N57 - Powerful diesel engine with weak points

The N57 engine has been used since 2008 in various versions in several BMW models such as the BMW E90 and the BMW F10. This engine is available in different variants and is characterized by its overall reliability, but it also has some weaknesses. After more 10 years After intensive engagement with this engine, we now know what is important for this unit.

1.) Low oil pressure in the lower RPM range and idle can lead to significant damage to the N57. The insidious thing about the low oil pressure is that the vehicles do not display it, and the vehicle owner is not warned of an impending engine damage through warning messages. Therefore, during a repair, we always install a more powerful and durable upgrade oil pump that can deliver more pressure than the factory pump. This greatly increases the reliability and lifetime of the N57 engine.

2.) Timing chain problems The N57 often affects not only the chain itself but also the guide rails and the chain tensioner. Defects lead to wear and chipping in the oil pan and damage the oil pump and thus the entire engine. Signs of a defective timing chain are rattling and clattering noises when starting the engine.

3.) An EGR cooler (Exhaust Gas Recirculation) Lowers the operating temperature of the N57 engine and reduces the emission of nitrogen oxides. Unfortunately, the recirculation of exhaust gases promotes the formation of soot in the components that are flowed through, such as the intake manifold, EGR valve, and EGR cooler, leading to rough idling, increased fuel consumption, and smoke development.

4.) Main and connecting rod bearing damage They are among the most well-known and also most serious weaknesses of the N57 engine. These manifest as strong knocking noises and can, in severe cases, lead to total engine failure if the main bearing rotates with the engine block and damages it.

One of the most common causes of a major engine failure in the N57 is a Storage damage in the area of the main bearings or the connecting rod bearing within a mileage of 150,000 to 200,000 kilometers. Almost always, the damage is preceded by a longer mileage with insufficient oil pressure. The oil pump of the N57 engine is simply undersized.

Problematic about this damage is that not only the main bearings and the crankshaft of the N57 are affected, but also the engine block is severely damaged as a result of the main bearing damage and is written off as a total loss by many businesses.

The online market is flooded with spare parts for the N57 engine. However, caution is advised if you are considering buying a used engine block or a new crankshaft as a supposed bargain. 

If a storage damage has occurred, the effects on the crankcase are not always immediately apparent. Even if the main bearing shells of the N57 engine did not rotate, the knocking of the crankshaft in the housing causes significant damage. This only becomes visible when we check the bearing block seating surface in the crankcase with a feeler gauge.

It is clearly visible that the bore of the main bearing appears undamaged, but the bearing surface of the main bearing block has sagged by several tenths of a millimeter, making the runout of the crankshaft in the engine block impossible. Used engine blocks are priced between €1000-2000 online. The cost for repairing the main bearing journal is in the economically acceptable range of €1300-1800, which is why vehicle owners should definitely prefer it to replacement.

When purchasing a crankshaft We always ensure that this is an original part from BMW. There are already numerous manufacturers selling crankshafts at supposedly low prices on the internet. The quality of these crankshafts has been questioned multiple times. Dimensional accuracy, runout, and also the hardness depth of the bearing journals deviate significantly from the original and are therefore not recommended.