WARNING(Continued)
•Do not change from aluminum wheels to steel wheels or vice-versa
without changing the mounting hardware where required or, in some
cases with flange nut mounting systems, changing the hub and stud
assembly. Mixing components could cause wheel or fastener failures
and result in property damage, personal injury, or death.
WARNING:An inflated tire and rim can be very dangerous if
improperly used, serviced or maintained. To avoid serious injury,
never attempt to re-inflate a tire which has been run flat or seriously
under-inflated without first removing the tire from the wheel assembly
for inspection. Do not attempt to add air to tires or replace tires or
wheels without first taking precautions to protect persons and property.
All tires with Steel Carcass Plies (if equipped):This type of tire
utilizes steel cords in the sidewalls. As such, they cannot be treated like
normal light truck tires. Tire service, including adjusting the air pressure,
must be performed by personnel trained, supervised and equipped
according to Federal Occupational Safety and Health Administration
(OSHA) regulations. For example, during any procedure involving tire
inflation, the technician or individual must utilize a remote inflation
device, and make sure that all persons are clear of the trajectory area.
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Stay out of the trajectory (1) as indicated in the illustration.
WARNING:Do not mount tube type tires on tubeless wheels or
tubeless tires on tube type wheels. To do so could result in tire
or wheel failure and cause property damage, personal injury or death.
Preserving proper inflation pressure is a very important maintenance
practice to make sure safe vehicle operation and long life for the tires.
Failure to maintain correct inflation pressure may result in sudden tire
destruction, improper vehicle handling, and may cause rapid and
irregular tire wear. Therefore, inflation pressures should be checked daily
and always before long distance trips.
Follow the tire manufacturer’s recommended cold inflation pressure for
the tire size, type, load range (ply rating) and axle loading typical for
your operation. (Each steer axle tire load equals one-half steer axle
loading; each drive tire load is one-quarter the axle-loading if fitted with
four tires).
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Checking Tire Pressure
Always check inflation pressure when tires are cold. Never bleed air from
hot tires to relieve normal pressure build-up. Normal increase in pressure
due to service conditions is 10–15 psi (69–103 kPa), which is allowable
in truck tires.
Tires should be properly inflated to manufacturers’ recommended
pressure for the size and service load in which the vehicle is being used.
See the specific tire manufacturer with which your vehicle is equipped
with for the latest information concerning service load and inflation
pressure.
It is particularly important to keep moisture from the inside of tires, and
proper selection of air compressor equipment, proper air line routing,
and the use of shop air dryers is strongly recommended to avoid
moisture in the high pressure air used for tire inflation.
Under-inflation
Do not allow tires to become under-inflated; increased flexing due to
under-inflation causes heat build-up within the tire components. This
leads to reduced strength, breakdown of the rubber compounds, and
possible separation of the tire components (such as ply and tread
separation and reduced retreadability).
Under-inflation is the primary cause of premature tire concerns including
sudden loss of air. In addition, low inflation causes an increase in rolling
resistance. This results in reduced fuel mileage, a loss in tread mileage,
and uneven wear due to increased tread movement. To determine proper
inflation, see the tire manufacturer load and inflation guide, which you
can find on the tire manufacturer website or at your local truck tire
dealer.
Tire Inspection
Check the tires for abnormal wear patterns and proper inflation
pressures. Repair or replace cut or broken tire casings.
Inspect tires for the following conditions. If any are present, remove and
repair, retread, or scrap the tire as the condition dictates.
•Any blister, bump or raised portion anywhere on the surface of the
tire tread or sidewall (other than a bump made by a repair). These
indicate the start of internal separation.
•Any cut that reaches to the belt or ply cords, or any cut that is large
enough to grow in size and depth.
•Any nail or puncturing object.
•If a tread groove is holding a stone or object that is starting to drill
into the tread base, remove the object.
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Irregular Wear:If irregular wear is present, check the axle alignment,
tire pressure, wheel balancing, shock and suspension component
condition, and wheel bearing end play.
This condition not only shortens tire life, but also adversely affects the
handling of your vehicle, which is dangerous.
Rotating tires from one wheel position to another is an often-used way to
even out many types of irregular wear or to avoid it altogether. Some of
the more effective tire rotation programs are:
•You can rotate steer tires that have developed some type of irregular
wear pattern to drive axles if using rib tires on all wheel positions.
Applying steer tires to a drive position often cleans them. You can
move them back to the steer axles or run out to re-tread stage on the
rear axle.
