6. Use the palm of your hand to repeatedly press and
release the plunger (1) at the top of the fuel filter
priming pump. Continue until the plunger resistance
becomes firm. This may take from 20 to 100 times,
depending upon fuel tank location.
7. Turn the fuel filter breather valve screw (2)
counterclockwise several turns to open the
breather valve.
8. Use the palm of your hand to repeatedly press and
release the plunger (1) at the top of the fuel filter
priming pump until fuel begins to seep from
the breather valve.
9. Tighten the fuel filter breather screw (2) to the
specified torque, 4.9Y(43 in. lbs).
10. Use the palm of your hand to press and release the
plunger (1) at the top of the fuel filter priming pump
about 20 more times. This sends fuel to the engine.
11. Use a clean cloth to remove any fuel from the fuel
filter and surrounding area.
12. Start the engine and allow it to idle for a few minutes.
13. Check the fuel filter for leakage.Running Out of Fuel
If the diesel engine stalls and you think that you have
run out of fuel, do this to restart your engine:
{CAUTION:
Diesel fuel is ammable. It could start a re if
it gets on hot engine parts. You could be
burned. Do not let too much fuel ow from the
air bleed valve, and wipe up any spilled fuel
with a cloth.
1. If you are parked on a level surface, add at least
2 gallons (7.6 liters) of fuel. However, if you are
parked on a slope, you may need to add up
to 5 gallons (18.9 liters) of fuel.
2. Follow the fuel priming procedure earlier in this
section to prime the fuel filter.
3. Close the air bleed valve.
4. Turn the ignition key to START for 10 to 15 seconds
at a time until your engine starts. If the engine tries
to run, but does not run smoothly, increase the
rpm a little using the accelerator pedal. This will help
force air through the system.
5-15
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.
SeeTightening the Wheel Nuts on page 5-73for wheel
nut tightening information and proper torque values.
{CAUTION:
If you operate your vehicle with a tire that is
badly underin ated, the tire can overheat. An
overheated tire can lose air suddenly or catch
re. You or others could be injured. Be sure all
tires (including the spare, if any) are properly
in ated.
SeeTires on page 5-70andIn ation - Tire Pressure on
page 5-71for more information on proper tire inflation.
When It Is Time for New Tires
Replace your tires when the tread depth is down to
1/8 of an inch (3.2 mm) for the front tires, or 1/16 of an
inch (1.6 mm) for a rear tire. Also, you need a new
tire if:
•You can see cord or fabric showing through the
tire’s rubber.
•The tread or sidewall is cracked, cut or snagged
deep enough to show cord or fabric.
•The tire has a bump, bulge or split.
•The tire has a puncture, cut or other damage that
can’t be repaired well because of the size or
location of the damage.
{CAUTION:
Mixing tires could cause you to lose control
while driving. If you mix tires of different
types — like radial and bias-belted tires — the
vehicle may not handle properly, and you
could have a crash. Be sure to use the same
type of tires all around.
5-72
{CAUTION:
If wheel studs are damaged, they can break. If
all the studs on a wheel broke, the wheel could
come off and cause a crash. If any stud is
damaged because of a loose-running wheel, it
could be that all of the studs are damaged. To
be sure, replace all studs on the wheel. If the
stud holes in a wheel have become larger, the
wheel could collapse in operation. Replace any
wheel if its stud holes have become larger or
distorted in any way. Inspect hubs and
hub-piloted wheels for damage. Because of
loose running wheels, piloting pad damage may
occur and require replacement of the entire hub,
for proper centering of the wheels. When
replacing studs, hubs, wheel nuts or wheels, be
sure to use GM original equipment parts.
{CAUTION:
Rust or dirt on a wheel, or on the parts to
which it is fastened, can make 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 places
where the wheel attaches to the vehicle. In an
emergency, you can use a cloth or a 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. SeeScheduled Maintenance on page 6-5
for further information.
5-76
For example, you would need a truck jack that can lift
several thousand pounds and a torque wrench that can
generate several hundred foot-pounds (Y)of
twisting force.
{CAUTION:
If you try to put air back into a tire that has run
at, even a tire that was extremely low on air,
the tire can have a sudden air-out. This could
cause you to lose control of the vehicle and
have a serious crash. Do not re ll a at or very
low tire with air without rst having the tire
taken off the wheel and checked for damage.
So if you’re stopped somewhere by a flat or damaged
tire or wheel, you should get expert help. SeeRoadside
Assistance Program on page 7-5.
Appearance Care
Cleaning products can be hazardous. Some are toxic.
Other cleaning products can burst into flames if a match
is struck near them or if they get on a hot part of the
vehicle. Some are dangerous if their fumes are inhaled
in an enclosed space. When anything from a container
is used to clean the vehicle, be sure to follow the
manufacturer’s warnings and instructions. Always open
the doors or windows of the vehicle when cleaning
the inside.
Never use these to clean the vehicle:
•Benzene
•Naphtha
•Carbon Tetrachloride
•Acetone
•Paint Thinner
•Turpentine
•Lacquer Thinner
•Nail Polish Remover
5-79
(14)= Adjust tire pressures as indicated on the Gross
Vehicle Weight (GVW) Rating label for optimum tire life.
SeeTires on page 5-70for further details. Check
tires for excessive or abnormal wear or damage. Also
check for damaged wheels. Replace wheels and/or tires
as needed.
(15)= 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.
(16)= 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.
(17)= Check all gasoline engine drive belts for cracks,
fraying, and wear. Replace as needed.
(18)= Adjust valve lash. Incorrect valve clearance
will result in increased engine noise and reduced engine
output.(19)= 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.
(20)= Check shields and underhood insulation for
damage or looseness. Adjust or replace as needed.
(21)= Inspect parking brake drum and linings for wear
or cracks and check linkage and adjustment.
(22)= Wheel bearing service:
•Grease type — Clean, inspect, and lubricate with
the proper wheel bearing grease at designated
intervals or when hubs are removed. SeePart C:
Recommended Fluids and Lubricants on page 6-32.
•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 the proper oil level between change
intervals. SeeFront Wheel Bearings with Oil-Filled
Hubs on page 5-69andPart C: Recommended
Fluids and Lubricants on page 6-32.
(23)= 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.
6-24
•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 engine air cleaner filter
replacement.
•Remove, disassemble, clean, and inspect the safety
valve, standard brake chambers, quick release
valves, quick release/double check valve
combinations, parking brake control valve, double
check valves, pressure protection valves, and
alcohol injector (if equipped).
•Remove, disassemble, and clean the application
valve; replace parts showing wear.
•Remove, disassemble, clean, and inspect the
spring brake control valve; replace rubber parts.(33)= Clean and lubricate air brake automatic slack
adjuster. Check pushrod travel and auto adjustment
operation. Have serviced if needed.
(34)= Air brake chamber service: Check operation,
mounting clamps, and air lines and check for leaks.
(35)= Trailer brake hand control valve service: Check
operation; lubricate cam and follower.
(36)= Tighten the wheel stud nuts to the specified
torque values at 100 miles (160 km). Thereafter, tighten
them 1,000 miles (1 600 km) after each time the
wheel is removed. SeeTightening the Wheel Nuts on
page 5-73.
(37)= Inspect and clean any accumulated dirt, gravel,
or other foreign objects from the valves and valve boots
as needed. Using light oil, lubricate brake pedal to
brake application valve linkage components. Check any
rubber boots for cracks, holes, or deterioration and
replace if necessary.
6-26