Common BMW N47 & B7 Engine Problems

by | Aug 24, 2021 | BMW, BMW News | 0 comments

BMW makes special cars, you know that like no one else! However, both the diesel engine (engine code N47) has one part that can, unfortunately, cause problems: the timing chain. This can stretch (with grinding, scraping noises in the engine), skip or tear (with serious engine damage as a result). The successor to these engines, the B47 (from 2014/2015 the successor to the N47, suffers from this evil.

Which engine code do I have?

To find out, here are the BMW types in which the N47 diesel engine was installed:

  • E model series: 1 series (E81, E82, E87, E88), 3 series (E90, E91, E92, E93), 5 series (E60, E61), X3 E83 2.0d
  • F model series: 1 series (F20, F21), 3 series (F30, F31), 5 series (F10, F11, F07), X3 F25
  • Engine power: 115, 143, 163, 177, 184, 204 and 218 hp
  • Models: sedan, touring, convertible, coupe and SUVs X1 and X3
  • Transmission: manual and automatic

The new B47 diesel engine is used in the following BMW types:

  • F model series: 1-series (F20, F40, F48), 2-series (F22 / 23, F39, F45) 3-series (F25, F30 / F31 / F34,), 4-series (F26, F32 / F33 / F36, F44), 5-series (F15)
  • G Model series: 3-series (G01, G20), 4-series (G02), 5-series (G30 / G31), 6-series (G32)
  • Engine output: 116, 150, 170, 190, 205, 224 and 232 hp
  • Models: Sedan, Gran Turismo, Gran Tourer, Cabrio, Gran Coupé and SUVs X1, X2, X3, X4, X5, sDrive, xDrive
  • Transmission: manual and automatic

The most common problems with the BMW N47 / B47 engine:

    • Stretched timing chain
    • Cracked or broken timing chain

Timing chain problems on BMW diesel engines N47 and B47

Are you the proud owner or driver of a BMW diesel with engine code N47 or the newer B47? With these diesel engines, BMW developed a powerful, economical engine that is somewhat fragile … These engines are known for being confronted with high repair costs after around 50,000 km, as there are problems with the timing chain .

How the timing chain works

In the engine, air and fuel are compressed in the cylinder by the piston. The combustion of this mixture of air and fuel causes the pistons to move downwards. The exhaust gases from the combustion are then removed from the cylinder. This whole process is technically highly complex and requires very precise control. The timing chain takes on the task of connecting the camshaft to the crankshaft. With perfect coordination, the crankshaft must rotate twice in the time in which the camshaft rotates once. Depending on the position of the piston, the valves are then opened and closed.

Timing chain set BMW diesel N47 and B47

Stretched timing chain in the BMW N47 or B47 engine

Noises from the engine compartment can be used to identify a timing chain that is stretching. First you hear a very small grinding noise in the motor, then the grinding becomes louder. At around 1,500 rpm you can even hear it inside the car. If you continue to drive without taking any action, you do so at your own risk! At the latest when the warning light for the engine management lights up, you can no longer ignore the problem: This can result in very costly engine damage. If the timing chain skips over a tooth of the gearwheel or even breaks it off completely, the precise process in the piston is disturbed and the valves no longer open at the right moment. They may then touch the piston or damage it. The connecting rod and the valves themselves can also be bent.

The cause of the timing chain stretching

There are no reliable findings on this. It looks like a design error is likely. However, it is not possible to determine exactly whether it was a material defect that made the chain too long, or whether the gears have the wrong diameter, or the guide rails, or whether the chain swings back and forth too much. But it is also quite possible that the oil change intervals play a role … It is of the utmost importance that the oil is regularly replaced with high-quality new oil, with the specified type of oil.

Timing chains that skip or break

A timing chain that stretches too far over time can cause a tooth on the sprocket to be skipped. This in turn means that the valves no longer open at the right time. When that happens, it is immediately noticeable because the engine no longer runs smoothly. The worst-case scenario with this problem would be that the valves touch the piston. That could lead to crooked valves, broken pistons or even demolished connecting rods! The timing chain itself could even tear. All of this would cause considerable damage!

Causes of stretched or broken chains

One can only speculate about the exact causes. A design flaw seems obvious, but whether it is a material flaw (making the chain too long and skipping), the diameter of the gears, the guide rails, or excessive chain slack cannot be said with certainty. However, the oil change interval can also play a role … Regular oil changes with high-quality (prescribed) oil are extremely important for both the BMW N47 engine and the B47!

Solution for cracked or broken timing chains

Reputable BMW repair centers have a lot of experience in carrying out these repairs and can therefore offer them at a very affordable price. And they understand the problem in and out! That is why most these companies give a guarantee of up to one year * on this repair !

Typical process of repairing cracked or broken timing chains:

  • Replacement of the timing chain, the oil pump chain and the guide rails including the gears, tensioners and all the seals that go with them
  • Replacement of damaged valves, the valve cover and head gasket
  • Replacement of the engine oil including the oil filter
  • Coolant replacement
  • Delete the error memory and read all components again
  • Of course, they only use original BMW spare parts.

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