Brake Master Cylinder: Testing and Inspection

1. Check for cracks in the master cylinder body or for 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 brake pedal linkage.
a. If this is satisfactory, disassemble the master cylinder and check for a swollen master cylinder reservoir diaphragm or swollen primary or secondary piston seal(s).
b. If swollen primary or secondary seal(s) are found, substandard or contaminated brake fluid should be suspected.
c. If contaminated, all components should be disassembled and cleaned. All rubber components, including those in the combination valve, brake pressure modulator valve, disc brake calipers and rear wheel cylinders, should be replaced and all brake pipes flushed.