1999 GMC C-SERIES Owners Manual

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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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7-23
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 Certification/Tire label.
See ªTiresº in the Index for further details.
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7-24 At Least Twice a Year
Restraint System Check
Make sure the safety belt reminder light (if equipped)
and all your belts, buckles, latch plates, retractors and
anchorages are working properly. Look for any other
loose or damaged safety belt system parts. If you see
anything that might keep a safety belt system from
doing its job, have it repaired. Have any torn or frayed
safety belts replaced.
Wiper Blade Check
Inspect wiper blades for wear or cracking. Replace blade
inserts that appear worn or damaged or that streak or
miss areas of the windshield. Also see ªWiper Blades,
Cleaningº in the Index.
Weatherstrip Lubrication
Silicone grease on weatherstrips will make them last
longer, seal better, and not stick or squeak. Apply
silicone grease with a clean cloth. During very cold,
damp weather more frequent application may be
required. (See ªRecommended Fluids and Lubricantsº
in the Index.)Body Lubrication Service
Lubricate all surfaces such as door checks, door lock
bolts, lock strike plates, door hinge bushings and
dovetail bumper wedges. Where oil holes are provided,
a dripless oil can be used. The seat adjusters, seat track,
door weatherstrips and rubber hood bumpers should also
be lubricated.
Part C tells you what to use. More frequent lubrication may
be required when exposed to a corrosive environment.
Parking Brake Check
Park on a fairly steep hill and hold the vehicle with the
parking brake only. This checks holding ability.
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7-25
Starter Switch Check
CAUTION:
When you are doing this check, the vehicle could
move suddenly. If it does, you or others could be
injured. Follow the steps below.
1. Before you start, be sure you have enough room
around the vehicle.
2. Firmly apply both the parking brake (see ªParking
Brakeº in the Index if necessary) and the
regular brakes.
NOTE: Do not use the accelerator pedal, and be
ready to turn off the engine immediately if it starts.
3. On automatic transmission vehicles, try to start the
engine in each gear. The starter should work only in
PARK (P), if equipped, or NEUTRAL (N). If the
starter works in any other position, your vehicle
needs service.Automatic Transmission Shift Indicator Check
Check that the indicator points to the gear chosen.
Steering Check
Be alert for any changes in steering action, abnormal
front tire wear or steering wheel position. An inspection
or service is needed when the steering wheel is harder to
turn or has too much free play, or if there are strange
sounds when turning or parking.
Brake System Check
Be alert to illumination of the low air warning lamp or
for the tone alarm, or changes in braking action, such as
repeated pulling to one side, unusual sounds when
braking or increased brake pedal travel. Make sure air
brake system reservoirs are drained daily with full
system air pressure, and check system for leaks. Any of
these conditions could indicate the need for brake
system inspection and/or service.
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7-26
Engine Cooling System Service
Inspect the hoses and have them replaced if they are
cracked, swollen or deteriorated. Inspect all pipes,
fittings and clamps; replace as needed. Clean the outside
of the radiator and air conditioning condenser. To help
ensure proper operation, a pressure test of the cooling
system and pressure cap is recommended at least once
a year.
Exhaust System Check
Be alert for any changes in the sound of the exhaust
system or any smell of fumes. These are signs the
system may be leaking. Have it checked and/or repaired
at once. Refer to ªEngine Exhaustº and ªRunning Your
Engine While You're Parkedº in the Index.
Windshield Wipers and Washers Check
Check operation and condition of the wiper blades.
Check the flow of the washer spray.
Defroster Check
Move the control to the defrost symbol and the fan to HI
or the high symbol. Then check the airflow from the
ducts at the inside base of the windshield.Mirrors and Sun Visors Check
Check that friction joints hold mirrors and sun visors
in place.
Seat Adjuster Check
When adjusting a manual seat, be sure seat adjusters
latch by attempting to move the seat after latching.
Lamps Check
Check panel lighting, warning lights, indicator lights
and interior lamps. On the outside, check: license plate
lamps, sidemarker lamps, reflectors or lights on outside
mirrors, headlamps, parking lamps, identification and
clearance lamps, taillamps, brake lamps, turn signals,
backup lamps and hazard warning flashers. Have
headlamp aim checked at once if beams seem
improperly aimed.
Glass, Mirrors, Lamps and/or Reflectors
Condition Check
Look for broken, scratched, dirty or damaged glass,
mirrors, lamps or reflectors that could reduce the view
or visibility or cause injury. Replace, clean or
repair promptly.
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7-27
Door Latches Check
Check that doors close, latch and lock tightly. Check for
broken, damaged or missing parts that might prevent
tight latching.
Hood Latches Check
Check that the hood closes firmly. Check for broken,
damaged, loose or missing parts that might prevent tight
latching. Make sure the secondary latch (if equipped)
keeps the hood from opening all the way when the
primary latch is released.
Fluid Leaks Check
Check for fuel, coolant, oil or other fluid leaks by
looking at the surface beneath the vehicle after it has
been parked for a while.
Underbody Inspection
Corrosive materials used for ice, snow removal and dust
control can collect on the underbody. If these materials
are not removed, accelerated corrosion (rust) can occur
on underbody parts such as fuel lines, frame, floor pan
and exhaust system. At least every spring, flush these materials from the underbody with plain water. Take
care to clean well any areas where mud and other debris
can collect. Sediment packed in closed areas of the
frame should be loosened before being flushed.
Engine Cover Check
Check that the cab's engine cover and seal (if equipped)
are not torn or damaged. Be sure that the cover is bolted
down firmly to the floor.
At Least Once a Year
Key Lock Cylinders Service
Lubricate the key lock cylinders with the lubricant
specified in Part C.
Underbody Flushing Service
At least every spring, use plain water to flush any
corrosive materials from the underbody. Take care to
clean thoroughly any areas where mud and other debris
can collect.
Tractor Protection (Breakaway) Valve Check
On air brake models, remove, disassemble, clean and
inspect the tractor protection (breakaway) valve.
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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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