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Automatic Transmission Fluid
When to Check
A good time to check your automatic transmission fluid
level is when the engine oil is checked. See your
Allison Automatic Transmission Operator’s Manual to
find out when to change your transmission fluid
and filters.
How to Check and What to Use
The Allison Automatic Transmission Operator’s Manual
that came with the vehicle shows how to check the
automatic transmission fluid and what fluid to use.
Automatic Transmission External Filter
Your automatic transmission filter requires periodic
replacement.
Consult the Allison Automatic Transmission Operator’s
Manual that came with the vehicle for proper change
intervals.
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 6-31.
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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 6-31.
3. Reinstall the filler plug. Be sure the plug is fully
seated.
Cooling System
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.
If the coolant inside the coolant surge tank is boiling, do
not do anything else until it cools down. The vehicle
should be parked on a level surface.
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4. With the coolant surge tank pressure cap off, start
the engine and let it run until you can feel the upper
radiator hose getting hot. Watch out for the
engine cooling fan.
By this time, the coolant level inside the coolant
surge tank may be lower. If the level is lower, add
more of the proper mixture to the coolant surge tank
until the level reaches slightly above the FULL
COLD mark.
5. Then replace the pressure cap. Be sure the
pressure cap is hand-tight and fully seated.
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.
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If you get the overheat warning with no sign of steam,
try this for a minute or so:
1. In heavy traffic, let the engine idle in N (Neutral)
while stopped. If it is safe to do so, pull off the
road, shift to P (Park) or N (Neutral) and let
the engine idle.
2. Turn on your heater to full hot at the highest fan
speed and open the windows as necessary.
3. If climbing a hill, downshift to raise engine and fan
speeds.
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 vehicle until it
cools down.
You may decide not to lift the hood but to get service
help right away.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.
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Brakes
Brake Fluid
If the 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 the brake fluid.
{CAUTION:
Do not add brake fluid before checking the level or
there could be too much brake fluid. Brake fluid
could spill on the hot engine and it can catch fire.
You could be burned and the vehicle could be
damaged. See “Checking Brake Fluid” in this
section.
Checking Brake Fluid
Apply the brake pedal several times with the ignition off.
The brake fluid reservoir is in the engine compartment on
the driver side of the vehicle. Clean one of the reservoir
caps and the area around the cap, and remove it.
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The fluid level should be
even with the bottom ring of
the filler opening. If it is low,
add enough fluid to fill the
reservoir to the proper
level.
What to Add
Use the proper fluid listed in the 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
helps keep dirt from entering the reservoir.
{CAUTION:
With the wrong kind of fluid in the brake hydraulic
system, the brakes might not work well. This could
cause a crash. Always use the proper brake fluid.
Notice:
•Using the wrong fluid can badly damage brake
hydraulic system parts. For example, just a
few drops of mineral-based oil, such as engine
oil, in the brake hydraulic system can damage
brake hydraulic system parts so badly that they
will have to be replaced. Do not let someone
put in the wrong kind of fluid, and do not
use DOT-5 silicone brake fluid.
•If brake fluid is spilled on the vehicle’s painted
surfaces, the paint finish can be damaged. Be
careful not to spill brake fluid on the vehicle.
If you do, wash it off immediately. SeeWashing
Your Vehicle on page 5-90.
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Replacing Brake System Parts
The braking system on a vehicle is complex. Its many
parts have to be of top quality and work well together if
the vehicle is to have really good braking. The vehicle
was designed and tested with top-quality brake parts.
When parts of the braking system are replaced — for
example, when the brake linings wear down and new
ones are installed — be sure to get new approved
replacement parts. If this is not done, the brakes might
not work properly. For example, if someone puts in brake
linings that are wrong for the vehicle, the balance
between the front and rear brakes can change — for the
worse. The braking performance expected can change in
many other ways if the wrong replacement brake parts
are installed.
Hydraulic Brake Pads
Brake pad lining life will vary depending on
vehicle application, working environment, equipment
maintenance, and style of driving. The brake pad lining
wear rate has to be monitored for individual driving
habits — original equipment linings have mechanical
wear indicators to help with this. When down to the last
10% of the brake lining, the brake lining wear indicator
rubs on the rotor, causing a scratching or chirping
sound. When this sound is heard, service to the brake
pads is needed. SeeScheduled Maintenance on
page 6-5.
Aftermarket brake linings might not meet the same
stringent requirements as the original equipment linings.
Using aftermarket brake linings can affect braking
performance, pedal feel, noise, and lining wear.
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Air Brake Systems
If the vehicle has air brakes, it is important to get rid of
moisture in the system. Moisture will damage the 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 integral 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 of
full pressure, check the air pressure gage. It should read
at least 100 psi (692 kPa).
Air Dryer
If the vehicle has air brakes, it has an air dryer mounted
on the passenger side frame rail. 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 dryer has a filter that needs changing at intervals.
SeeScheduled Maintenance on page 6-5for more about
servicing this filter.
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