Air Dryer Inspection

4700 mm 42.02.001
  1. Park the vehicle on a level surface and apply the parking brakes. Shut down the engine. Chock the tires.
  2. Completely drain all air reservoirs. Air pressure gauges should read 0 psi (0 kPa).
  3. Close the drain cocks on all reservoirs.
  4. Start the vehicle and allow the air system pressure to build while the engine idles.

    5. Note: Some compressors may need to run above idle to build system air pressure in a reasonable time. If air pressure build-up is extremely slow after two to three minutes, raise the engine speed to 1000 to 2000 rpm.

  5. Place your hand under the air dryer purge valve, located at the base of the dryer; see Fig.. You should feel a light air flow that will continue until the air compressor unloads.

    Fig. 1, Air Dryer Inspection

  6. On the System Saver Twin only, if the compressor continues to run, after 50 to 60 seconds you will feel a "mini-purge", or exhaust of air, as the dryer switches cartridges. This is normal and will recur every 50 to 60 seconds as long as the compressor is running.
  7. When the air system reaches "cut-out" pressure, the dryer will purge completely. After this, the dryer will not exhaust any air until the compressor starts up again.
  8. Shut off the engine and apply a soap solution to each connection that contains pressurized air. If soap bubbles do not appear, connections are sealed properly. If soap bubbles appear, drain all reservoirs and remove the leaking connection. Inspect it for damaged threads or cracks, and replace as necessary. Apply pipe sealant or teflon tape to the connection before re-installing it. Repeat the process until all connections are properly sealed.
Note:
Parent topic: Brakes
Document Number: 0000120992
Manual Publication Date: 2024-05-23
Topic Publication Date: 2024-10-31