🚗 Classic Fault — Mercedes-Benz W115 (1968–1976)
Ethanol fuel damage to carburetor soft parts
💰 Estimated Repair Cost
$30 – $90 USD
Parts and labour estimate
🔧 Tools Required
Carb rebuild tools
📋 Overview
Modern pump petrol containing E10 attacks the original rubber and fibre components in the Zenith 35/40 INAT carburetors. Diaphragms swell and distort, gaskets expand, and float bowl seals fail.
🩺 Symptoms
- Multiple carburetor faults simultaneously
- recently rebuilt carb failing quickly
- rubber parts swollen
🔍 Possible Causes
- Ethanol attacking original carb rubber parts
- swollen diaphragms
- expanding gaskets
🛠️ Diagnosis Steps
Inspect all soft parts in carburetors after running on E10. Compare to specifications.
✅ Most Confirmed Fix
Rebuild carburetors with ethanol-compatible Viton parts. Use E5 or ethanol-free fuel.
76% of users confirm this fix worked (18 reports)
🏷️ Parts Needed
Ethanol-compatible rebuild kit (Viton seals and diaphragms)
🔗 Other Mercedes-Benz W115 Faults
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