Engine BMW N46B20

BMW N46 gasoline engines were produced from 2004 to 2015 and were installed on almost all compact and medium-sized models of the group of that time. The 2.0-liter N46B20 engine was created on the basis of the N42B20 and at first glance does not differ from its predecessor, but it is not.

The differences between the BMW N42 and the N46 are as follows: a different crankshaft, balancer shafts, connecting rods and 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 some other little things. Otherwise, this is the same N42 with its pluses and minuses. Bosch ME 9.2/Bosch MV17.4.6 engine management system.

Since 2007, the engine has been slightly upgraded, the intake manifold and exhaust camshaft have been replaced, the new modification was called the N46N.

This motor was used on BMW cars with an index of 18i and 20i.


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
Engine lifespan, km ~300 000

Disadvantages of the N46B20 engine

  1. Excessive consumption of engine oil. As with the N42 series, the main reason is the destruction of the valve stem seals due to prolonged filling of low-quality oil. The oil scraper rings also suffer from this. Both components need to be replaced after 50 thousand kilometers. Bad oil can easily damage the Vanos and Valvetronic systems, crankcase ventilation valve and the oil pump.
  2. Motor jitter. The system for changing the valve timing is clogged – Vanos. Cleaning required.
  3. The appearance of noise and diesel effect. The same reasons as on the N42 version are a loosening of the timing chain or a breakdown of its tensioner. Such ailments appear already after passing 100 thousand kilometers.

Fifty thousand kilometers of run can be marked by leaking valve cover gaskets and vacuum pump. To avoid most of the engine malfunctions and to make it work harmoniously, like a good clockwork, you can, if you constantly monitor its condition, undergo maintenance on time and fill it with only good oils and fuel.

3 thoughts on “Engine BMW N46B20”

  1. your lifspan km definitely wrong!
    This engine would never make 300 000! i had multiple times and it start troubling with 100000.
    Please correct this misinformation or hide such unserious information

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