🚗 Classic Fault — Mercedes-Benz W115 (1968–1976)
Carburetor dashpot damper oil empty
💰 Estimated Repair Cost
$2 – $10 USD
Parts and labour estimate
🔧 Tools Required
Dashpot oil, small funnel
📋 Overview
The Zenith 35/40 INAT uses a dashpot damper to control the air valve opening rate. If the damper oil is low or missing, the air valve opens too quickly causing a flat spot on acceleration.
🩺 Symptoms
- Hesitation on acceleration
- flat spot especially from low RPM
- engine stumbles then clears
🔍 Possible Causes
- Empty or low dashpot oil
- wrong viscosity oil used
🛠️ Diagnosis Steps
Unscrew dashpot cap. Check oil level — should be 0.5cm below top of dashpot tube.
✅ Most Confirmed Fix
Refill dashpot to correct level with 10W-30 engine oil.
91% of users confirm this fix worked (42 reports)
🔗 Other Mercedes-Benz W115 Faults
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