BMW N43

The BMW N43 is a straight-4 DOHC piston engine which replaced the N42 and was sold from 2007-2011.

Compared with its N42 predecessor, the N43 features direct injection. The N43 was sold alongside the N45 engine (which does not have valvetronic or direct injection)^[1] and the N46 (which does not have direct injection) straight-4 engines.

Models

N43B16

The N43B16 has a 1599 cc displacement and produces 90 kW (122 PS; 121 hp) and 160 Nm.^[2]

Applications:

• 2007-2011 E87 116i
• 2008 E90 316i

BMW N43B16 engine reliability, problems and repair

BMW N43B16 engines were produced to replace N42B18. However they showed up a bit late and were constructed on base of N43B20. This motor had cylinders with smaller diameter which was 82 mm in comparison with 2-liter N43B16 engine. It has shorter crankshaft which is 75.7 mm stroke. Displacement was decreased to 1.6 liters. If compared with its predecessor N42B18 new engine has pistons with higher compression ratio (12). At the same time direct injection system was installed while Valvetronic was removed. Siemens MSD 81.2 engine control unit is used in new motor. This engine was produced for BMW 16i models. N45B16 and N46B18 versions were also produced along with new engine for cheaper BMW modifications. 1.6-liter turbocharged 4-cylinder N13B16 engine turned out to be a new gen motor which replaced N43 in 2011. ===

BMW N43B16 disadvantages and problems

This engine is a smaller version of N43B20 and has the same problems. More detailed information on possible BMW N43 malfunctions is provided below:

1. Engine vibration. This problem is one of the most common in N43. You need to change injectors.

2. Misfire and rough idling on N43. The problem is mainly connected with ignition coils. You should check them and replace in case of necessity. 3. Vacuum pump starts leaking after 40,000-50,000 miles (60,000-80,000 km) of mileage. The only way to solve this problem is to change pump. Don’t forget to check conditions of your cooling system in order to prevent it from overheating.

4. N43 is rather demanding when it comes to motor oil and its quality. Operating temperature of the engine is rather high. It means that low quality oil may lead negative consequences for the engine. That is why you need to use motor oil that is recommended by BMW brand.

If you take care of N43B20 engine and proceed with all necessary changed and maintenance, it will serve you for a long time with minimum problems.

BMW Petrol N43 Engine failures - How To Prevent BMW Petrol Engine N43 Failures

What is causing the failures? This is not down to a design problem, or a mechanical problem with the engine as such but more down to "long-life" servicing which can lead to oil changes occurring every 20,000 miles. Combine this type of servicing with cars which have missed a service, gone overdue on a service, or even gone to a non-specialist garage where an incorrect oil grade is used during the service, and the result can be catastrophic. The problem is the engine oil. Engine oil is not only designed to lubricate moving parts it is also used to control temperatures inside the engine, for example by cooling pistons, but also to absorb carbon. Carbon is by-product of combustion and occurs both in petrol and diesel engines. As soon as you put new oil into an engine it is absorbing carbon from the moment you start the engine, when the oil is new this is not a problem the carbon is absorbed effectively and the car operates as normal. When the engine oil is "used" and has maybe done 10,000 miles + it becomes less effective, when the oil has done 15,000 + miles the oil can no longer absorb the carbon as it should and it starts to solidify or "sludge up" / "coke up" .This sludge then sticks to important engine components and can begin to block oil galleries and oil pumps. Once oil pumps, and galleries begin to block up, key components begin to get starved of oil, this can quickely lead to permanent damage and failure, often resulting in expensive repairs.

N43B20

The N43B20 has a 1995 cc displacement and produces up to 125 kW (170 PS; 168 hp) and 210 Nm.^[2]

Applications:

105 kW and 190 N·m (140 lb·ft) version

• 2008-2011 E87 118i

125 kW and 210 N·m (155 lb·ft) version

• 2007-2011 E87 120i
• 2007-2011 BMW E90 318i (143 hp) form
• 2007-2011 E90 320i
• 2007-2011 E91 320i
• 2007-2011 E92 320i
• 2007-2009 E60 520i

See also

• List of BMW engines

N43 also see in 318i in 105ps 143 hp form

References

External links

• The UnixNerd's BMW N43 engine page with photos, history and common problems.