OM 660 is a 3-cylinder in-line engine. Engine power is 45 hp (33 kW) with an engine displacement of 799 cc (0.8 liters). The OM660 engine is equipped with a single overhead camshaft, two valves per cylinder, and an aluminum alloy cylinder block and head. It is turbocharged and has an outlet gas recirculation system.
The Mercedes OM660 was updated in 2007 with improved performance thanks to a new Common Rail fuel system with increased boost pressure, and again in 2011 with further improvements in performance and efficiency.
Mercedes diesel R3 family: OM660, OM639.
Specifications
| Production years | 1999-2014 |
| Displacement, cc | 799 |
| Fuel system | Common Rail |
| Power output, hp | 41 – 54 |
| Torque output, Nm | 100 |
| Cylinder block | aluminum R3 |
| Block head | aluminum 6v |
| Cylinder bore, mm | 65.5 |
| Piston stroke, mm | 79 |
| Compression ratio | 18.0 |
| Hydraulic lifters | yes |
| Timing drive | chain |
| Turbocharging | BorgWarner KP31 |
| Recommended engine oil | 5W-30 |
| Engine oil capacity, liter | 2.7 |
| Fuel type | diesel |
| Euro standards | EURO 4/5 |
| Fuel consumption, L/100 km (for Smart Fortwo 2005) — city — highway — combined |
3.9 3.1 3.4 |
| Engine lifespan, km | ~250 000 |
| Weight, kg | 86 |
The engine was installed on:
- Smart Fortwo 1 (W450) in 1999 – 2006, Fortwo 2 (W451) in 2006 – 2014.
Disadvantages of the OM660 engine
- Before 250-300 thousand km the turbocharger and the timing chains often have to be replaced;
- The EGR valve gets dirty quickly, which noticeably reduces power;
- The plugs in the cylinder head often rust, which leads to coolant leaks;
- Euro 5 versions have a particulate filter that can cause trouble.
Frequently asked questions about the Mercedes OM660
How much power does the Mercedes OM660 make?
The Mercedes OM660 develops 41 - 54 hp and 100 Nm of torque.
How much oil does the Mercedes OM660 take and which one?
Engine oil capacity: 2.7 liters. Recommended oil: 5W-30.
Does the Mercedes OM660 have a timing belt or chain?
The Mercedes OM660 uses a timing chain.
Is the Mercedes OM660 turbocharged?
Yes, the Mercedes OM660 is turbocharged (BorgWarner KP31).
Does the Mercedes OM660 need valve clearance adjustment?
No, the Mercedes OM660 has hydraulic lifters, so the valve clearances do not need to be adjusted.
How long does the Mercedes OM660 last?
The typical lifespan of the Mercedes OM660 is ~250 000 km with proper maintenance.
What is the fuel consumption of the Mercedes OM660?
Smart Fortwo 2005: city 3.9, highway 3.1, combined 3.4 L/100 km.
What cars was the Mercedes OM660 installed on?
Smart Fortwo 1 (W450) in 1999 - 2006, Fortwo 2 (W451) in 2006 - 2014.
What are the common problems of the Mercedes OM660?
Before 250-300 thousand km the turbocharger and the timing chains often have to be replaced. The EGR valve gets dirty quickly, which noticeably reduces power. All known problems.
What engines are related to the Mercedes OM660?
Mercedes diesel R3 family: OM639.
