1999 GMC C-SERIES maintenance

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7-2
Have you purchased the GM Protection Plan? The Plan
supplements your new vehicle warranties. See your
Warranty and Owner Assistance booklet, or your
GM dealer for details.
Introduction
Your Vehicle and the Environment
Proper vehicle maintenance not only helps to keep your
vehicle in good working condition, but also helps the
environment. All recommended maintenance procedures
are important. Improper vehicle maintenance can even
affect the quality of the air we breathe. Improper fluid
levels or the wrong tire inflation can increase the level
of emissions from your vehicle. To help protect our
environment, and to keep your vehicle in good
condition, please maintain your vehicle properly.
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7-3 How This Section is Organized
This maintenance schedule is divided into five parts:
ªPart A: Scheduled Maintenance Servicesº shows
what to have done and how often. Some of these
services can be complex, so unless you are technically
qualified and have the necessary equipment, you should
let your dealer's service department or another qualified
service center do these jobs.
CAUTION:
Performing maintenance work on a vehicle can
be dangerous. In trying to do some jobs, you can
be seriously injured. Do your own maintenance
work only if you have the required know
-how
and the proper tools and equipment for the job.
If you have any doubt, have a qualified
technician do the work.
If you are skilled enough to do some work on your
vehicle, you will probably want to get the service
information. See ªService and Owner Publicationsº in
the Index.ªPart B: Owner Checks and Servicesº tells you
what should be checked and when. It also explains what
you can easily do to help keep your vehicle in
good condition.
ªPart C: Recommended Fluids and Lubricantsº
lists some recommended products to help keep your
vehicle properly maintained. These products, or their
equivalents, should be used whether you do the work
yourself or have it done.
ªPart D: Maintenance Recordº provides a place
for you to record the maintenance performed on your
vehicle. Whenever any maintenance is performed, be
sure to write it down in this part. This will help you
determine when your next maintenance should be done.
In addition, it is a good idea to keep your maintenance
receipts. They may be needed to qualify your vehicle for
warranty repairs.
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7-4
Part A: Scheduled Maintenance
Services
Using Your Maintenance Schedule
We at General Motors want to help you keep your
vehicle in good working condition. But we don't know
exactly how you'll drive it. You may drive very short
distances only a few times a week. Or you may drive
long distances all the time in very hot, dusty weather.
You may use your vehicle in making deliveries or in
many other ways.
Because of all the different ways people use their
vehicles, maintenance needs vary. You may need more
frequent checks and replacements. So please read the
following and note how you drive. If you have any
questions on how to keep your vehicle in good
condition, see your GM dealer.
This part tells you the maintenance services you should
have done and when you should schedule them. If you
go to your dealer for your service needs, you'll know
that GM
-trained and supported service people will
perform the work using genuine GM parts.The proper fluids and lubricants to use are listed in Part C.
Make sure whoever services your vehicle uses these. All
parts should be replaced and all necessary repairs done
before you or anyone else drives the vehicle.
This schedule is for vehicles that:

carry passengers and cargo within recommended
limits. You will find these limits on your vehicle's
Certification/Tire label. See ªLoading Your Vehicleº
in the Index.

are driven on reasonable road surfaces within legal
driving limits.

use the recommended fuel. See ªFuelº in the Index.
Scheduled Maintenance Supplements
If your vehicle has a Caterpillar diesel engine, your
GM Owner's Manual is supplemented by the Caterpillar
Diesel Engine Operation & Maintenance Manual. If your
vehicle has an Allison transmission, your GM Owner's
Manual is supplemented by an Allison Transmission
Operator's Manual. Always refer to these manuals for
related maintenance services.
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7-5
Scheduled Maintenance
The services shown in this schedule up to 100,000 miles
(166 000 km) should be performed after 100,000 miles
(166 000 km) at the same intervals. The services shown
after 100,000 miles (166 000 km) should be performed
at those same intervals.
This vehicle has 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 Oil Life Indicator will indicate
that a change is necessary.
See ªFootnotesº at the end of this Maintenance Schedule
for further explanation of maintenance services and
Caterpillar

