
ESSENTIAL TOWING CHECKS
See Load limits in the Load Carrying
chapter for load specification terms found
on the tire label and Safety Compliance
label and instructions on calculating your
vehicle's load.
Remember to account for the trailer
tongue weight as part of your vehicle load
when calculating the total vehicle weight.
Hitches
Do not use a hitch that either clamps onto
the bumper or attaches to the axle. You
must distribute the load in your trailer so
that 10-15% of the total weight of the
trailer is on the tongue.
Safety Chains
Note: Do not attach safety chains to the
bumper.
Always connect the safety chains to the
frame or hook retainers of your vehicle
hitch.
To connect the safety chains, cross the
chains under the trailer tongue and allow
enough slack for turning tight corners. Do
not allow the chains to drag on the ground.
Trailer Brakes WARNING
Do not connect a trailer's hydraulic
brake system directly to your
vehicle's brake system. Your vehicle
may not have enough braking power and
your chances of having a collision greatly
increase. Electric brakes and manual, automatic or
surge-type trailer brakes are safe if you
install them properly and adjust them to
the manufacturer's specifications. The
trailer brakes must meet local and federal
regulations. The rating for the tow vehicle's braking
system operation is at the gross vehicle
weight rating, not the gross combined
weight rating.
Trailer Lamps
WARNING
Never connect any trailer lamp wiring
to the vehicle's tail lamp wiring; this
may damage the electrical system
resulting in fire. Contact your authorized
dealer as soon as possible for assistance
in proper trailer tow wiring installation.
Additional electrical equipment may be
required. Trailer lamps are required on most towed
vehicles. Make sure all running lights, brake
lights, turn signals and hazard lights are
working.
Before Towing a Trailer
Practice turning, stopping and backing up
to get the feel of your vehicle-trailer
combination before starting on a trip.
When turning, make wider turns so the
trailer wheels clear curbs and other
obstacles.
When Towing a Trailer
•
Check your hitch, electrical connections
and trailer wheel lug nuts thoroughly
after you have traveled 50 miles (80
kilometers).
• When stopped in congested or heavy
traffic during hot weather, place the
gearshift in position
P or position N to
aid engine and transmission cooling
and to help air conditioning
performance.
• Turn off the speed control with heavy
loads or in hilly terrain. The speed
control may turn off automatically
when you are towing on long, steep
grades.
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Front of vehicle
Verify running lights are clean and unbroken.
Inspect for any missing or loose fasteners, power steering
fluid leaks and damage to power steering hoses.
Steering gear
Verify connecting links, arms and rods are not worn or cracked.
Steering linkage
Verify joints, sockets and boot seals are not worn or loose.
Verify cotter keys, nuts and bolts are not loose or missing.
Inspect front and rear tow hooks for damage or loose
mounting. This is particularly important on vehicles that use
them frequently.
Tow hooks Front suspension
Inspect for missing, broken or shifted leaves, or leaves that
may be in contact with (or nearly contacting) a tire, rim, brake
drum, frame or body component.
Springs
Note: Never apply grease to spring pads.
Make sure there the following items are properly tightened
and that there are no cracks, breaks, wear, damage to spring
hangers, bolts, bushings, axle mounting bolts, and nuts.
Spring mounts
Inspect for any cracks, leaks, or missing or broken bolts or
bushings.
Shock absorbers
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Tractor-coupling system
Inspect for loose or missing mounting brackets, clamps, bolts
or nuts. Verify solid attachment of both fifth wheel and the
slide mounting.
Mounting bolts
Inspect for cracks or breaks in the platform structure.
Platform
Verify engagement of the safety latch.
Safety latch
Verify the safety latch is in the engaged position, and that
any safety latch is in place.
Release arm
Verify the kingpin is not bent or worn, the apron lies flat on
the fifth-wheel skid plate and that the visible part of the apron
is not bent, worn, cracked or broken.
Kingpin and apron Rear suspension
Inspect for missing, broken or shifted leaves, or leaves that
may be in contact with (or nearly contacting) a tire, rim, brake
drum, frame or body component.
Springs (if equipped)
Inspect for any cracked or broken spring hangers; broken
missing or loose bolts; missing or damaged bushings; broken,
loose or missing axle mounting parts.
Spring mounts (if
equipped)
Verify torsion arm is not cracked, broken or missing.
Torsion arm and shock
absorbers
Inspect the shock absorber for cracks or leaks. There should
be no missing or broken mounting bolts or worn bushings.
Inspect for missing, broken or leaking components.
