
GENERAL SERVICING GUIDELINES AND PRECAUTIONS
As with any machine, care should be taken to avoid being injured when
performing maintenance, repairs or system checks. Improper or
incomplete service could result in the vehicle not working properly
which, in turn, may result in personal injury or damage to the vehicle or
equipment. It is the operator’s responsibility to see that the vehicle
receives proper care and maintenance. If you have any questions about
performing some service, have the service done by a qualified technician.
Servicing guidelines
When servicing your vehicle, always:
•turn off the ignition unless the particular procedure calls for the
engine to be running.
•set the parking brake or chock the wheels.
•use support stands, not a jack, whenever you must be under a raised
vehicle.
•do not smoke.
•wear safety glasses for eye protection.
•operate the engine in a well-ventilated area
•do not work on the brakes or the clutch unless the proper precautions
are taken to avoid inhaling friction material dust.
•do not wear loose-fitting clothing, hanging jewelry, watches or rings.
•avoid contact with hot metal parts. Allow the hot components to cool
before working with, or around them.
Quality service parts are available through your dealer. If dealer parts are
not used, the owner must make sure that the parts that are being used
are equivalent quality to dealer parts.
The use of inferior parts can adversely affect the quality and
reliability of your vehicle which, in turn, can result in property
damage, personal injury or death.
Note:To avoid damage to the vehicle’s electrical components, disconnect
the positive (+) and negative (-) battery cables prior to electric welding.
Attach the welder ground cable as close as possible to the part being
welded. If it is necessary to weld close to an electrical component, it is
recommended that the electronic component be temporarily removed.
Follow the periodic lubrication procedures and regular inspection
intervals as outlined. Have your dealer or service center inspect your
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interval to determine if adjustment is necessary. Brake chamber push
rods on original equipment chambers now incorporate a stroke indicator
to aid in adjustment checks; an orange paint marker near the base of the
push rod. If the push rod is clean and the brakes require adjustment, the
orange marker can be seen protruding from the chamber when the
brakes are applied.
Slack adjusters should also be checked to ensure proper operation of the
adjuster mechanism at the six-month interval. Push rod travel should be
kept at a minimum without the brakes dragging.
Inspect the brake lining every maintenance interval. When brake lining or
blocks are worn to within 1/16 inch (1.6 mm) of rivets, brake lining must
be replaced. This inspection or adjustment should only be performed by
a qualified technician and must be in accordance with instructions
provided by the service manual.
Do not back off or disconnect the front brakes so that they are less
effective, letting the rear brakes do all the stopping of the vehicle. Do
not overlook the brakes on the trailer, either. Brake condition on the
trailer is just as important as the tractor. Proper brake balance on trucks
and tractor-trailers is essential for effective braking.
Once a year, the entire brake system must be inspected. Check the
following:
•Any rubber as it may deteriorate whenever used. Rubber brake
components should be inspected by a qualified technician and
replaced as necessary. Replacement intervals vary according to the
severity and length of vehicle service.
•Condition of brake drums, brake chambers and slack adjusters.
•System for air leaks.
•Hose or pipes for rust, damage and deterioration.
•Operation of service and parking brakes.
Some parts such as air brake chamber diaphragm, air compressor and air
cleaner should be inspected periodically and replaced if considered
unserviceable.
Air brakes - air dryer
Performance of desiccant or after-cooler type air dryers is dependent on
climatic conditions in which your vehicle is operating. Maintenance
schedules must be established for each specific operation.
The use of an air dryer on a vehicle does not eliminate the need to
periodically drain the air reservoirs.
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Hydraulic brakes - fluid precautions
The Hydro-Max brake system consists of two completely separate
hydraulic systems operating with two different and incompatible fluids;
power steering fluid and hydraulic brake fluid. Failure to observe
precautions preventing the contamination of either system with fluid
from the other will result in swelling and deterioration of rubber parts
leading to reduced brake performance and eventual brake failure.
To avoid fluid contamination, the following should always be observed:
1. Use only fluids specified (or equivalent) and properly identified.
2. Add fluids only to the following locations:
•Power steering fluid to the power steering fluid pump reservoir
•Brake fluid to the brake master cylinder
Hydraulic brakes - brake lines, hoses and fittings
Inspect these components every 4,000 miles (6,000 km).
•Check lines for kinks, dents, corrosion or rupture.
•Check hoses for abrasions, kinks, soft spots or rupture, collapse,
cracks, twists or loose frame supports. When replacing a hose, be sure
there is adequate clearance to the hose to avoid an abrasion to the
new hose.
•Examine all connections for leaks.
•Repair or replace brake line tubes, hoses or fittings as required.
Driveline parking brake
Parking brake adjustment should only be performed by a qualified
technician, and in accordance with the instructions in the service
manual.
Use wheel chocks and exercise caution when inspecting under
the vehicle. A vehicle roll-away could result in property damage,
personal injury or death.
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OPENING THE HOOD
The hood and fenders are held in position by a latch located on each
fender.
The parking brake must be fully set before opening the hood or
possible personal injury may occur.
If you must leave the engine running while checking under the
hood, do not allow any loose clothing, jewelry, hair or other
items to get near moving engine components or possible personal
injury may occur.
To open the hood:
1. Set the parking brake, shift into N (Neutral) (automatic transmission)
or 1 (First) (manual transmission) and turn the engine off.
