Brake Master Cylinder: Testing and Inspection

These checks will not determine all master cylinder malfunctions.
1. Check for a cracked master cylinder casting, or brake fluid around the master cylinder. Leaks are indicated only if there is at least a drop of fluid. A damp condition is not abnormal.
2. Check for binding pedal linkage and incorrect pushrod length. If both are okay, remove the master cylinder reservoir cap and check for a swollen or distorted diaphragm. If a swollen diaphragm is found, substandard or contaminated brake fluid should be suspected.