Air suspension (if
equipped) Inspect for any cracked, broken or loose bolts; missing or
damaged bushings; broken, loose or missing axle mounting
parts.
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AXLE INSPECTION
Front Axle
Maintaining the front axle alignment to
specifications is very important. A qualified
technician should check and maintain the
alignment.
Regular inspections should include:
•
Toe-in inspection and adjustment (if
necessary), particularly with radial
tires.
• Checking for proper tightness of axle
mounting U-bolt nuts, attaching or
mounting bolts and nuts.
• Checking the axle for damage, binding,
worn parts and adequate lubrication.
• Checking the kingpins for excessive
wear. Also, perform this check during
other scheduled maintenance, for
example as tire rotation or service,
wheel bearing service and alignment.
See the workshop manual for proper
procedures.
Toe-in
It is essential to maintain correct toe-in
and tire pressure for optimum tire wear.
Inspecting steer axle tires in the first
3,000– 10,000 mi (5,000– 16,000 km)
generally shows if tires are wearing
normally.
Rapid outside shoulder wear on both tires
indicates too much toe-in.
Rapid inside shoulder wear on both tires
indicates too much toe-out.
In P&D-type service, there can be a
left-to-right steer tire tread life differential
up to 40% depending on routes and other
variables. Follow the tire manufacturer's
recommended cold inflation pressure for
the tire size, load range (ply rating) and
steer axle loading typical for their operation
(each steer axle tire equals ½ steer axle
loading).
Special applications may warrant a setting
based on experience with the type of tire
operating loads and conditions. Radial tires
are more sensitive to toe-in setting than
bias ply tires. Fine tuning school bus
alignment to line-haul truck standards
does not drastically improve tire tread life.
STEERING SYSTEM
INSPECTION
WARNING
Failure to maintain the steering
system in proper condition can cause
reduced steering ability resulting in
property damage, personal injury or death. Note:
Have any steering problems
immediately corrected by a qualified service
technician.
Ask your service technician to examine the
steering mechanism. Only minor
adjustments may be necessary.
Regular inspections should include:
• Checking the tie rod, drag link end
clamp bolts and ball joints for proper
tightness.
• Checking for installation and spread of
cotter pins and tightness of nuts at
both ends of the tie rod and drag link.
• Checking that the pitman arm (steering
arm at steering gear) mounting is tight
and locked. Check system for leaks or
hose chafing. Repair immediately, if
necessary.
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•
Maintaining proper steering gear and
power steering pump lubricant levels.
• Checking steering column joint bolts
and steering linkage, particularly for
body-to-chassis clearance.
Steering Column Joint Bolts
As a good maintenance practice, check
steering column joint bolt tightness every
60,000 mi (96,000 km) or annually,
whichever occurs first. Do not overtighten
the bolts.
Hydraulic System
Whenever draining and refilling the power
steering's hydraulic system for any reason,
bleed air from the system before returning
the vehicle to service. Failure to bleed the
hydraulic system properly can result in
degradation of power system performance.
Consult an authorized dealer who is aware
of the proper procedures for filling and
bleeding the system.
SUSPENSION SYSTEM
INSPECTION
Note: Do not adjust air suspension height
to any setting other than the specified
setting. Altering the height setting changes
the driveline angle and may result in
unwarrantable component damage, such
as transmission component damage.
Verify drive axle air suspension height and
height control valve performance at engine
oil change intervals.
Periodically check:
• Condition of spring leaves for evidence
of fatigue, bending or breakage.
• Condition of suspension mounting
brackets and bushings.
• Torque rod mounting fasteners for
tightness. •
For proper suspension alignment.
Maintain proper alignment at all times.
• U-bolts. After the chassis has been
operating under load for
1,000 mi
(1,600 km) or six months (whichever
comes first), the U-bolt nuts must be
re-torqued. Re-torque the U-bolt nuts
every
37,000 mi (60,000 km)
thereafter. Clean and lubricate the
U-bolt and nut threads and seats to
make sure a like new condition when
re-torqueing. See
Spring U-Bolt
Check (page 224).
FRAME AND TOW HOOK
INSPECTION
Your vehicle's chassis is manufactured
with frame rails of either HSLA steel or
heat-treated steel. Handle each in a
specific manner to make sure maximum
service life. Consult the service manual or
an authorized dealer before attempting
frame repair or modification.
It is important, particularly on vehicles that
use tow hooks frequently, to inspect the
front and rear tow hooks for damage or a
loose mounting.
