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Manual Transmission Fluid
When to Check
A good time to have it checked is when the engine oil is
checked. Refer to the Maintenance Schedule to find out
when to check and change your manual transmission
fluid. SeeScheduled Maintenance on page 6-5.
How to Check and What to Use
Check the fluid level only when your engine is off, the
vehicle is parked on a level place, and the transmission
is cool enough for you to rest your fingers on the
transmission case.
To check the transmission fluid level, do the following:
1. Remove the filler plug.
2. Check to be sure that the lubricant level is up to the
bottom of the fill opening. On heavy duty
transmissions, an inch of oil level equals about
one gallon of fluid.
3. If the fluid level is good, reinstall the plug and be
sure it is fully seated. If the fluid level is low, add
more fluid as described in the next steps. Refer to
the Maintenance Schedule to determine what
kind of fluid to use. SeePart C: Recommended
Fluids and Lubricants on page 6-32.
How to Add Fluid
To add transmission fluid, do the following:
1. Remove the filler plug.
2. Add fluid at the filler plug hole. Add only enough
fluid to bring the fluid level up to the bottom of the
fill opening. Refer to the Maintenance Schedule
to determine the proper fluid to use. SeePart C:
Recommended Fluids and Lubricants on page 6-32.
3. Reinstall the filler plug. Be sure the plug is
fully seated.
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Adding Coolant
If you need more coolant, add the proper DEX-COOL®
coolant mixtureat the surge tank, but only when the
engine is cool.
{CAUTION:
You can be burned if you spill coolant on hot
engine parts. Coolant contains ethylene glycol,
and it will burn if the engine parts are hot
enough. Do not spill coolant on a hot engine.
When replacing the pressure cap, make sure it is
hand-tight.
Engine Coolant
(Caterpillar
®Diesel Engines)
If your vehicle has a Caterpillar®diesel engine, see the
Caterpillar®Diesel Engine Operation & Maintenance
Manual provided with your vehicle to find out what
to add, as well as when and how to service your
cooling system.
Coolant Surge Tank Pressure Cap
The coolant surge tank pressure cap is located in
the engine compartment, on the driver’s side of
the vehicle.
Notice:Your vehicle’s surge tank pressure cap is
designed for use with medium-duty cooling systems
only. If the surge tank pressure cap is not tightly
installed, coolant loss and possible engine damage
may occur. Be sure the cap is properly and tightly
secured.
Engine Overheating
You will find an engine coolant temperature gage, as
well as a low coolant warning light, on your vehicle’s
instrument panel. SeeEngine Coolant Temperature
Gage on page 3-35andLow Coolant Warning Light on
page 3-35for more information.
Your vehicle also has a check gages warning light on
the instrument panel. SeeCheck Gages Warning
Light on page 3-42for more information.
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If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning does not come back on, you can drive
normally.
If the warning continues and you have not stopped,
pull over, stop, and park your vehicle right away.
If there is still no sign of steam, you can push down the
accelerator until the engine speed is about twice as
fast as normal idle speed for at least three minutes while
you are parked. If you still have the warning,turn off
the engine and get everyone out of the vehicleuntil it
cools down.
You may decide not to lift the hood but to get service
help right away.Cooling System
(Gas and DURAMAX
®Engines)
When you decide it is safe to lift the hood, here is what
you will see:
A. Engine Fan
B. Coolant Surge Tank
If your vehicle has a Caterpillar
®diesel engine, see the
Caterpillar®Diesel Engine Operation and Maintenance
Manual provided with your vehicle.
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Engine Fan Noise
Your vehicle has a clutched engine cooling fan. When
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions, the clutch is not fully engaged. This improves
fuel economy and reduces fan noise. Under heavy
vehicle loading, trailer towing and/or high outside
temperatures, the fan speed increases when the clutch
engages. So you may hear an increase in fan noise.
This is normal and should not be mistaken as the
transmission slipping or making extra shifts. It is merely
the cooling system functioning properly. The fan will
slow down when additional cooling is not required and
the clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch disengages.
Power Steering Fluid
SeeScheduled Maintenance on page 6-5to determine
when to check your power steering fluid.
How To Check Power Steering Fluid
Check your power steering fluid only when the engine is
warm. If the engine is not warm, you probably will not
get an accurate reading.
If the fluid level is between the MIN (Minimum) and
MAX (Maximum) marks, you have enough. If you need
fluid, add only enough of the proper fluid to bring it
in between the MIN and MAX marks.
If your power steering fluid level is low, this can cause
the brake or service brakes soon warning lights to come
on. In addition, the steering effort and emergency
brake distance could increase.
