How can you test hydraulic brakes for leaking?

Testing hydraulic brakes for leaks involves assessing the performance and responsiveness of the braking system. Holding pressure on the brake pedal after pumping it multiple times is a reliable method to check for leaks. When you pump the brake pedal, you build up hydraulic pressure in the system. If there are leaks, the pedal will gradually sink towards the floor under constant pressure, indicating that hydraulic fluid is escaping from the system, either at the brake lines or at the calipers/slave cylinders.

This method is effective because it directly assesses the integrity of the hydraulic system under simulated operating conditions. Maintaining pressure while monitoring the brake pedal's response allows you to quickly identify any faults that could compromise braking performance, making it a critical step in routine vehicle maintenance and safety checks.

The other options do not provide a thorough examination of the brake system for leaks. Pressing and releasing the pedal quickly may momentarily show responsiveness but does not effectively test for leaks. Checking the brake fluid level only tells you if the fluid is low but does not confirm if there is a functioning leak. Listening for noises gives no concrete information about hydraulic integrity, as noise may result from several sources unrelated to leakage. Thus, holding pressure after pumping is the most definitive method to assess for leaks in hydraulic brakes.