REAR AXLE FLUID CHECK
Your rear axle may have an optional
synthetic lubricant that allows the use of
extended service intervals. A tag on the
filler plug identifies the use of the synthetic
lubricant.
Only use a lubricant that meets
manufacturer specifications. Only use a
lubricant that meets manufacturer
specifications. Use of a non-approved rear
axle lubricant may cause internal axle
component damage. See Capacities and
Specifications
(page 258).
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Checking the Fluid Level
1. Park your vehicle on level ground.
2. Set the parking brake and shift into
position neutral (N) or park (P). Turn
the engine off.
3. Clean any dirt from around the axle filler plug.
4. Remove the filler plug and inspect the lubricant level. It should be at the
bottom of the filler plug opening.
5. Add lubricant, if necessary, through the
filler plug opening.
6. Clean and install the filler plug securely.
Changing the Fluid
Note: Drain the rear axle while the lubricant
is warm.
1. Park your vehicle on level ground.
2. Set the parking brake and shift into position neutral (N) or park (P). Turn
the engine off.
3. Clean any dirt from around the axle filler and drain plugs.
4. Remove the filler and drain plugs. Drain
the lubricant into a suitable container.
Dispose of all used automotive fluids
in a responsible manner following your
local authorized standards.
5. Clean and install the drain plug securely.
6. Add lubricant through the filler plug opening.
7. Clean and install the filler plug securely.
SPRING U-BOLT CHECK
Check and tighten the U-bolt nuts after
your vehicle has been operated under load
for 1,000 mi (1,600 km) or six months,
whichever occurs first. Thereafter, install new U-bolt nuts and
washers every
36,000 mi (58,000 km).
Check and tighten the U-bolt nuts with
your vehicle at curb height and unloaded.
Inspect the U-bolt threads for rust and
debris. Clean the threads if contaminated.
U-bolt Nut Torque
Front Axle
Note: Check and tighten the U-bolt nuts
evenly using a criss-cross pattern in the
following stages. lb.ft (Nm)
Stage
40 (60)
1.
90 (125)
2.
170 (225)
3.
240 (325)
4.
Rear Axle
Note: Check and tighten the U-bolt nuts
evenly using a criss-cross pattern in the
following stages. lb.ft (Nm)
Stage
60 (75)
1.
90 (125)
2.
170 (225)
3.
240 (325)
4.
320 (440)
5.
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Cooling system....................................................
231
Engine...................................................................... 231
Fuel system........................................................... 231
General.................................................................. 230
Miscellaneous...................................................... 231
Removing Vehicle From Storage................... 231
Tires........................................................................\
.. 231
Ventilation See: Climate Control........................................... 70
VIN See: Vehicle Identification Number............256
Voice Control...................................................45
W
Warning Lamps and Indicators................58 Anti-Lock Braking System................................ 58
Automatic Regeneration Control................... 58
Battery...................................................................... 58
Brake System......................................................... 58
Check Fuel Cap..................................................... 58
Check Suspension............................................... 58
Cruise Control........................................................ 58
Diesel Exhaust Fluid (Diesel Engine Only).................................................................... 58
Diesel Particulate Filter (Diesel Engine Only).................................................................... 59
Direction Indicator............................................... 59
Door Ajar.................................................................. 59
Electronic Locking Differential........................ 59
Engine Oil Pressure............................................. 59
Exhaust Brake On................................................ 59
Fasten Seatbelt.................................................... 59
High Beam.............................................................. 59
Hydromax............................................................... 59
Low Fuel Level (Gasoline Engine Only).................................................................... 59
Parking Brake Warning....................................... 59
Powertrain Malfunction/Reduced Power/Electronic Throttle Control
(Gasoline Engine Only)................................ 60
Service Engine Soon........................................... 60
Traction Control (Diesel Engine Only).........60
Trailer Anti-Lock Brake System (ABS).................................................................. 60
Transmission Tow/Haul.................................... 60
Two Speed Axle................................................... 60
Wait to Start (Diesel Engine Only)................60 Water in Fuel...........................................................
61
Washer Fluid Check
.....................................201
Washers See: Cleaning the Exterior.............................. 226
See: Wipers and Washers................................. 46
Waxing..............................................................227
Wheel Nuts See: Changing a Road Wheel....................... 248
Wheels and Tires
.........................................233
Technical Specifications................................. 250
Windows and Mirrors...................................50
Windshield Washers
.....................................46
Windshield Wipers........................................46
Wiper Blades See: Checking the Wiper Blades.................205
Wipers and Washers.....................................46
379
F-650/750 (TBC) , enUSA, First Printing Index