•Another rotation possibility for fleets with rib tires in all wheel
positions is to break in the new steer tires in the drive axle positions,
then move them to steer axles. This wears away tread rubber
relatively quickly in the early life of a tire when it is most likely to
develop an unusual wear pattern.
•You can place drive axle tires on the other end of the same axle to
reverse the direction of rotation. This is often helpful if a heel and
toe or alternate lug wear pattern has developed.
You can help minimize irregular wear by:
•Using the right inflation pressure for the load being carried.
•Maintaining proper front wheel alignment, especially toe-in, to
specifications.
•Maintaining proper tire and wheel balance.
•Maintaining shock absorbers and suspension components.
Use of Tire Chains
See the chain manufacturer’s recommendation for correct tire chain
usage, installation and removal.
WHEELS
General Information
Note:Remember to replace the wheel air valves when replacing the road
tires at the end of their useful lives.
Inspect, lubricate and adjust wheel bearings at regular intervals. This is
especially important if operating in deep sand, mud or water. See the
Capacities and Specificationschapter.
Mount wheel balance weights on the dome-side of the wheel only. Failure
to do so may result in loss of wheel weight or damage to brakes or
wheels.
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Oil-lubricated Front Wheel Bearings
During normal vehicle duty cycle, the lubricant and air inside the
hub/wheel cavity expands and, if not vented, causes pressure build-up
that could cause accelerated seal wear. You can use two venting methods
to prevent pressure build-up:
•A slit or small hole in the rubber check vent
•The window.
Over a period, if not routinely cleaned, a slight film of oil can collect dirt
around the rubber fill plug and face, which could appear to be a leak.
Routine cleaning helps make sure that you can easily observe the
lubricant level through the window as intended. In situations where the
window is clean on the outside but discolored on the inside, you can
check the lubricant level by inserting a finger through the rubber check
vent hole.
The specified lubricant level for a window-type hubcap is from the
minimum line to five–sixteenth inch (8 millimeters) above the minimum
line. If the lubricant level should suddenly drop dramatically below the
minimum level, see theWorkshop Manualfor diagnostic procedure.
Installation, Tightening and Alignment
Make sure the threads on the studs and nuts are clean to permit correct
torque when installing wheels. The mounting surfaces of rims, wheels,
spacer rings and clamps must be free of dirt, rust, lubricants or damage.
Use a wire brush to clean the mounting contact surfaces. Do not use
lubricant on threads.
After properly tightening the rim or wheel, check it for proper alignment.
Rotate the wheel with a piece of chalk attached to a steady, firm surface,
and placed to just barely clear the outside surface of the tire bead seat;
this procedure points out the high spot. A high spot does not necessarily
indicate unevenly tightened lug nuts, but may be the result of a bent
wheel.
Use the following installation procedure:
1. Slide inner rear or front tire and wheel in position over studs and push
it back as far as possible. Use care so you do not damage the threads on
the studs.
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Observation Maintenance Operation
Insufficient power shown in loaded
practice stop.Inspect the automatic slack
adjuster function.
Subpar vehicle handling qualities. Check the operation of the brakes,
clutch and steering.
1,2
Excessive noise from under the
cab or engine compartment.Inspect your vehicle for missing,
damaged or mislocated noise
shields.
Excessive engine noise. Check the engine performance and
the engine governor.
Engine overheats; excessive fan
noise; fan constantly runs at high
speed or wobbles due to worn
bearings.Inspect the fan, fan shroud and fan
clutch.
Excessive exhaust noise; you smell
exhaust fumes.Inspect the entire exhaust system
for holes, leaks, breakage,
looseness and corrosive damage.
Excessive engine compartment
noise.Inspect the engine air induction
system (including air ducts and air
filter) for loose, damaged or
missing components.
Poor steering; wandering;
excessive tire wear.Check front end alignment, inspect
the tires and tire pressure.
3
Vibration or abnormal tire wear
indicating imbalance.Balance the wheels and the tires.
Hard shifting or excessive
vibration.Check the transmission and engine
mountings.
2
High effort to shift; noisy
transmission.Check and adjust transmission
controls.2
Insufficient full-throttle power;
backfiring.Check fuel pump pressure.
Radiator cap does not hold
pressure.Clean the cap seal and cap surface
on the radiator.
Electrical power supply has
diminished.Check the battery terminals for
corrosion.
344Scheduled Maintenance
2015 F-650/750(f67)
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Canadian_French(fr_can)