UNDER HOOD OVERVIEW - 6.7L DIESEL
Windshield washer fluid reservoir. See Washer Fluid Check (page 206).
A
Secondary Cooling System Reservoir. See Engine Coolant Check (page 196).
B
Engine coolant reservoir. See
Engine Coolant Check (page 196).
C
Automatic transmission fluid dipstick. See
Automatic Transmission Fluid
Check (page 204).
D
Secondary fuel filter. See
Draining the Fuel Filter Water Trap (page 207).
E
Engine oil separator. See
Changing the Engine Oil and Oil Filter (page 194).
F
Brake fluid reservoir. See
Brake Fluid Check (page 205).
G
Engine compartment fusebox. See
Fuses (page 167).
H
Power steering fluid reservoir. See
Power Steering Fluid Check (page 206).
I
Air brake compressor. See
Brake System Inspection (page 222).
J
Engine oil filler cap. See
Engine Oil Check (page 192).
K
Engine oil dipstick. See
Engine Oil Dipstick (page 192).
L
Air cleaner assembly. See
Changing the Engine Air Filter (page 213).
M
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UNDER HOOD OVERVIEW - 6.8L
Windshield washer fluid reservoir. See Washer Fluid Check (page 206).
A
Engine coolant reservoir. See
Engine Coolant Check (page 200).
B
Automatic transmission fluid dipstick. See
Automatic Transmission Fluid
Check (page 204).
C
Brake fluid reservoir. See
Brake Fluid Check (page 205).
D
Engine compartment fusebox. See
Fuses (page 167).
E
Power steering fluid reservoir. See
Power Steering Fluid Check (page 206).
F
Engine oil dipstick. See
Engine Oil Dipstick (page 192).
G
Engine oil filler cap. See
Engine Oil Check (page 193).
H
Air cleaner assembly. See
Changing the Engine Air Filter (page 216).
I
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AUTOMATIC TRANSMISSION
FLUID CHECK
The transmission does not consume fluid.
However, the fluid level should be checked
if the transmission is not working properly,
for example if the transmission slips, shifts
slowly or if there are signs of fluid loss.
The transmission fluid and filter on your
vehicle must be replaced at the specified
service interval. See Scheduled
Maintenance (page 322).
Automatic transmission fluid expands
when warmed. To check the fluid level
consistently and accurately, do the
following:
1. Drive the vehicle until it reaches normal
operating temperature. This may take
up to
20 mi (30 km).
2. Make sure that your vehicle is on level ground.
3. With the engine running, parking brake
engaged and your foot on the brake
pedal, move the gearshift lever through
all of the gear ranges. Allow sufficient
time for each gear to engage.
4. Make sure the parking brake is on. Make
sure the transmission is in park (P) or
neutral (N) and leave the engine
running.
5. Open the hood. See
Opening and
Closing the Hood (page 188).
6. Remove the dipstick and wipe it with a clean, lint-free cloth. See
Under
Hood Overview (page 191).
7. Replace the dipstick and remove it again to check the fluid level.
8. If the fluid level is correct, replace the dipstick and make sure it is fully seated.
Note: If the fluid level is between the
maximum and minimum marks, the fluid
level is acceptable. Do not add fluid. Transmission Fluid Level
Low Fluid Level
If the fluid level is at or below the minimum
mark, add fluid immediately. See
Capacities and Specifications
(page
261).
Note: If there is no indication of fluid on the
dipstick, have your vehicle checked
immediately.
Correct Fluid Level Make sure that the fluid level is between
the maximum and minimum marks.
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High Fluid Level
Do not add fluid further than the maximum
mark. Fluid levels above the maximum
mark may cause shift or engagement
concerns and possible damage.
Note:
High fluid levels can be caused by an
overheating condition.
Adding Transmission Fluid
Do not use supplemental transmission
fluid additives, treatments or cleaning
agents. The use of these materials may
affect transmission operation and result
in damage to internal transmission
components and could lead to
transmission damage that may not be
covered by the vehicle Warranty.
Use only recommended transmission fluid
that meets our specifications. See
Capacities and Specifications (page
261).
Note: Use of a non-approved automatic
transmission fluid may cause internal
transmission component damage.
If necessary, add fluid in
8 fl oz (250 ml)
increments through the filler tube until the
level is correct.
If an overfill occurs, excess fluid should be
removed, have your vehicle checked as
soon as possible. BRAKE FLUID CHECK WARNING:
Do not use any fluid
other than the recommended brake fluid
as this will reduce brake efficiency. Use
of incorrect fluid could result in the loss
of vehicle control, serious personal injury
or death. WARNING:
Only use brake fluid
from a sealed container. Contamination
with dirt, water, petroleum products or
other materials may result in brake
system damage or failure. Failure to
adhere to this warning could result in the
loss of vehicle control, serious personal
injury or death. WARNING:
Do not allow the fluid
to touch your skin or eyes. If this
happens, rinse the affected areas
immediately with plenty of water and
contact your physician. WARNING:
A fluid level between
the MAX and MIN lines is within the
normal operating range and there is no
need to add fluid. A fluid level not in the
normal operating range could
compromise the performance of the
system. Have your vehicle checked
immediately.
