What is a common cause of low fluid level in the master cylinder?

The reasoning behind selecting worn brake pads and linings as a common cause of low fluid level in the master cylinder is tied to the design and function of the braking system. When brake pads and linings wear down, they require more brake fluid to engage the braking mechanism effectively. As the pads compress and the linings wear, the calipers move out to compensate for the reduced thickness. This movement leads to a displacement of brake fluid from the master cylinder into the brake system, causing a noticeable drop in fluid levels.

Regularly monitoring brake fluid levels is essential, as low fluid can indicate wear in the braking system or potential leaks elsewhere. Thus, worn brake pads and linings directly contribute to reducing the volume of fluid present in the master cylinder due to their interaction with the hydraulic system of braking.

While faulty brake hoses can also cause fluid loss, they typically present with leaks rather than just a drop in fluid level. Loose screws on the master cylinder could lead to fluid leaks but are not a common cause of a general low fluid level. Old brake fluid, although it can lead to performance issues, does not directly correlate with the physical displacement of fluid like worn brake components do.