🚗 Classic Fault — Mercedes-Benz W115 (1968–1976)
Distributor cap carbon tracking
💰 Estimated Repair Cost
$10 – $25 USD
Parts and labour estimate
🔧 Tools Required
Screwdrivers
📋 Overview
Carbon tracking inside the distributor cap creates a low-resistance path between segments, causing cross-firing between cylinders. Appears as misfiring at specific RPM bands that cannot be cured by points adjustment.
🩺 Symptoms
- Misfiring at specific RPM
- particular cylinder always misfiring
- rough running not cured by points adjustment
🔍 Possible Causes
- Carbon tracking between cap segments
- moisture ingress
- cracked cap
🛠️ Diagnosis Steps
Remove cap. Hold up to light and inspect interior for grey or black lines between segments.
✅ Most Confirmed Fix
Replace distributor cap and rotor as a matched pair.
87% of users confirm this fix worked (33 reports)
🏷️ Parts Needed
Bosch distributor cap for M115
🔗 Other Mercedes-Benz W115 Faults
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