Vapour-Like Smoke From the Exhaust

[eagle0001]

The car is emitting smoke, as you can see, but not immediately when I start it – it appears after a few minutes. When I drive and pick up speed, the smoke disappears, but it comes back when I stop at a traffic light or when I’m parking.

The smoke has no smell, and it looks more like vapour than actual smoke. The temperature was 3°C when I recorded the video, but even after driving long distances (up to 200 km), the smoke doesn’t go away.

I took it to the dealership, and they told me there’s nothing wrong. The smoke wasn’t appearing in the same way when they checked, but it still doesn’t look normal.

Does anyone have any idea what could be causing this?

 

[alabbasi]

Probably condensation. Exhaust is hot temps are cold so you'll get condensation. Like opening a cold canned drink on a hot day.

 

[jotter22]

Boil your kettle on the back doorstep! And welcome to the club.

Thanks Tony.

 

[ChrisPDuck]

As already suggested, this is most likely just water vapour (invisible) condensing into visible steam as it hits the cold air. I was chatting to a friend about this the other day, during a journey in my car. He made the point that the amount of water produced by a running engine is probably proportional to the amount of CO2 it emits. This seems to make sense because both are the products of petrol combustion, in a fixed ratio. My E500 emits 260g of CO2 per km, so makes quite a lot of water vapour. I don't use my S600 in the winter, but at 340g/km I imagine I'd be driving around in a cloud

I'm guessing that the amount of condensation you see relates to how quickly it forms in the air. In a fully warmed engine/exhaust, most of the water leaves the exhaust as invisible water vapour - if the air is cold it condenses very quickly, and in the summer it disperses further before condensing so is less visible. Hence, even after a long drive you'll still see condensation if the air is cold.

If the exhaust is cold, a lot of the water vapour condenses into water on the inside of the exhaust. I remember being quite shocked when, after an early start, pootling along on local roads on a cold morning, I floored it away from the last junction before a dual carriageway and was treated to a cloud of steam billowing from the exhaust. I've now just put that down to the sudden increase in engine speed being enough to expel and heat the accumulated water.

 

[ChrisPDuck]

...and in the summer it disperses further before condensing so is less visible.

And of course, warm air can hold more water vapour, so in the summer it may not condense at all.

 

[eagle0001]

Thank you Chris and everyone. That does make sense

 

[ALFAitalia]

When mine was doing that it was because the coolant was leaking into the exhaust from the EGR valve....an easy and cheap fix. But your coolant level would slowly drop if this was the case. Surprised it's still steaming after a long journey if it's just condensation. Even on the coldest days the steam goes after a couple of miles on both mine...one petrol, one diesel.

 

[eagle0001]

I just did its service a month ago in the dealership and one mentioned a problem plus engine check light is not on, and I am also checking the coolant level every week and it is the same!

When mine was doing that it was because the coolant was leaking into the exhaust from the EGR valve....an easy and cheap fix. But your coolant level would slowly drop if this was the case. Surprised it's still steaming after a long journey if it's just condensation. Even on the coldest days the steam goes after a couple of miles on both mine...one petrol, one diesel.

 

[eagle0001]

When mine was doing that it was because the coolant was leaking into the exhaust from the EGR valve....an easy and cheap fix. But your coolant level would slowly drop if this was the case. Surprised it's still steaming after a long journey if it's just condensation. Even on the coldest days the steam goes after a couple of miles on both mine...one petrol, one diesel.

Was it also doing the same thing when it is warmer? Because today is a bit sunny and I noticed that it is way less than when it is cold

 

[ALFAitalia]

Only happened in the winter.... so never used it in the summer with the fault.