Final answer:
When air enters the brake system, it reduces the brake efficiency by causing delays in the braking action and making the pedal feel spongy. Air needs to be bled out of the system to restore proper brake function.
Step-by-step explanation:
When air gets into the brake system, it reduces the efficiency of the brakes. This is because air is compressible, unlike brake fluid which is not. When the brake pedal is pressed, the air in the system will compress first before any force is exerted on the brake pads or shoes. This delays the braking action, resulting in reduced efficiency.
The presence of air also causes a spongy feel in the brake pedal, making it difficult to modulate the braking force effectively. It can also lead to uneven braking and potential loss of control.
To solve this issue, the air in the brake system needs to be bled out. This involves opening the bleeder valves on the brake calipers or wheel cylinders and allowing the air to escape while replenishing the system with fresh brake fluid.