Fluid sound and smoke from BMW X3

Hello, I'm Marianne and I've owned a 2007 BMW X3 E83 3.0si for a while now. The car has a gasoline engine and has 300,909 km on the odometer. It drives fine, but sometimes it hesitates and there's a whistling sound, accompanied by a lot of smoke. I think it's unburnt fuel. If you turn the car off and on again, the problem is temporarily solved. We'd like to solve this permanently, but we don't know how. Are there people who recognize this problem or know what the cause might be?

(Translated from Dutch)

5 comment(s)

The symptoms you're describing could be related to a vacuum leak, which can cause hesitation, whistling sounds, and unburnt fuel issues. Start by inspecting all vacuum hoses for cracks or disconnections, especially around the intake manifold and throttle body. A smoke test can also help identify any hidden leaks. Let me know if you find anything or if you have further questions!

Quotation:
@CarlyMechanic wrote on
The symptoms you're describing could be related to a vacuum leak, which can cause hesitation, whistling sounds, and unburnt fuel issues. Start by inspecting all vacuum hoses for cracks or disconnections, especially around the intake manifold and throttle body. A smoke test can also help identify any hidden leaks. Let me know if you find anything or if you have further questions!

Thank you for your response. All the hoses have been replaced, new valve cover gasket, new crankcase ventilation, new spark plugs. It was read again at the garage today, now it indicates a vanos exhaust system issue.

(Translated from Dutch)

Quotation:
@Mariannebmwe83 wrote on
Thank you for your response. All the hoses have been replaced, new valve cover gasket, new crankcase ventilation, new spark plugs. It was read again at the garage today, now it indicates a vanos exhaust system issue.

The VANOS system can indeed cause performance issues if it's malfunctioning. Start by checking the VANOS solenoids for any signs of clogging or failure, as they can affect timing and lead to hesitation and smoke. Cleaning or replacing the solenoids might resolve the issue. Please update me on your progress or if you have any further questions!

Quotation:
@CarlyMechanic wrote on
The VANOS system can indeed cause performance issues if it's malfunctioning. Start by checking the VANOS solenoids for any signs of clogging or failure, as they can affect timing and lead to hesitation and smoke. Cleaning or replacing the solenoids might resolve the issue. Please update me on your progress or if you have any further questions!

Thank you for your response. The problem does not always occur. After a few starts (short distances) it sometimes goes wrong over longer distances (not always).

(Translated from Dutch)

Quotation:
@Mariannebmwe83 wrote on
Thank you for your response. The problem does not always occur. After a few starts (short distances) it sometimes goes wrong over longer distances (not always).

Intermittent issues can be tricky. Since the problem is related to the VANOS system, consider checking the oil condition and level, as dirty or low oil can affect VANOS operation. Ensure you're using the correct oil type for your BMW. If the issue persists, it might be worth having a professional mechanic inspect the VANOS system more thoroughly. Let me know how it goes or if you have more questions!

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