GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1997 🢒 GMC P42 Commercial Chassis 🢒 Brakes 🢒 Air Brakes 🢒 Air Brake Reservoir Draining

Daily Maintenance Draining

    Object Number: 32151 Size: SH
  1. Water and contaminants should be drained from the air reservoirs daily unless a moisture ejector valve is installed. Daily draining is not necessary on reservoirs with the moisture ejector valve. Moisture ejector valves automatically drain water and contaminants from the system.

    2. Start the engine. Charge the system with air.

  2. Loosen the drain cock on the bottom of the reservoir until it opens.
  3. After the water and contaminants stop draining, tighten the drain cock.

Complete Service Draining

    Object Number: 32151 Size: SH
  1. Block the vehicle's wheels.
  2. Set the parking brake.
  3. Drain the reservoir.
    4. • On reservoirs with a drain cock, loosen the drain cock until the valve opens.
    • On reservoirs with a moisture ejector valve, push up on the wire on the bottom of the moisture ejector valve and hold it until all the air is drained.