AD–9

p3 mm 42.02

    Important: For vehicles equipped with an oil-coalescing air dryer desiccant cartridge, replace the cartridge once a year, regardless of mileage.

  1. Park the vehicle on a level surface, apply the parking brakes, and chock the tires.
  2. Completely drain all air reservoirs. Air pressure gauges should read 0 psi (0 kPa).

    3. Note: The compressor discharge line may still contain residual air pressure, open the line slowly.

  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 and Nylok® nuts 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 fasteners, then remove the strap and the air dryer.
  8. Place the air dryer on a bench and remove the remaining 6 bolts, 12 washers, 6 Nylok nuts, and the air dryer housing. See Fig.. Discard the Nylok nuts. Remove the end-cover-to-housing O-ring.

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

    2. Upper Mounting Bracket Strap

    3. 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. Safety 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 Tapping 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 (exploded view)

  9. Clamp the desiccant cartridge in a vise.

    10. Warning: 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, resulting in property damage, personal injury, or death.

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

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

  11. 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.
  12. Lubricate the O-rings with silicone or lithium grease 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. Important: Replace, do not reuse the Nylok nuts on the air dryer cover.

  16. Install the 6 bolts, 12 washers, and 6 new Nylok nuts. Torque the Nylok nuts in a star pattern 17 to 24 lbf·ft (23 to 33 N·m). See Fig..

    Fig. 2, AD–9 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 Nylok nuts. Torque the two remaining Nylok nuts 17 to 24 lbf·ft (23 to 33 N·m). Install the bolt, two washers, and a new Nylok nut in the upper mounting bracket strap. Torque the upper mounting bracket strap Nylok nut 80 to 120 lbf·in (900 to 1360 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 vehicle Workshop Manual for diagnosis and repair information.
Note:
Parent topic: Replacement of the Bendix Air Dryer Desiccant
Document Number: 0000113624
Manual Publication Date: 2024-05-15
Topic Publication Date: 2024-11-22