M104
Mercedes-Benz · M104 2.8/3.2 I6
1990–1997
"W124/R129/W140 inline-6. One of Mercedes' most reliable engines. Bulletproof bottom end. Wiring harness biodegrades (uses soy-based insulation). Head gasket solid. 400k+ km possible."
Mileage Risk Timeline
When problems typically appear — enter your mileage to see your risk zone
Known Issues 1
Wiring harness biodegradation
▸Random electrical faults, codes, misfires
Mercedes used soy-based insulation — wiring crumbles with age.
Καλωδίωση σαπίζει — €500-2,000 αντικατάσταση.
Related Guides
Other Mercedes-Benz Engines
Tuning Potential
Limited — NA tuning only
Frequently Asked Questions
Is the Mercedes-Benz M104 reliable?
The Mercedes-Benz M104 scores 85/100 with a verdict of BEST. It has 1 documented issues with total repair costs between €500 and €2,000.
What are the common problems with the M104?
The most common issues are:
- Wiring harness biodegradation — high, repair cost €500–€2,000, 100,000 km–200,000 km
How much does it cost to repair the M104?
Total potential repair costs for all 1 known issues range from €500 to €2,000. The most expensive issue is typically .
What years was the M104 produced?
The Mercedes-Benz M104 was produced from 1990 to 1997. It is a 3199cc I6 petrol na engine.
Scores are calculated from documented issues, repair costs, and failure patterns across thousands of owner reports and technical sources. Learn about our methodology. Always inspect before you buy.