What can result from having air in the brake lines?

Having air in the brake lines can significantly impact brake performance, leading to reduced responsiveness. When air is present in the hydraulic brake system, it creates compressibility, which means that when the brake pedal is pressed, the force from the pedal is less effectively transmitted through the brake fluid to the brake components. This can result in a spongy or soft brake feel and an increase in the distance required to stop the vehicle, making the brakes less effective.

In hydraulic brake systems, the ideal scenario is to have only brake fluid in the lines to ensure that the hydraulic pressure builds up efficiently and promptly. The presence of air disrupts this process, leading to the conclusion that the brakes may become less responsive.