1999 GMC C-SERIES torque

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If a Tire Goes Flat
It's unusual for a tire to ªblow outº while you're driving,
especially if you maintain your tires properly. If air goes
out of a tire, it's much more likely to leak out slowly.
But if you should ever have a ªblowout,º here are a few
tips about what to expect and what to do:
If a front tire fails, the flat tire will create a drag that
pulls the vehicle toward that side. Take your foot off the
accelerator pedal and grip the steering wheel firmly.
Steer to maintain lane position, and then gently brake to
a stop well out of the traffic lane.
A rear blowout, particularly on a curve, acts much like a
skid and may require the same correction you'd use in a
skid. In any rear blowout, remove your foot from the
accelerator pedal. Get the vehicle under control by
steering the way you want the vehicle to go. It may be
very bumpy and noisy, but you can still steer. Gently
brake to a stop
-- well off the road if possible.
If a tire goes flat, the next part tells you what to do.
Changing a Flat Tire
A flat or damaged tire can be a major roadside problem.
You're very likely to have to go for help. Few drivers of
these vehicles have the necessary equipment aboard to
be able to change a flat tire safely. For example, youhave to have a truck jack that can lift several thousand
pounds and a torque wrench that can generate several
hundred foot
-pounds (newton-meters) of twisting force.
So if you're stopped somewhere by a flat or damaged
tire or wheel, you should get expert help right then.
If the correct equipment is available, though, here is the
procedure to follow.

