What needs to be checked manually to remove from vehicles that lack automatic air tank drains?

Vehicles without automatic air tank drains need to be checked manually to remove water and oil. Over time, moisture and oil can accumulate in the air tanks of air brake systems. These contaminants need to be drained regularly to maintain the proper functioning of the brakes and prevent potential issues. Manual draining involves opening the drain valves on the air tanks and allowing the water and oil to be released from the system.