🚗 Classic Fault — Mercedes-Benz W115 (1968–1976)
Brake servo vacuum hose deteriorated
💰 Estimated Repair Cost
$10 – $30 USD
Parts and labour estimate
🔧 Tools Required
Hose clamp pliers
📋 Overview
The vacuum hose connecting the servo to the intake manifold perishes, reducing or eliminating brake servo assistance. The brakes work but require significantly more pedal effort.
🩺 Symptoms
- Heavy brake pedal requiring much more force
- servo hiss when pedal pressed
🔍 Possible Causes
- Perished servo vacuum hose
- faulty non-return valve
- failed servo diaphragm
🛠️ Diagnosis Steps
With engine off, pump pedal several times. Start engine — pedal should feel noticeably lighter.
✅ Most Confirmed Fix
Replace servo vacuum hose and non-return valve.
81% of users confirm this fix worked (23 reports)
🏷️ Parts Needed
Servo vacuum hose and one-way valve
🔗 Other Mercedes-Benz W115 Faults
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