If either light remains on after you have added power
steering fluid to the proper level, then shut off the engine
for 10 seconds. This should reset the brake warning
lights. If one or both lights stay on, see “Hydraulic Brake
System Warning Lights” underBrake System Warning
Light on page 3-31for more information.
What to Use
To determine what kind of fluid to use, seePart C:
Recommended Fluids and Lubricants on page 6-32.
Notice:When adding power steering uid or
making a complete uid change, always use the
proper uid. Failure to use the proper uid can
cause leaks and damage hoses and seals.
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Brakes
Brake Fluid
If your vehicle has
hydraulic brakes, there is a
brake master cylinder in
the engine compartment
on the driver side of
the vehicle. Refer to the
Maintenance Schedule to
determine when to
check your brake fluid.
{CAUTION:
Do not add brake uid before you check the
level. If you do, you could get too much brake
uid. Brake uid could spill on the hot engine
and it can catch re. You could be burned and
your vehicle could be damaged. See “Checking
Brake Fluid” in this section.
Checking Brake Fluid
Apply the brake pedal several times with the ignition off.
Then clean one of the reservoir caps and the area
around the cap, and remove it.
The fluid level should be
even with the bottom ring
of the filler opening.
The brake fluid reservoir is
located in the engine
compartment on the driver
side of the vehicle.
If it is low, add enough fluid to fill the reservoir to the
proper level.
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What to Add
Use the proper fluid listed in your Maintenance
Schedule. Use new brake fluid from a sealed
container only.
Always clean the brake fluid reservoir cap/cover and the
area around the cap/cover before removing it. This
will help keep dirt from entering the reservoir.
{CAUTION:
With the wrong kind of uid in your brake
system, your brakes may not work well, or they
may not even work at all. This could cause a
crash. Always use the proper brake uid.Notice:
Using the wrong uid can badly damage brake
system parts. For example, just a few drops of
mineral-based oil, such as engine oil, in your
brake system can damage brake system
parts so badly that they will have to be replaced.
Do not let someone put in the wrong kind of
uid, and do not use DOT-5 silicone brake uid.
If you spill brake uid on your vehicle’s painted
surfaces, the paint nish can be damaged. Be
careful not to spill brake uid on your vehicle. If
you do, wash it off immediately. SeeAppearance
Care on page 5-79.
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Air Brake Systems
If your vehicle has air brakes, it is important to get rid of
moisture in your system. Moisture will damage your
system if it is not removed daily.
There are two ways to do this. One is automatic through
the air brake vehicle’s air dryer with intregal automatic
moisture ejector that purges air from the system through
a self-contained reservoir. The other way to drain
moisture from the air brake system is to manually
activate drain valves at each reservoir. Drain the air
reservoirs occasionally to be sure the air dryer is
working properly.
Drain the air brakes at full system pressure. To be sure
you are at full pressure, check your air pressure
gage. It should read at least 100 psi (692 kPa).
Air Dryer
If your vehicle has air brakes, it will have an air dryer.
This collects and removes dirt, moisture, or other foreign
matter from the air prior to entering the brake system.
The dryer also acts as a moisture ejector. It
automatically ejects the moisture when the compressor
cycles. The purge tank has a manual drain valve
that must be drained every day. See “Air Brake
Systems” for the manual drain procedure. The air dryer
is mounted on the passenger side frame rail.
The dryer has a filter that you need to change at
intervals. SeeScheduled Maintenance on page 6-5for
more about servicing this filter.
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Electric Air Compressor
Your vehicle may have an electric air compressor. This
compressor is used to run options that require
pressurized air, such as air horn, air seat, 7.8L engine
exhaust restrictor, or 7.8L engine exhaust brake.
The air compressor is used when vehicles are not
equipped with an air brake system.
The air supply for this
system must be
maintained by releasing
the drain valve to eject any
moisture that may have
built up in the system.
It is recommended that this system be drained on a
weekly basis.
Clutch Pedal Free Travel
If you have a V8 engine and a manual transmission,
your clutch will need adjustment when pedal free travel
gets down to about 1/4 inch (32 mm), as measured
at the clutch pedal pad. You should have 1 1/2 to
2 inches (38 to 51 mm) of clutch pedal free travel.
If your clutch ever needs service, be sure to use only
GM clutch replacement parts.
Chassis Lubrication
Your Maintenance Schedule provides all of the required
chassis lubrication intervals and identifies proper
lubricants to use. Be sure to see your Maintenance
Schedule before performing any chassis lubrication
service. To determine location of chassis lubrication
items, use the following charts.
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