Smoke and water in the tailpipe of 2004 Kia Cerato

It’s important to differentiate smoke from water vapour when it comes to problems like this that may not be a problem at all. Given you’re also seeing water being emitted from the tailpipe, I’m tipping that this is all happening when you first start the car in the morning.

The fact is, this is perfectly normal behaviour from a conventional engine and is simply the engine doing what it does. The water and water vapour is visible on these colder mornings we’re experiencing right now in Victoria because the exhaust isn’t yet hot enough to turn it to steam (steam is actually invisible, water vapour is the white mist you can see). As the car warms up and the exhaust gets hotter, it will turn the water into steam and you won’t notice it.

But how does the water and vapour get into the exhaust in the first place? Believe it or not, water is a natural by-product of burning petrol in an engine. And until the engine and exhaust are hot enough to turn that water to steam, it’s visible to the naked eye. Which is when a lot of people start to get worried. But they needn’t, as it’s nothing to be concerned about.

The flip-side is if the tailpipe is actually emitting white or blue-ish smoke, at which point you potentially have a worn or damaged engine. This will happen regardless of whether the engine is hot or cold and it won’t go away once the engine is warmed up. If that’s the case, you need to have the engine compression tested by a mechanic as the first step towards finding the cause.