Priming the 7.8L Isuzu 6H Diesel Engine
If your vehicle is equipped with the 7.8L Isuzu 6H
diesel engine, use the following procedure to
prime the engine:
1. Make sure there is fuel in the fuel tank.
2. Make sure the specified fuel filter is properly
installed.
3. Make sure the fuel lines are securely
connected.
4. Make sure the fuel filter is cool to the touch.
5. Use a clean cloth to remove dirt and oil
from the fuel filter head and breather valve.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, 4.9
Y(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.
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Wheel Loading
Wheels are stamped with a maximum load and
cold inflation rating. Be sure you do not exceed
these limits. If you ever think you need to exceed
these limits, first contact the rim and wheel
maker to get their advice.
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 325for
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 321andIn ation - Tire
Pressure on page 322for more information on
proper tire inflation.
323
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 363for further information.
Wheel Replacement
Replace any wheel that is bent, cracked or badly
rusted or corroded. If wheel nuts keep coming
loose, replace the wheel. If the wheel leaks
air, replace it.
Your dealer will know the kind of wheel you need.
Each new wheel should have the same
load-carrying capacity, diameter, width, offset and
be mounted the same way as the one it replaces.If you need to replace any of your wheels, wheel
bolts or wheel nuts, replace them only with
new GM original equipment parts. This way, you
will be sure to have the right wheel, wheel
bolts and wheel nuts for your vehicle.
{CAUTION:
A leaking wheel could fail without warning.
A wheel designed for tubeless tires could
be leaking because it is damaged. Do not
use an inner tube or some other thing to try
to stop the leaking. Get a new wheel of the
proper type.
328
Your truck, when new, did not include tire changing
equipment or a place to store a tire in the
vehicle. Few drivers of these vehicles have the
necessary equipment aboard to be able to change
a flat tire safely. 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 are stopped somewhere by a flat or
damaged tire or wheel, you should get expert help.
SeeRoadside Assistance Program on page 408.
Appearance Care
Cleaning the Inside of Your Vehicle
Your vehicle’s interior will continue to look its
best if it is cleaned often. Although not always
visible, dust and dirt can accumulate on your
upholstery. Dirt can damage carpet, fabric, leather,
and plastic surfaces. Regular vacuuming is
recommended to remove particles from your
upholstery. It is important to keep your upholstery
from becoming and remaining heavily soiled.
Soils should be removed as quickly as possible.
Your vehicle’s interior may experience extremes of
heat that could cause stains to set rapidly.
Lighter colored interiors may require more frequent
cleaning. Use care because newspapers and
garments that transfer color to your home
furnishings may also transfer color to your
vehicle’s interior.
331
(13)= 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.
(14)= Adjust tire pressures as indicated on the
Certification or Tire Information label for optimum
tire life. SeeTires on page 321for 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.
387
•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, service brake chambers, quick
release valves, quick release/double check
valve combinations, parking brake control
valve, double check valves, pressure
protection valves, and ether 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 325.
(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.
390