diesel application.
100 Miles (160 km)
Wheel stud nut service. (45)
500 Miles (800 km)
Wheel stud nut service. (45)
1,000 Miles (1 600 km)
Wheel stud nut service. (45)(46)
3,000 Miles (5 000 km)
Engine oil and filter service. (3)(9)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
Clutch pedal free travel service. (10)
Rear axle air shift motor service. (11)
6,000 Miles (10 000 km)
Engine oil and filter service. (3)(9)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
Chassis lubrication service (or every 6 months,
whichever occurs first). (12)
Lubricate door hinge pins and rollers with engine oil.
Wheels and tires service. (15)
Hydraulic brake service (or every 6 months,
whichever occurs first). (7)
Hydraulic parking brake service (or every 6 months,
whichever occurs first). (8)
Clutch pedal free travel service. (10)
9,000 Miles (15 000 km)
Engine oil and filter service. (3)(9)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
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7-18 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) = Check the fluid level in the manual transmission.
(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, clutch
master cylinder (if equipped), 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. 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 hydraulic parking brake drum and linings
for wear or cracks and check linkage and adjustment.
Check spring brake actuator and pump for leaks.
Note: The spring brake section of the actuator is
non
-serviceable.
(9) = This vehicle has an Engine Oil Life Monitor. This
monitor will show you when to change the engine oil
and filter
-- usually between 3,000 miles (5 000 km) and
7,500 miles (12 500 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 (12 500 km) or 12 months
without an oil and filter change.
The system won't detect dust in the oil. So if you drive
in a dusty area, be sure to change your oil and filter
every 3,000 miles (5 000 km) or sooner if the Change
Oil Light comes on. Remember to reset the Oil Life
Monitor whenever the oil is changed. For more
information, see ªChange Oil Lightº in the Index.
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7-21
(25) = Check thermostatically controlled air cleaner
installation to make certain that all ducts are connected and
correctly installed. Also, check valve for proper operation.
(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.
(27) = Replace air cleaner filter (or every 24 months,
whichever occurs first). Replace filter more often if
driving in dusty conditions. Ask your dealer for the
proper replacement intervals for your driving conditions.
(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.(33) = Check the PCV system for proper operation and
clean PCV valve. Replace hoses as needed.
(34) = Replace PCV valve and blow out the PCV valve
hose with compressed air. Replace hoses as needed.
(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.
(39) = Air brake service:

Inspect brake lines and hoses for proper hook
-up,
binding, leaks, cracks, chafing, etc. Inspect drum
brake linings for wear or cracks. Inspect other brake
parts at each wheel, including drums, wheel cylinders
and piston heat shields and boots. 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.
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7-22

Test air lines for leaks; tighten as needed. Replace
compressor filter.

Inspect air parking brake chamber for leaks and
damage. Inspect lines and hoses for leaks, cracks,
chafing, etc. Also check all attachments for
tightness, wear or damage. Note: The spring brake
section of the rear brake diaphragms are
non
-serviceable.

Replace the air compressor filter element, mounted
on the air compressor. For remote air compressor
intake service, refer to air cleaner filter replacement.
(40) = Clean and lubricate air brake automatic slack
adjuster. Check pushrod travel and auto adjustment
operation. Have serviced if needed.
(41) = Air brake chamber service: Check operation,
mounting, clamps and air lines and check for leaks.
(42) = Trailer brake hand control valve service: Check
operation; lubricate cam and follower.
(44) = Air brake service: Remove, disassemble, clean
and inspect the safety valve, standard brake chamber,
quick release valve, quick release/double check valve
combination, parking brake control valve, double check
valve, pressure protection valve and alcohol injector. Remove, disassemble and clean the application valve;
replace parts showing wear. Remove, disassemble, clean
and inspect the spring brake control valve; replace
rubber parts.
(45) = For Stud Piloted Wheels Only: Tighten the wheel
stud nuts to the specified torque values at 100 miles
(160 km), 500 miles (800 km) and 1,000 miles
(1 600 km) and then every 1,000 miles (1 600 km)
thereafter. See ªTightening the Wheel Nutsº in
the Index.
(46) = For Hub Piloted Wheels Only: Tighten the wheel
stud nuts to the specified torque values at 1,000 miles
(1 600 km). Thereafter, tighten them 1,000 miles
(1 600 km) after each time the wheel is removed. See
ªTightening the Wheel Nutsº in the Index.
(47) = Short Trip/City Maintenance Schedule. See
ªMaintenance Schedule Definitionº in the introduction
pages at the beginning of this section.
(48) = Long Trip/Highway Maintenance Schedule. See
ªMaintenance Schedule Definitionº in the introduction
pages at the beginning of this section.
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7-28
Part C: Recommended Fluids
and Lubricants
NOTE: Fluids and lubricants identified below by
name, part number or specification may be obtained
from your dealer.
USAGE
FLUID/LUBRICANT
Engine Oil
(Gasoline
Engine)Engine Oil with the American
Petroleum Institute Certified For
Gasoline Engines ªStarburstº
symbol of the proper viscosity. To
determine the preferred viscosity
for your vehicle's engine, see
ªEngine Oilº in the Index.
Engine Oil
(Caterpillar
Diesel Engine)See the Caterpillar
Operation &
Maintenance Manual for Engine
Oil recommendations.
Engine Coolant
(GM Gasoline
Engine)50/50 mixture of clean, drinkable
water and use only GM
Goodwrench

DEX-COOL
or
Havoline
DEX-COOL

Coolant. See ªEngine Coolantº in
the Index.
USAGEFLUID/LUBRICANT
Engine Coolant
(Caterpillar
Diesel Engine)See the Caterpillar
Operation &
Maintenance Manual for Engine
Coolant recommendations.
Hydraulic Brake
SystemDelco Supreme 11
Brake Fluid
(GM Part No. 12377967 or
equivalent DOT
-3 Brake Fluid).
Windshield
Washer SolventGM Optikleen
Washer Solvent
(GM Part No. 1051515)
or equivalent.
Clutch Bearing
LubricantClutch Bearing Lubricant (GM
Part No. 12345777 or equivalent)
or NLGI #3 consistency.
Exhaust Brake
Ball Joint Cap
LubricantHigh-Temperature Grease (GM
Part No. 1051344 or equivalent) or
NLGI #3 consistency.
Spring Parking
Brake Hydraulic
PumpDEXRON
-III Automatic
Transmission Fluid.
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