Master Cylinder Test

Master Cylinder Test
These checks will not determine all master cylinder malfunctions. Refer to Diagnostic System Check - Hydraulic Brakes to help isolate a problem if it is not found here.
^ 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 normal.
^ 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.