2. Lift upward on the bottom of
each latch.
3. Pull the bottom of each latch
away from the fender.
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3. Set the parking brake and shift into N (Neutral) (automatic
transmission) or 1 (First) (manual transmission).
4. Turn off the engine and wait a few minutes for the oil to drain
completely into the oil pan.
5. Open the hood.
6. Locate and carefully remove the
engine oil level indicator (dipstick).
7. Wipe the indicator clean. Insert the indicator fully, then remove it
again.
•If the oil level isbetween ADD and OPERATING RANGE,the oil
level is acceptable.DO NOT ADD OIL.
•Maintain the oil level between ADD and OPERATING RANGE on the
dipstick by adding oil as required.
•The distance from ADD to OPERATING RANGE on the dipstick
represents 2.0 quarts (1.9L).
•Oil levels above OPERATING RANGE may cause engine damage. Some
oil must be removed from the engine by a qualified service technician.
8. Put the indicator back into the engine and ensure it is fully seated.
Engine oil and filter recommendations - Cummins B and Caterpillar
engines
Refer to the appropriate engine operator’s manual for information on the
engine oil.
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POWER STEERING FLUID
Check the power steering fluid level using the following procedure. Refer
to the general maintenance information section for the recommended
service intervals. If adding fluid is necessary, use only MERCONAT F.
1. Set the parking brake, shift into N (Neutral) (automatic transmission)
or 1 (First) (manual transmission) and turn the engine off.
2. Open the hood.
3. Clean the top of the power steering fluid reservoir.
4. Remove the dipstick from the reservoir and wipe the dipstick clean.
5. Reinstall the dipstick. Remove it again and check the fluid level.
•If the fluid temperature is at
approximately 68°F - 120°F (20°C
-49°C) (fluid cool or warm to
the touch), check the COLD side
of the dipstick. The fluid level
should be within the FULL range
•If the fluid level is below the ADD
line, add fluid in small amounts,
continuously checking the level until it reaches the proper level.
•If the fluid temperature is at
approximately 176°F–230°F
(80°C - 110°C) (fluid too hot to
touch), check the HOT side of
the dipstick. The fluid level
should be within the FULL range.
•If the fluid level is below the ADD
line, add fluid in small amounts,
continuously checking the level until it reaches the proper level.
Note:The fluid level may also be checked by looking at the see-through
plastic reservoir. Make sure that the fluid is within the minimum and
maximum fluid range as marked on the reservoir.
A low fluid level may indicate a leak in the power steering system.
Inspect the power steering system and repair the leak. If necessary, see
your dealer or a qualified service technician.
To avoid damage to the power steering system,do notoperate the
vehicle with a low power steering fluid level.
Whenever the dipstick is installed, make sure it is properly seated and
tightened securely.
ADD MAX. COLDFULL
ADD MAX. HOTFULL
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CLUTCH FLUID/LINKAGE ADJUSTMENTS
Clutch fluid (if equipped)
Check the clutch fluid level. Refer to the general maintenance
information section for the service interval schedules.
During normal operation, the fluid level in the clutch reservoir should
remain constant. If the fluid level drops, maintain the fluid level at the
step in the reservoir.
Use only a DOT 3 brake fluid designed to meet manufacturer
specifications. Refer toLubricant specificationsin this chapter.
1. Set the parking brake, shift into 1
(First) and turn the engine off.
2. Open the hood.
3. Clean the reservoir cap before
removal to prevent dirt and water
from entering the reservoir.
4. Remove cap and rubber
diaphragm from reservoir.
5. Add fluid until the level reaches
the step in the reservoir.
6. Reinstall rubber diaphragm and cap onto reservoir.
Clutch linkage (if equipped)
Lubricate the clutch linkage using the following procedure. Refer to the
general maintenance information section for the service interval
schedules.
Use a grease which meets manufacturer specifications. Refer to
Lubricant specificationsin this chapter.
1. Set the parking brake, shift into 1 (First) and turn the engine off.
2. Remove the inspection cover from the clutch housing.
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•Transmission and clutch
removed for clarity.
3. With a grease gun, lubricate the clutch release bearing (at one
location) and the clutch release shaft (at two locations) using the grease
fittings provided.
4. Lubricate clutch release wear pads at the two locations where they
contact the clutch release bearing using a brush or similar tool.
5. Install the inspection cover onto the clutch housing.
TRANSMISSION FLUID
Always dispose of used automotive fluids in a responsible manner.
Follow your community’s standards for disposing of these types of fluids.
Call your recycling center to find out about recycling automotive fluids.
Automatic transmission fluid
Refer to your Allison Automatic Transmission Operator’s Manual for
scheduled intervals for transmission fluid checks and changes. Your
transmission does not consume fluid. However, the fluid level should be
checked if the transmission is not working properly, i.e., if the
transmission slips or shifts slowly or if you notice some sign of fluid
leakage.
Automatic transmission fluid expands when warmed. To obtain an
accurate fluid check, drive the vehicle until it is warmed up
(approximately 20 miles [30 km]). If your vehicle has been operated for
an extended period at high speeds, in city traffic or during hot weather,
the vehicle should be turned off for about 30 minutes to allow fluid to
cool before checking.
1. Drive the vehicle 20 miles (30 km) or until it reaches normal operating
temperature.
2. Park the vehicle on a level surface and engage the parking brake.
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