What is the correct procedure to test hydraulic brakes for leaks?

The correct procedure to test hydraulic brakes for leaks involves holding the pedal down for five seconds after pumping it. This method is effective because it allows the driver to determine if the pedal remains stable under pressure, which indicates that the hydraulic system is functioning properly without leaks.

When the brake pedal is pumped and then held, any drops in the pedal position over the five seconds indicate a possible leak within the system. If there is a leak, the brake fluid will escape, causing the pedal to travel down further than it should when pressure is maintained. A stable pedal confirms the integrity of the hydraulic brake system.

The other options do not provide a reliable assessment of the system's integrity. Simply checking after pumping, such as in the first option, does not allow for a proper assessment since it doesn't maintain sustained pressure to reveal leaks. Quickly pressing the pedal three times doesn't allow for a leak to manifest, and starting the engine to test the brake system does not specifically focus on leak detection. Therefore, maintaining the pedal's position after a few pumps is essential for an accurate evaluation of the hydraulic brakes.