What happens if there is internal leakage in a brake master cylinder unit?

In a brake master cylinder unit, internal leakage can occur when the seals or components that maintain the integrity of the hydraulic system fail. This leakage allows brake fluid to bypass the piston, which results in reduced pressure at the brakes.

When internal leakage is present, the most notable symptom is that the brake pedal will slowly creep down under pressure. This is because, despite the driver applying force to the pedal, the hydraulics fail to maintain sufficient pressure due to the fluid escaping the system instead of being directed to the brake calipers. This creeping effect indicates that the system is not holding pressure effectively, which can lead to a decrease in braking performance and a potential safety hazard.

The other options do not directly relate to the symptoms of internal leakage. For example, a quickened response of the brakes would imply that the system is functioning properly, addressing the exact opposite effect. Pulling to one side might suggest uneven braking force or issues with the brake caliper or pads, rather than internal leakage. Finally, locked brakes are indicative of other problems, such as an issue with the caliper or brake lines, not the gradual loss of pressure caused by a leaking master cylinder.