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•Maintain engine coolant (antifreeze) concentration at a
minimum of 50% OAT coolant (conforming to
MS.90032) and distilled water for proper corrosion pro-
tection of your engine which contains aluminum com-
ponents.
• Make sure that the coolant expansion bottle overflow
hoses are not kinked or obstructed.
• Keep the front of the radiator clean. If your vehicle is
equipped with air conditioning, keep the front of the
condenser clean.
• Do not change the thermostat for Summer or Winter
operation. If replacement is ever necessary, install ONLY
the correct type thermostat. Other designs may result in
unsatisfactory engine coolant (antifreeze) performance,
poor gas mileage, and increased emissions.
Brake System
In order to assure brake system performance, all brake
system components should be inspected periodically. Refer
to the “Maintenance Plan” in this section for the proper
maintenance intervals.
WARNING!
Riding the brakes can lead to brake failure and possi-
bly a collision. Driving with your foot resting or riding
on the brake pedal can result in abnormally high brake
temperatures, excessive lining wear, and possible
brake damage. You would not have your full braking
capacity in an emergency.
Fluid Level Check — Brake Master Cylinder
The fluid level of the master cylinder should be checked
when performing under the hood service or immediately if
the brake system warning lamp indicates system failure.
The brake master cylinder has a translucent plastic reser-
voir. On the outboard side of the reservoir, there is a
“MAX” mark and a “MIN” mark. The fluid level must be
kept within these two marks. Do not add fluid above the
MAX mark because leakage may occur at the cap.
With disc brakes the fluid level can be expected to fall as
the brake linings wear. However, an unexpected drop in
fluid level may be caused by a leak and a system check
should be conducted.
386 SERVICING AND MAINTENANCE
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9. Reinsert the dipstick. Check for leaks. Release the park-ing brake.
NOTE: To prevent dirt and water from entering the trans-
mission after checking or replenishing fluid, make sure that
the dipstick cap is properly reseated. It is normal for the
dipstick cap to spring back slightly from its fully seated
position, as long as its seal remains engaged in the dipstick
tube.
Fluid And Filter Changes
Refer to the “Maintenance Plan” for the proper mainte-
nance intervals.
In addition, change the fluid and filters if the fluid becomes
contaminated (with water, etc.), or if the transmission is
disassembled for any reason.
Rear Axle And 4x4 Front Driving Axle Fluid Level
For models with 9.25 in Front Axles and 11.5 in Rear Axles,
refer to “Fluids And Lubricants” in “Servicing And Main-
tenance” for further information. For normal service, peri-
odic fluid level checks are not required. When the vehicle is
serviced for other reasons, the exterior surfaces of the axle
assembly should be inspected. When checking the fluid level (4500/5500 only), the vehicle
should be in a level position. The fluid level should be ¼ in
± ¼ in (6.4 mm ± 6.4 mm) below the fill hole on the front
axle. The fluid level should be level with the bottom of the
fill hole on the rear axle.
Drain And Refill
On 4500/5500 vehicles, remove the lower bolt to drain the
axle fluid.
4500/5500 Rear Axle Plugs
1 — 4500/5500 Rear Axle Fluid Fill Plug
2 — 4500/5500 Rear Axle Fluid Drain Plug
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Refer to “Scheduled Servicing” in this chapter for the
proper maintenance intervals.
Lubricant Selection
Refer to “Fluids And Lubricants” in “Technical Specifica-
tions” for further information.
NOTE:The presence of water in the gear lubricant will
result in corrosion and possible failure of differential
components. Operation of the vehicle in water, as may be
encountered in some off-highway types of service, will
require draining and refilling the axle to avoid damage.
Limited-Slip Differentials DO NOT REQUIRE any lim-
ited slip oil additive (friction modifiers).
NOTE: Slight noise and mild shuddering may be evident
while turning a vehicle with limited slip differential on
concrete or dry pavement. These conditions should be
considered normal operation of the limited slip differential.
Transfer Case
Selection Of Lubricant
Use only the manufacturer’s recommended fluid. Refer to
“Fluids And Lubricants” in “Technical Specifications” for
further information.
Fluid Level Check
This fluid level can be checked by removing the filler plug.
The fluid level should be to the bottom edge of the filler
plug hole with the vehicle in a level position.
Drain And Refill
Refer to the “Maintenance Plan” for the proper mainte-
nance intervals.
HOISTING
A conventional floor jack may be used at the jacking
locations. Refer to the graphics that show jacking locations.
However, a floor jack or frame hoist must never be used on
any other parts of the underbody.
CAUTION!
Never use a floor jack directly under the differential
housing of a loaded truck or damage to your vehicle
may result.
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