From 2004 to 2015, nearly all of the group’s compact and medium-sized models had BMW N46 gasoline engines. Although it appears to be identical to its predecessor, the 2.0-liter N46B20 engine was developed based on the N42B20.
The BMW N42 and N46 are distinguished by a different crankshaft, balancer shafts, connecting rods, a cylinder head cover, a redesigned intake manifold, a modified timing chain tensioner, new spark plugs and a generator, a Valvetronic control unit integrated into the ECU, and a few other small details. Other than that, this is the same N42, with all of its benefits and drawbacks. Bosch ME 9.2 and Bosch MV17.4.6 engine management systems.
Since 2007, the engine has undergone a minor upgrade with the replacement of the exhaust camshaft and intake manifold; this new modification is known as the N46N.
BMW vehicles with indexes of 18i and 20i were equipped with this motor.
Specifications
| Production years | 2004-2012 BMW Plant Hams Hall |
| Displacement, cc | 1995 |
| Fuel system | injector |
| Power output, hp | 129 – 150 143 – 170 (N46N) |
| Torque output, Nm | 180 – 200 190 – 210 (N46N) |
| Cylinder block | aluminum R4 |
| Block head | aluminum 16v |
| Cylinder bore, mm | 84 |
| Piston stroke, mm | 90 |
| Compression ratio | 10.5 |
| Features | Valvetronic |
| Hydraulic lifters | yes |
| Timing drive | chain |
| Phase regulator | double VANOS |
| Turbocharging | no |
| Recommended engine oil | 5W-30 |
| Engine oil capacity, liter | 4.25 |
| Fuel type | petrol |
| Euro standards | EURO 4/5 |
| Fuel consumption, L/100 km (for 320i E90) — city — highway — combined |
10.7 5.6 7.4 |
| Engine lifespan, km | ~300 000 |
Disadvantages of the N46B20 engine
Excessive engine oil consumption. Similar to the N42 series, the primary cause is the long-term filling of inferior oil, which destroys the valve stem seals. This is also a problem for the oil scraper rings. After fifty thousand kilometers, both parts must be changed. The oil pump, crankcase ventilation valve, and Vanos and Valvetronic systems can all be readily harmed by bad oil.
Jittery motor. Vanos, the system that modifies the timing of the valves, is clogged. It must be cleaned.
The diesel effect and the appearance of noise. The timing chain loosening or the tensioner breaking down are the same causes as for the N42 version. Even after traveling 100,000 kilometers, such illnesses start to manifest.
Leaking valve cover gaskets and vacuum pumps are indicators of 50,000 kilometers of run. If you keep a close eye on the engine’s condition, schedule regular maintenance, and only use high-quality fuel and oils, you can prevent the majority of engine problems and make it operate smoothly, much like a well-functioning clockwork.