🚗 Classic Fault — Mercedes-Benz W115 (1968–1976)
M115 head gasket failure — coolant-oil mixing
💰 Estimated Repair Cost
$200 – $800 USD
Parts and labour estimate
🔧 Tools Required
Block tester, pressure tester, torque wrench
📋 Overview
Internal head gasket failure allows coolant to enter the oil system. Mayonnaise-like emulsion on the dipstick or inside the oil filler cap is the classic indicator. The engine must not be run in this condition.
🩺 Symptoms
- Mayonnaise emulsion on dipstick or oil filler cap
- coolant level dropping
- overheating
- white smoke from exhaust
🔍 Possible Causes
- Internal head gasket failure between water jacket and oil gallery
- cracked cylinder head
🛠️ Diagnosis Steps
Check oil dipstick — milky or frothy oil confirms coolant mixing. Check oil filler cap interior.
✅ Most Confirmed Fix
Replace head gasket. Machine head face. Use new head bolts. Follow correct torque sequence.
65% of users confirm this fix worked (11 reports)
🔗 Other Mercedes-Benz W115 Faults
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