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.

 

[ChrisPDuck]

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.

This is the first winter that I've owned this E500. When I first noticed what I thought was excessive condensation (compared to my previous Chrysler diesel) my first thought was coolant, but the level hasn't moved since I've been monitoring it. I'm now convinced it's purely the water that's the by-product of petrol combustion. I'm not saying I'm right, but if I am then shouldn't there always be some on the coldest of days, regardless of how far the car's been driven? Cold air + hot exhaust gases containing invisible water vapour = condensation. What happens to the water vapour if it doesn't condense out? Maybe the quantity of water vapour stays below what can be absorbed by the air for many/most engines?

 

[ALFAitalia]

Maybe.....hopefully you are correct......last think you want is a big bill!!

 

[E55BOF]

When you went out this morning, was it cold? Could you see your breath condensing? Unless there are other signs of a problem, your car's exhaust is doing the same. Don't worry about it.

 

[ALFAitalia]

Just concerns me that its still doing it after a long journey.....mine don't do that.

 

[eagle0001]

Here is another picture of it this morning. It was 2 degrees and the car was warm enough. What concerns me is that I am looking at other cars and mine is producing more smoke than all of them plus it is coming from one exhaust not both

 

[ALFAitalia]

Quite....
Which engine?.....lots of them only have one exhaust.....the other one is often fake.....look underneath.

 

[eagle0001]

Quite....
Which engine?.....lots of them only have one exhaust.....the other one is often fake.....look underneath.

It's C-class 2 litre patrol with two exhausts and the second one is not fake.

You can see from this angel the second exhaust produce a lot less smoke than the other one

 

[DSM10000]

It's C-class 2 litre patrol with two exhausts and the second one is not fake.

You can see from this angel the second exhaust produce a lot less smoke than the other one

As said, it's condensate, not smoke. As long as you are not loosing coolant don't worry.

 

[Petrol Pete]

The 'smoke' still there after a 120 mile drive ??

Something is not right .

My 150K+ mile M113 AMG V8 emits steam/condensate on a cold start up and its gone within minutes.

 

[DSM10000]

The 'smoke' still there after a 120 mile drive ??

Something is not right .

My 150K+ mile M113 AMG V8 emits steam/condensate on a cold start up and its gone within minutes.

But the exhaust gases are still comprised of a lot of water vapour which will still condense if the air is cold enough?