The 1.0-liter 3-cylinder Mitsubishi 3B21 engine was assembled in Japan from 2006 to 2014 and installed on the second generation of the W451 Smart Fortwo model, popular in Europe. Such a power unit according to the nomenclature of the Daimler-Chrysler concern is known as the Mercedes M132.
3B2 family: 3B20, 3B20T, 3B21, 3B21T.
Specifications
| Production years | 2006-2014 |
| Displacement, cc | 999 |
| Fuel system | distributed injection |
| Power output, hp | 61 – 71 |
| Torque output, Nm | 89 – 92 |
| Cylinder block | aluminum R3 |
| Block head | aluminum 12v |
| Cylinder bore, mm | 72 |
| Piston stroke, mm | 81.8 |
| Compression ratio | 11.4 |
| Features | DOHC |
| Hydraulic lifters | no |
| Timing drive | chain |
| Phase regulator | MIVEC |
| Turbocharging | no |
| Recommended engine oil | 5W-30 |
| Engine oil capacity, liter | 3.3 |
| Fuel type | petrol |
| Euro standards | EURO 4/5 |
| Fuel consumption, L/100 km (for Smart Fortwo 2008) — city — highway — combined |
6.1 4.0 4.7 |
| Engine lifespan, km | ~200 000 |
| Weight, kg | 67 (without attachments) |
The engine was installed on:
- Smart Fortwo 2 (W451) in 2006 – 2014.
Disadvantages of the Mitsubishi 3B21 engine
- The engine exists in two versions and a simple modification does not cause trouble;
- In the MHD hybrid, the starter-alternator belt warps and wears out quickly;
- A broken belt causes the pump to stop and the head immediately leads due to overheating;
- By 100,000 km, the rubber rings on the candle wells are tanned and oil gets there;
- There are no hydraulic lifters and valve clearances need to be adjusted every 100,000 km.
Frequently asked questions about the Mitsubishi 3B21
How much power does the Mitsubishi 3B21 make?
The Mitsubishi 3B21 develops 61 - 71 hp and 89 - 92 Nm of torque.
How much oil does the Mitsubishi 3B21 take and which one?
Engine oil capacity: 3.3 liters. Recommended oil: 5W-30.
Does the Mitsubishi 3B21 have a timing belt or chain?
The Mitsubishi 3B21 uses a timing chain.
Is the Mitsubishi 3B21 turbocharged?
No, the Mitsubishi 3B21 is naturally aspirated.
Does the Mitsubishi 3B21 need valve clearance adjustment?
Yes, there are no hydraulic lifters, so the valve clearances have to be checked and adjusted periodically.
How long does the Mitsubishi 3B21 last?
The typical lifespan of the Mitsubishi 3B21 is ~200 000 km with proper maintenance.
What is the fuel consumption of the Mitsubishi 3B21?
Smart Fortwo 2008: city 6.1, highway 4.0, combined 4.7 L/100 km.
What cars was the Mitsubishi 3B21 installed on?
Smart Fortwo 2 (W451) in 2006 - 2014.
What are the common problems of the Mitsubishi 3B21?
The engine exists in two versions and a simple modification does not cause trouble. In the MHD hybrid, the starter-alternator belt warps and wears out quickly. All known problems.
