🚗 Classic Fault — Mercedes-Benz W115 (1968–1976)
Brake fluid contamination — moisture absorption
💰 Estimated Repair Cost
$10 – $30 USD
Parts and labour estimate
🔧 Tools Required
Brake bleeder, moisture test strips
📋 Overview
Brake fluid absorbs moisture over time. Old brake fluid can have a boiling point reduced from 260C to below 170C. Under hard braking this causes vapour lock and spongy brakes.
🩺 Symptoms
- Spongy brake pedal after hard use
- pedal going to floor after repeated stops
- fading brakes
🔍 Possible Causes
- Moisture-contaminated brake fluid
- rubber hoses swollen internally
🛠️ Diagnosis Steps
Test brake fluid with moisture test strips. Fluid should not contain more than 2% water.
✅ Most Confirmed Fix
Completely flush brake system with fresh DOT 4 fluid.
90% of users confirm this fix worked (45 reports)
🏷️ Parts Needed
DOT 4 brake fluid
🔗 Other Mercedes-Benz W115 Faults
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