Air purge and high oil consumption in N53 engine in BMW – how to fix it?

BMW driver question

I have owned a BMW 5 Series F10 with the N53B30 engine (205 hp) for less than three months. I bought the car from the first owner with a mileage of 53,000 km with a defect in the fuel injectors identified by the service department.

All injectors were replaced by me with new ones (index 11) and adapted. The engine runs without complaint. No errors. However, I have a problem with too high oil consumption, that is approx. 1 liter for about 1000 – 1200 km.

Where to look for the cause? The engine starts without a problem. It works evenly, although on cold it sometimes happens that, for example, when stopping at traffic lights, the revs slightly wavy, it lasts a second, and then everything returns to normal, on warm I did not notice this. It does not smoke either on cold at startup or while driving. Power develops smoothly, no vibrations, oscillations, etc. ISTA does not show any errors.

What I have noticed, however, is that when extinguishing the engine, there is a distinctive hissing sound from somewhere in the vicinity of the air intake/valve cover, as if some expansion valve is bleeding air. Is this normal in this type of engine? Could it be the air pressure relief? It is not some particularly loud sound, but clearly audible.

I should add that I have more BMW cars, but I have not encountered the problem described above in any of them.

Response from BM Cars service

The N53 engine is subject to the disadvantage of high oil consumption. The norm stated in the service documentation is 1 liter per 2 – 3 thousand kilometers.

An additional problem is poor quality injectors, which often cause oil to be flushed out of the cylinder wall and cylinder compression to be lost or compromised. If your engine is consuming oil at the level of 1 liter per thousand kilometers, all oil leaks should be checked and eliminated first. The most common are from the valve cover gaskets and the oil pan.

The second step is to check the intake manifold for oil appearing in it. If this is the case, then replace the oil separators:

• on the valve covers,
• the rear cover with the diaphragm from the intake manifold
• oil separator located behind the timing drive.

By the way, it is possible to check the condition of the valve train. In engines after considerable mileage (about 200,000 kilometers), it is common for the timing chain to be crushed and stretched. The final step in a possible repair is to assess the condition of the cylinder liners and piston rings (compression measurement with oil test).

The oil you used, Castrol 5W30, is the approved oil for this engine model. A slightly better variation of this oil is Castrol 0W40 – resistant to higher temperatures. Changing to semi-synthetic or mineral oil is not allowed and will not reduce wear.

The described wheezing noises when shutting down the engine may indicate worn refusals on the valve covers.

The best way to check the condition of all components will be a visit to our service center.

Other BMW tips related to the topic at hand

• Error of short circuit to ground and shortage of boost in BMW – how to fix?
• Engine does not start – faulty fuel pump?
• Jerking and white smoke on cold engine in BMW 3

Read more tips and ask your own question