🚗 Classic Fault — Mercedes-Benz W115 (1968–1976)
M115 oil consumption — valve stem seals worn
💰 Estimated Repair Cost
$80 – $250 USD
Parts and labour estimate
🔧 Tools Required
Valve spring compressor, air line
📋 Overview
Worn valve stem seals allow oil to be drawn past the valve stems into the combustion chamber. This causes blue smoke on cold startup that clears as the engine warms.
🩺 Symptoms
- Blue-grey smoke on cold start clearing after warmup
- gradual oil consumption
- blue smoke on deceleration
🔍 Possible Causes
- Worn or hardened valve stem seals
- worn valve guides
🛠️ Diagnosis Steps
Perform compression test. Check which cylinders have oily plugs. Add oil to cylinders with low compression.
✅ Most Confirmed Fix
Replace valve stem seals. Replace all seals simultaneously.
74% of users confirm this fix worked (19 reports)
🏷️ Parts Needed
M115 valve stem seal set
🔗 Other Mercedes-Benz W115 Faults
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