🚗 Classic Fault — Mercedes-Benz (1976–1985)
W123 OM617 diesel injection pump timing drift
💰 Estimated Repair Cost
$50 – $180 USD
Parts and labour estimate
🔧 Tools Required
Dial gauge, timing degree disc, injection pump tools
📋 Overview
Injection pump timing drifts from correct setting as the pump coupling wears, causing hard starting, increased smoke, and reduced performance.
🩺 Symptoms
Black smoke under load. Hard cold starting. Reduced fuel economy. Engine knock at idle.
🔍 Possible Causes
Worn pump drive coupling. Incorrect initial timing setting. Wear in pump body.
🛠️ Diagnosis Steps
Check pump timing with dial gauge on front of pump. Standard timing is 24 degrees BTDC for most OM617 engines.
✅ Most Confirmed Fix
Adjust pump timing to specification. Replace worn drive coupling.
72% of users confirm this fix worked (22 reports)
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