🚗 Classic Fault — Mercedes-Benz (1968–1976)
W114 brake master cylinder internal bypass
💰 Estimated Repair Cost
$40 – $120 GBP
Parts and labour estimate
🔧 Tools Required
Brake bleeding kit
📋 Overview
The master cylinder internal seals harden and allow fluid to bypass, giving a slow sinking pedal under sustained pressure.
🩺 Symptoms
- Pedal slowly sinks to floor when held
- no external fluid leak
- pedal feels normal on quick pumping
🔍 Possible Causes
- Worn master cylinder primary cup seal
- contaminated fluid softening seals
- old fluid with moisture
🛠️ Diagnosis Steps
Hold brake pedal with firm constant pressure for 30 seconds — if it sinks more than 1 inch, master cylinder is bypassing
✅ Most Confirmed Fix
Master cylinder replacement and full fluid flush
87% of users confirm this fix worked (20 reports)
🩺 Related Symptoms
🔗 Other Mercedes-Benz Faults
Own a Mercedes-Benz ?
Share your experience with this fault — or report a different issue. Your knowledge helps other classic car owners worldwide.