Bendix AD-9 Air Dryers

cen mm 42.02.000

Park the vehicle on a level surface, shut down the engine, and set the parking brake. Chock the tires.
Completely drain all air reservoirs. Air pressure gauges should read 0 psi (0 kPa).

Caution: The compressor discharge line may still contain residual air pressure.

Identify, tag, and disconnect the three air lines from the end cover.
Disconnect the harness connector from the heater and thermostat assembly.
Loosen the capscrew securing the upper mounting bracket strap.
Remove the two capscrews that secure the air dryer to the lower mounting bracket. Mark the position of the mounting bracket to the end cover, and mark the capscrews to ease installation.
Remove the upper mounting bracket strap capscrew, and remove the air dryer from the vehicle.
Place the air dryer on a bench and remove the remaining 6 capscrews, 12 washers, 6 Nylok®nuts, and the air dryer housing. See Fig.. Discard the Nylok nuts. Remove the end-cover-to-housing O-ring.
Fig. 1, AD-9 Air Dryer (exploded view)
Clamp the desiccant cartridge in a vise.

Caution: Clamping the end cover or housing in a vise could seriously compromise the air dryer's ability to hold air pressure, which could cause a failure in the brake system.

Twist the end cover counterclockwise to release the cartridge from the end cover. Rotate the end cover until it completely separates from the desiccant cartridge.

Note: A substantial torque, up to 50 lbf·ft (68 N·m), may be necessary to remove the desiccant cartridge.

Inspect the condition of the O-ring seals. If they are cracked, crimped, or otherwise damaged, replace them to ensure an airtight seal. Clean the O-ring grooves of any dirt or obstruction.

Caution: Dirt or obstructions in the O-ring grooves can cause an O-ring failure that will result in an air leak.

Lubricate the O-rings with silicone or lithium grease and install them in the end cover.
Install the desiccant cartridge on the end cover. Turn the cartridge clockwise until the desiccant cartridge makes contact with the end cover.
Place the desiccant cartridge in a vise, and turn the end cover clockwise an additional 180 to 225 degrees to fully tighten the desiccant cartridge to the end cover.

Note: Desiccant cartridge torque should not exceed 50 lbf·ft (68 N·m).

Place the housing over the desiccant cartridge and align the mounting holes with the end cover.

Important: Replace, do not reuse the Nylok nuts on the air dryer cover.

Install the 6 capscrews, 12 washers, and 6 new Nylok nuts. Tighten the capscrews in a star pattern 270 to 385 lbf·in (3050 to 4350 N·cm). See Fig..

Fig. 2, End Cover to Housing Torque Pattern
Install the air dryer on the lower mounting bracket. Install the two previously marked capscrews, four washers, and two new Nylok nuts. Torque the two remaining capscrews 270 to 385 lbf·in (3050 to 4350 N·cm). Install the capscrew, two washers, and a new Nylok nut in the upper mounting bracket strap. Torque the upper mounting bracket strap capscrew 80 to 120 lbf·in (904 to 1356 N·cm).
Connect and tighten the three air lines. Connect the harness connector to the heater and thermostat assembly until the lock tab snaps in place.
Start the engine, build the air pressure, and check the air brake system for leaks. If any air leaks are present, see of the Century Class Trucks Workshop Manual for diagnosis and repair information.

Note:

Century Class Trucks Maintenance Manual

Bendix AD-9 Air Dryers

Fig. 1, AD-9 Air Dryer (exploded view)

Fig. 2, End Cover to Housing Torque Pattern