Does the tire still seem to have air under pressure in
it? If so, stand to the side and look at the wheel. See
if it looks like another wheel on the vehicle. If so, go
on to the next step. If it doesn't, or even if you can't
be sure, stop and get expert help.
CAUTION:
Tire-rim assemblies can explode. If you work on
a pressurized tire mounted on a damaged wheel,
the assembly can expand with explosive force
without warning. You and others nearby can be
badly injured. Don't work around a tire that has
air under pressure in it when its wheel is or might
be damaged.
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CAUTION:
Incorrect wheel nuts or improperly tightened
wheel nuts can cause the wheel to become loose
and even come off. This could lead to an accident.
Be sure to use the correct wheel nuts. If you have
to replace them, be sure to get new GM original
equipment wheel nuts.
Stop somewhere as soon as you can and have the
nuts tightened with a torque wrench.
See ªTightening the Wheel Nutsº in the Index for
the proper torque for your particular wheel.
NOTICE:
Improperly tightened wheel nuts can lead to
brake pulsation and rotor damage. To avoid
expensive brake repairs, evenly tighten the wheel
nuts in the proper sequence and to the proper
torque specification.
If You're Stuck: In Sand, Mud,
Ice or Snow
In order to free your vehicle when it is stuck, you will
need to spin the wheels, but you don't want to spin your
wheels too fast. The method known as ªrockingº can
help you get out when you're stuck, but you must
use caution.
CAUTION:
If you let your tires spin at high speed, they can
explode, and you or others could be injured. And,
the transmission or other parts of the vehicle can
overheat. That could cause an engine
compartment fire or other damage. When you're
stuck, spin the wheels as little as possible. Don't
spin the wheels above 35 mph (55 km/h) as shown
on the speedometer.
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6-50 Rims and Wheels
Rims and wheels are stamped with a maximum load and
cold inflation rating. Be sure you don't exceed these limits.
Dual Tire Operation
When the vehicle is new, or whenever a wheel, wheel
bolt or wheel nut is replaced, check the wheel nut torque
as indicated:
If your vehicle has stud piloted or hub piloted wheels,
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.
For proper torque, see ªWheel Nut Torqueº in the Index.
The outer tire on a dual wheel setup generally wears
faster than the inner tire. Your tires will wear more
evenly and last longer if you rotate the tires periodically.
If you're going to be doing a lot of driving on
high
-crown roads, you can reduce tire wear by adding
5 psi (35 kPa) to the tire pressure in the outer tires. Be
sure to return to the recommended pressures when no
longer driving under those conditions. See ªChanging a
Flat Tireº in the Index for more information.
CAUTION:
If you operate your vehicle with a tire that is
badly underinflated, the tire can overheat. An
overheated tire can lose air suddenly or catch
fire. You or others could be injured. Be sure
all tires (including the spare, if any) are
properly inflated.
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Then, follow the steps below for the wheels you have.
Cast
-Type Wheel
1. Put the tire and rim assembly on the axle hub.
2. Install the rim spacer at the rear.
3. Install the outer rear tire and rim assembly so that its
valve stem is exactly opposite the valve stem on the
inner tire and rim assembly.
4. Install the rim clamps and nuts. Position
them properly.
NOTICE:
If you tighten a nut when a rim clamp is not
positioned properly, it can damage the rim and
also cause the wheel to wobble in operation. Be
sure to position the rim clamps properly before
you go on to the next step.
5. Finger-tighten the nuts. Be sure that all of the wheel
clamps are seated all the way around the wheel.
6. Tighten all of the nuts using the following diagram.
Be sure to use the one that matches your wheels.
7. Now repeat Step 6, but this time tighten the nuts to
200 lb
-ft (271 N´m) of torque.
8. Turn the wheel and measure along the sidewall to see
how much wheel run
-out there is. There should be
no more than 1/8 inch (3 mm) on the front wheels
and 3/16 inch (5 mm) on the rear wheels. If there is
too much wheel run
-out, you can try loosening the
nuts on the side where there is the most run
-out and
tightening the opposite nuts. When you finally have
the tire running true, tighten all of the nuts to
200 lb
-ft (271 N´m).
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Stud-Piloted 10-Stud Wheel
The studs and nuts used on the right side of the vehicle
have right
-hand threads. Those used on the left side
have left
-hand threads. It is easy to tell by looking at the
nuts, because they are stamped R or L.
1. Put the tire and rim assembly on the axle hub.
2. Put on the wheel nuts. If you use oil or grease on the
wheel studs or nuts, the wheel nuts can't tighten
properly. This could let the wheel come off as you
are driving.
3. Finger
-tighten the nuts on the rear inner wheels and
the front wheels.
4. Tighten these nuts to 575 lb
-ft (780 N´m), unless
you have aluminum wheels and/or aluminum hubs.
If you have aluminum wheels and/or aluminum
hubs, tighten the nuts only to 475 lb
-ft (644 N´m).
Use the following diagram to do this.
Front or Inner Dual
WheelOuter Dual Wheel
5. Install the outer rear tire and rim assembly so that its
valve stem is exactly opposite the valve stem on the
inner tire and rim assembly.
6. Put on the wheel nuts.
7. Finger
-tighten the wheel nuts.
8. Tighten the nuts to the same torque numbers shown
in Step 4.
Whenever tightening both the inner and outer rear wheel
nuts, first loosen the outer wheel nuts. Then tighten the
inner nuts. Finally, tighten the outer nuts.
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CAUTION:
Rust or dirt on a wheel, or on the parts to which
it is fastened, can make the wheel nuts become
loose after a time. The wheel could come off and
cause an accident. When you change a wheel,
remove any rust or dirt from the places where the
wheel attaches to the vehicle. In an emergency,
you can use a cloth or 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 every 1,000 miles (1 600 km).
When your vehicle is new or when a wheel or fastener is
new you should have a technician tighten the wheel
stud and rim clamp nuts, with a torque wrench, at
100, 500 and 1,000 miles (160, 800 and 1 600 km).
The reason for this is that the clamping system has to
seat before the fasteners will stay tightened.
Wheel Replacement
Replace any wheel that is bent, cracked or badly rusted.
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.
CAUTION:
A leaking wheel could fail without warning. A
wheel designed for tubeless tires could be leaking
because it is damaged. Don't use an inner tube or
some other thing to try to stop the leaking. Get a
new wheel of the proper type.
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Replacement Bulbs
It is recommended that you use an AC
type bulb
whenever you need to replace one.
Before you replace any bulbs, be sure that all lamps are
off and the engine isn't running.
Capacities and Specifications
Replacement part numbers listed in this section are
based on the latest information available at the time of
printing. They are subject to later change. If a part listed
here isn't the same as the part in your vehicle when it
was built, or if you have any questions, please contact
your GM Truck dealer.
Engine Identification and Data
Engine RPO LG5 LP4/L21
Engine Type 7.2L L6 7.4L V8
Fuel System HEUI SPFI
Firing Order
1
-5-3-6-2-41-8-4-3-6-5-7-2
Wheel Nut Torque
Refer to ªTightening the Wheel Nutsº in this section for
wheel nut torque information.
Cooling System Capacity
Model Quarts (Liters)
7.2L 32.0 (30.0). . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
with automatic transmission 30.0 (28.4). . . . . . . . . .
7.4L 25.0 (23.7). . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
with automatic transmission 23.0 (22.7). . . . . . . . . .
Above capacities (volumes) are approximate.
Crankcase Capacity
Capacities (volumes) shown are for normal refill. Add
oil as indicated when the oil filter element is changed.
Capacities given are approximate
-- keep level within
the operating range. Do not operate with fluid level
below the ADD line.
Engine
Capacity
-- Quarts (Liters)
7.2L 21 (19.0)*
7.4L 8 (7.5)
*Additional oil is required with auxiliary oil filter
systems. Make sure to add enough extra oil to fill the
auxiliary oil filter system. For vehicles equipped with
the LUBERFINER 750
-C, add 14 quarts (13.25 L).
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Air Conditioning Refrigerants
Not all air conditioning refrigerants are the same.
If the air conditioning system in your vehicle needs
refrigerant, be sure the proper refrigerant is used.
If you're not sure, ask your dealer.
Air Conditioning Refrigerant Capacity
Refrigerant R-134a 2.5 lbs. (1.134 kg). . . . . . . . . . . .
This capacity (volume) is approximate.
Normal Maintenance Replacement
Parts
Allison Transmission External Filters
Engine GM (AC) Part Number
7.2L 25011122 (PF897). . . . . . . . . . . . . . . . . . . . . . .
7.4L 25011122 (PF897). . . . . . . . . . . . . . . . . . . . . . .
Air Compressor Filter
Air Compressor GM Part Number
Bendix Tu
-Flo
550 (13.2 CFM)2467368
Service Replacement Part and
Filter Recommendations
Engine 7.2L 7.4L
RPO LG5 LP4/L21
Spark Plug Ð AC Type R41
-932
ÐGap Ð 0.060 inch
(1.52 mm)
ÐTorque Ð 22.0 lb. ft.
(30.0 Nm)
Oil Filter CAT

2P4004 AC Type PF-932
PCV Valve Ð AC Type CV
-774C
Air Cleaner* Donaldson
P522606Donaldson
P533355
Fuel Filter AC
-TP-915 Pri-
mary**AC Type GF-481
Pressure Caps RC
-54 Ð
*Optional Davco (K28) D350921 spin
-on type filter
located in component box.
**Optional Cold Weather (KUK) Racor B6484GM
spin
-on type located in component box. Optional Davco
heated fuel water separator mounted on the side of the
diesel engine.
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