If air in the brake system is not the cause of spongy brake action, what is the next likely cause?

A spongy brake action typically indicates a problem within the brake system that affects the hydraulic pressure or the efficiency of braking components. If air in the brake lines has been ruled out, the next most probable cause is deteriorated flexible hoses.

Flexible hoses can wear out over time due to exposure to heat, humidity, and the harsh chemicals that can be present in brake fluid. As hoses age, they can internally collapse or develop cracks, leading to a decrease in pressure, which can cause a spongy feel when the brake pedal is depressed. When the brake pedal is pressed, instead of transferring fluid pressure effectively to the brake calipers or drums, the compromised hose may allow the fluid to expand within the hose itself, resulting in a loss of effective braking force.

While other components like deteriorated brake linings, low fluid levels in the reservoir, or a faulty master cylinder could contribute to brake performance issues, they are less likely to specifically produce a spongy feel compared to the action of a failing flexible hose. Deteriorated linings would typically cause reduced stopping power or increased stopping distances, low fluid levels would trigger an illuminated warning light, and a faulty master cylinder would more likely lead to a complete brake failure rather than just a