How to fix BMW Blow white smoke from exhaust?

In this post we will share a real case on fix BMW blow white smoke from exhaust. Following are details:

Vehicle information

Country Specifications: EUR

Car series: 740Li G12

Drive device: xDrive

Engine: B58 B30M0

Displacement: 3.0 T

Assemble country: DEU

Production date: 2016-03-01

Total mileage: 53706 km


Fault symptom:

After driving for a period of time, parking for about 20 minutes, a large amount of white smoke will be emitted from the exhaust pipe when restarted, and it will disappear after a while, and hot cars are prone to appear this fault.



Repair process

1. Drive test can reproduce the symptom reflected by customer.

2. There are the following possible causes for white smoke:

Burn antifreeze

Burn oil

Burn water

3. The mileage of this car is not high. It should be impossible to burn oil, and the customer has not encountered an oil level alarm. Then check the cooling system first.

4. Check that the liquid level of the antifreeze high temperature kettle is normal, and that of the low temperature kettle is lower than the maximum value.

The B58 engine's charge air cooling is water-cooled, and there may be water leakage from the intercooler or turbine.


5. The pressure test of the low-temperature cooling system for 30 minutes, the pressure has dropped, and the check liquid level is lower than that before the pressure. Suppress the high temperature cooling system without pressure drop.

6. According to the cooling system diagram, it is possible to exclude the water leakage from the turbine, which may be caused by the intercooler. Therefore, after removing the intercooler and inspecting it, there are indeed water stains. When the intercooler was put into the water to press the test, there was an obvious leak.


7. After replacing the intercooler, the customer drove for about a week, reflecting that the problem still exists! The vehicle was brought into the workshop for repair again. This time, the last replacement parts were re-inspected. The cooling system was normal and did not leak!

8. There is no water leakage, will it be burning oil?

Check for oil stains in the intake duct, oil stains on the intake valve, and oil stains on the spark plug.


After cleaning, the test drive came back with oil stains, Oil and grease on the intake valve.


9. with the above inspections: there are more oil stains on the air inlet and spark plug, and the cylinder is dry and free of oil stains.

It is suspected that the crankcase ventilation system caused more oil stains in the intake duct. Recently, the symptom of more B48 models burning oil is similar to this car.

10. Then removed the valve chamber cover assembly and check the crankcase ventilation system. No air leakage was found like the B48.


11. In order to rule out suspicions, replace a valve cover of the normal vehicle and tested for two days without white smoke. Check the spark plug, no oil stain.

12. Replace a new valve cover, no white smoke feedback after two months.


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