Leaking water from the BMW exhaust – what does it mean and how to prevent it?

BMW driver question

I have a question. Where are the very large amounts of water in the exhaust system coming from? In my car, it leaks from the muffler after every firing. What is the reason for such a defect?

The problem affected the BMW 320i F30, but it happens in other BMWs.

Response from BM Cars website

In gasoline engines, water vapor is part of the exhaust – a product of fuel combustion. On a cold engine and on an unheated exhaust system including a cold catalytic converter, water vapor condenses. It comes out of the exhaust pipe in tiny amounts.

When starting off, there may even be the phenomenon of a trickle of water leaking from the exhaust pipe. This is still condensed steam that has accumulated in the cold exhaust system. It is very important that vehicles with gasoline engines are operated in a way that allows them to reach operating temperature.

Frequent driving on very short distances especially on cold days can lead to the appearance, in addition to clouds of steam from the exhaust pipe and dripping water, also rust on the oil level dipstick and “butter” on the oil cap. This is due to condensation under the valve cover and in the engine crankcase.

If in doubt, we suggest starting with a full computer diagnosis to check the condition of the engine and exhaust system.

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