AD–9 Air Dryer

s2 m 42.01.000
  1. Park the vehicle on a level surface and apply the parking brake. Shut down the engine. Chock the tires.
  2. Completely drain all air reservoirs. Air pressure gauges should read 0 psi (0 kPa).

    3. Important: The compressor discharge line may contain residual air pressure.

  3. Identify, tag, and disconnect the three air lines from the end cover.
  4. Disconnect the harness connector from the heater and thermostat assembly.
  5. Loosen the bolt that secures the upper mounting bracket strap.
  6. Remove the two bolts that secure the air dryer to the lower mounting bracket. Mark the position of the mounting bracket to the end cover and mark the bolts to ease installation.
  7. Remove the upper mounting bracket strap bolt, and remove the air dryer from the vehicle.
  8. Place the air dryer on a bench and remove the remaining 6 bolts, 12 washers, 6 nuts, and the air dryer housing. See Fig.. Discard the nuts. Remove the end-cover-to-housing O-ring.

    1. 5/16 x 4-1/2-Inch Upper Mounting Bracket Bolt

    2. Upper Mounting Bracket Strap

    3. 5/16-Inch Lockwasher

    4. 5/16-Inch Nylok® Nut

    5. Upper Mounting Bracket

    6. Housing

    7. Nylok Nut

    8. 3/8-Inch Special Washer

    9. Desiccant Cartridge

    10. O-Ring

    11. Drain Valve

    12. Lower Mounting Bracket

    13. 3/8-Inch Bolt (long)

    14. Check Valve Assembly

    15. Purge Valve Assembly

    16. Purge Valve Capscrew

    17. Exhaust Diaphragm

    18. Purge Valve

    19. 1/4-Inch Screw

    20. Purge Valve Housing

    21. Heater and Thermostat Housing

    22. Return Spring

    23. Purge Piston

    24. 3/8-Inch Bolt

    25. End Cover

    Fig. 1, AD-9 Air Dryer

  9. Clamp the desiccant cartridge in a vise.

    10. Warning: Clamping the end cover or housing in a vise could seriously compromise the ability of the air dryer to hold air pressure, which could cause a failure in the brake system, resulting in personal injury or property damage.

  10. 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.

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

  11. Remove and discard desiccant cartridge O-rings.

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

  12. Lubricate new O-rings with grease supplied in the kit and install them in the end cover.
  13. Install the desiccant cartridge on the end cover. Turn the cartridge clockwise until the desiccant cartridge makes contact with the end cover.
  14. 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.

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

  15. Place the housing over the desiccant cartridge and align the mounting holes with the end cover.
  16. Install the 6 bolts, 12 washers, and 6 new nuts. Torque the bolts in a star pattern 270 to 385 lbf·in (3060 to 4340 N·cm). See Fig..

    Fig. 2, End Cover to Housing Torque Pattern

  17. Install the air dryer on the lower mounting bracket. Install the two previously marked bolts, four washers, and two new nuts. Torque the two remaining bolts 270 to 385 lbf·in (3060 to 4340 N·cm). Install the bolt, two washers, and a new nut in the upper mounting bracket strap. Torque the upper mounting bracket strap nut 80 to 120 lbf·in (904 to 1356 N·cm).
  18. Connect and tighten the three air lines. Connect the harness connector to the heater and thermostat assembly until the lock tab snaps in place.
  19. Start the engine, build the air pressure, and check the air brake system for leaks. If any air leaks are present, see  of the S2 Chassis Workshop Manual for diagnosis and repair information.
Note:
Parent topic: Bendix Air Dryer AD–9 or AD–IP Desiccant Replacing
Document Number: 0000121146
Manual Publication Date: 2024-05-24
Topic Publication Date: 2024-11-13