YOUR VEHICLE’S AIR SYSTEM PART 8: MAINTENANCE AND SERVICE
– 190 – Y53-6032 (R05/10)
CAUTION:
Don’t use penetrating oil, brake fluid,
or wax-based oils in the air system. These fluids
may cause severe damage to air system compo-
nents
.
• Maintain the air compressor to prevent excessive oil
by-pass. See your shop manual for maintenance
details.
• Replace worn seals in valves and air motors as they
are needed.
Air Dryer
WARNING! Use of incorrect air dryer could
cause air system failure, leading to loss of vehi-
cle control and serious personal injury or death.
If your vehicle is equipped with a Bendix AD-IS
air dryer, it is important that future replacements
be identical or similar in design.
Any deviation from the Bendix AD-IS type air
dryer would require changes to the vehicle air system.
Some vehicles use a dual air system consisting of a wet
tank, forward dry tank, and rear dry tank. The dry tanks
have a single-check valve in the tank inlet. The check
valves prevent a complete loss of air in the event of an air
system failure (tank or hose failure). This ensures a con-
trolled stop (with reduced braking capability). Other vehi-
cles use a Bendix AD-IS air dryer which eliminates the
need for a wet tank and check valves in the dry tanks.
NOTE: A small amount of oil in the system may be
normal and should not, by itself, be considered rea-
son to replace a desiccant cartridge; oil-stained
desiccant can function adequately.
Every 900 operating hours or 30,000 miles/48,000 km or 3
months, check for moisture in the air brake system by
opening reservoirs, drain valves, or valves and checking
for the presence of water. A tablespoon of water in a res-
ervoir would point to the need for a desiccant cartridge
change. However, the following should be considered first:
• Air usage is exceptionally high/abnormal for a high-
way vehicle. This may be due to accessory air
demands or some other unusual air requirement that
doesn’t allow the compressor to load/unload in a nor-
mal fashion or it may be due to excessive leaks in the
air system.
• When more than a 30-degree F (17-degree C) range
of temperature occurs in one day, small amounts of
water can accumulate in the air brake system due to
condensation. Under these conditions, the presence
Y53-6032.book Page 190 Monday, May 24, 2010 3:37 PM
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