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Once a year, inspect the entire brake
system:
•
Rubber components for deterioration.
A qualified technician should inspect
these components and replace them
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.
Periodically inspect parts such as air brake
chamber diaphragm, air compressor and
air cleaner. Replace any parts if you can
consider them unserviceable.
Air Dryer
Climactic conditions affect performance
of desiccant or after-cooler type air dryers.
You must establish a maintenance
schedule for each specific operation.
The use of an air dryer on a vehicle does
not eliminate the need to drain the air
reservoirs periodically.
Inspect for moisture in the air system by
opening reservoirs, draincocks or valves
and checking for presence of water. The
presence of small amounts of water due
to condensation is normal and is not an
indication that the dryer is not functioning
properly. Replace or rebuild the desiccant cartridge
when you determine that the desiccant is
contaminated and does not have adequate
water absorption capacity. The desiccant
change interval may vary. A general
recommendation is to replace the
desiccant every 12 months (yearly). If
experience has shown that extended or
shortened life has resulted for a particular
installation, then the yearly interval can be
increased or decreased accordingly.
Draining the Air Brake Reservoir
WARNING: Failure to drain air
brake reservoirs can result in a reduction
or loss of braking ability due to fluid
accumulation in the reservoir and/or
possible freeze-up during cold weather.
Completely drain all the air brake reservoirs
daily by opening the draincock at the ends
of the tanks. (Where accessible.
Pull-chains are used when the drains are
undercab or otherwise inaccessible.) Close
the draincock after draining. Manually drain
any air tanks equipped with automatic
moisture ejector valves, as required, to
maintain a dry air system. Contact an
authorized dealer if you are unsure of the
air reservoir locations or the draining
procedure.
Hydraulic Brakes
Establish a regular schedule for periodic
cleaning, lubrication and adjustment
inspection based on vehicle use. Exact
maintenance intervals are difficult to
predetermine due to vehicle applications
and operating conditions. If you are
uncertain of the proper schedule for your
vehicle, contact an authorized dealer.
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Regular inspections should include:
•
Checking the brake lining (every service
interval). Establish inspection intervals
that provide for lining replacement
before damage to the disc occurs.
Excessive lining wear may expose the
backing plate to the disc causing
scoring of the disc faces. A qualified
technician should perform this
inspection and keep to instructions
provided by the service manual.
Hydraulic brake systems are
power-assisted. There is a great
reduction in braking capabilities
without engine assist.
• Proper fluid level. The level should be
at the bottom edge of the ring on each
reservoir fill port. Do not fill the master
cylinder to the top of the reservoir. If
fluid level requires attention to
maintain a proper master cylinder level,
this is an indication of either severe
operation (pad wear) or fluid leakage.
A more frequent and thorough brake
inspection is required.
• Brake lines, hoses and fittings. Repair
or replace brake line tubes, hoses or
fittings as required. Inspect these
components every 4,000 mi
(6,000 km) for the following.
• Lines for kinks, dents, corrosion or
rupture.
• 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.
• All connections for leaks. Driveline Parking Brake WARNING:
Use wheel chocks and
exercise caution when inspecting under
the vehicle. A vehicle roll-away could
result in property damage, personal injury
or death.
A qualified technician should adjust the
parking brake and keep to the instructions
in the service manual.
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.
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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 228).
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 261).
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.
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Cooling system
•
Protect against freezing temperatures.
• When removing your vehicle from
storage, check coolant fluid level.
Confirm that there are no cooling
system leaks and that fluid is at the
recommended level.
Battery
• Check and recharge as necessary. Keep
connections clean.
• If storing your vehicle for more than 30
days without recharging the battery,
we recommend that you disconnect
the battery cables to maintain battery
charge for quick starting.
Note: It is necessary to reset memory
features if battery cables are disconnected.
Brakes
• Make sure the brakes and parking brake
release fully.
Tires
• Maintain recommended air pressure.
Miscellaneous
• Make sure all linkages, cables, levers
and pins under your vehicle are covered
with grease to prevent rust.
• Move vehicles at least 25 ft (7.5 m)
every 15 days to lubricate working parts
and prevent corrosion.
Removing Vehicle From Storage
When your vehicle is ready to come out of
storage, do the following:
• Wash your vehicle to remove any dirt
or grease film build-up on window
surfaces.
• Check windshield wipers for any
deterioration. •
Check under the hood for any foreign
material that may have collected
during storage such as mice or squirrel
nests.
• Check the exhaust for any foreign
material that may have collected
during storage.
• Check tire pressures and set tire
inflation per the Tire Label.
• Check brake pedal operation. Drive
your vehicle
15 ft (4.5 m) back and
forth to remove rust build-up.
• Check fluid levels (including coolant,
oil and gas) to make sure there are no
leaks, and fluids are at recommended
levels.
• If you remove the battery, clean the
battery cable ends and check for
damage.
Contact an authorized dealer if you have
any concerns or issues.
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