Cardone Select 13-21050 New Brake Master Cylinder Cardone Select Engineered (CSE) Technology ensures that all master cylinders meet or exceed O.E. form, fit and function All cylinder bores are micro-finished to precise specifications to dramatically reduce wear and promote long service life Castings are protected by an anodized coating that resists corrosion and pitting EPDM seals and O-rings meet O.E. quality standards to ensure reliable, leak-free performance Life-cycle testing ensures that every master cylinder exceeds S.A.E. stroke requirements Check booster for a defective push rod seal. If this seal is bad, it could drain the brake fluid out of the master cylinder. The master cylinder is working correctly. Check for a faulty brake booster or frozen wheel cylinder/caliper. Check booster for a defective push rod seal. If this seal is bad, it could drain the brake fluid out of the master cylinder.