whenever
hubs are removed). (23)(46)

Replace fuel filter(s) (or every 12 months, whichever
occurs first). (3)
Steering system service. (13)

Front and rear suspension service. (14)

Spring
-to-axle U-bolts and shackle
bolts service. (16)

Exhaust system service (or every 6 months,
whichever occurs first). (3)(4)(17)

Inspect door hinge pins and bushings and replace
as necessary.

Wheels and tires service. (15)

Hydraulic brake service (or every 6 months,
whichever occurs first). (7)(46)

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

C600, C700 and C800 Gasoline Engines Only:
Engine drive belts service (or every 12 months,
whichever occurs first). (18)

Thermostatically controlled engine cooling fan
service. (4)(20)

Shields and underhood insulation service. (4)(5)(21)

Rear axle air shift motor service. (11)

Air intake system service (or every 24 months,
whichever occurs first). (4)(5)(24)
(Continued)

7-14
90,000 Miles (144 000 km) (Continued)
Evaporative Control System service (if equipped) (or
every 24 months, whichever occurs first). (3)(26)

Air brake service (or every 6 months, whichever
occurs first). (39)
Air brake automatic slack adjuster service (or every
500 hours, whichever occurs first). (40)
Check air brake relay valve operation and check
for leaks (or every month, or every 300 hours,
whichever occurs first).
Clean air brake application valve (or every 3 months,
or every 300 hours, whichever occurs first); lubricate
linkage.
Air brake chamber service (or every 2 months,
whichever occurs first). (41)
Trailer brake hand control valve service (or every
3 months, or every 900 hours, whichever
occurs first). (42)
L18/LB7 Engines Only: Clutch pedal free
travel service. (10)
97,500 Miles (156 000 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)
100,000 Miles (160 000 km)
DURAMAX Diesel Only: Change engine
oil and filter (or every 12 months, whichever
occurs first). (2)(3)
Diesel Only: Inspect engine drive belt; replace
as necessary.
Gasoline Engine Only (Vehicles with GVW of
16,000 lbs. or less): Spark plug service. (3)(28)
Change power steering fluid (or every 36 months,
whichever occurs first). (13)
Replace power steering reservoir filter element
(or every 24 months, whichever occurs first).
Front axle service. (38)
Rear axle service
-- Eaton, Rockwell, Spicer Axles
(or every 12 months, whichever occurs first). (37)

7-15

Exhaust brake service (if equipped). Check for
excessive spindle free play and smooth operation.
Lubricate ball joint cap.

Air compressor dry element pleated paper air strainer
service (or every 2 months or every 800 hours,
whichever occurs first).

Inspect air compressor discharge port (or every
6 months or every 1,800 hours, whichever
occurs first).

Manual transmission (ZF 6
-speed only) fluid
replacement (or every 48 months, whichever
occurs first).
120,000 Miles (192 000 km)

C600, C700 and C800 Gasoline Engines Only:
Replace engine drive belts.
150,000 Miles (240 000 km)

Cooling system service (or every 60 months since
last service, whichever occurs first). (3)(35)

Diesel Engine Only: Inspect engine drive belt;
replace as necessary.
200,000 Miles (320 000 km)

Remove, disassemble, clean and inspect the air
brake trailer supply valve (or every 2 years, or
every 7,200 hours, whichever occurs first).

Diesel Engine Only: Inspect engine drive belt;
replace as necessary.

C400 and C500 Gasoline Engines Only: Inspect
drive belts; replace as necessary. (18)
250,000 Miles (400 000 km)

Wheel bearings service -- Eaton Axle (oil-filled) (or
every 36 months, whichever occurs first). (23)(46)

Rear axle service
-- Eaton, Rockwell, Spicer Axles
(or every 36 months, whichever occurs first). (37)

Manual transmission (except ZF 6
-speed) fluid
replacement (or every 60 months, whichever
occurs first).
300,000 Miles (480 000 km)

Remove, disassemble, clean and inspect the air brake
air dryer (or every 3 years, or 10,800 hours,
whichever occurs first). Replace dessicant on
Bendix
-Westinghouse units.

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.