Exhaust white smoke just after startup !!

[Eng_Ahmad1986]

hello to all 🙂 

mine is mk8 fiesta Ecoboost 100ps automatic, I had this white smoke just after startup as you can see in the video, it only happens when the car sits overnight, it doesn't happen even if the engine is switched off for 3 or 4 hours, it happens only if sat overnight ( probable 12 hours ) , this white smoke doesn't seem condensation to me, because it starts several seconds after you just switch the engine on, it lasts for several seconds and then its gone, after a while when the engine warms up a little bit then the normal condensation starts to show itself, and also it doesn't look like condensation, I know how condensation looks like, it smells bad also but I can't determine if its that sweet smell of coolant or its oil, looks more like oil since it smells like burning rubber or plastic somehow.

oil and coolant levels are fine, but they may be fine for now because the leak ( wherever it is ) is not so large yet.

current mileage is 35k kilometers

previous history : 1- engine's short block was changed at the mileage of 26k kilometers due to a piston ring failure of cylinder no. 1

                            2- valve cover changed about 1 month ago because it was leaking oil .

car is still under warranty , but for the dealer to diagnose the issue the car should stay overnight with them, and what makes it harder to diagnose is that no oil or coolant loss ( yet ) and no trouble codes are stored , no MIL or any lights are up, and no drivability issues, I'm trying to have any clue or if there are tests to be done by me to narrow things down.

need help from you guys 🙂 what could that be !!

Thank you for considering 🙂 

1.0 Ecoboost white smoke just after startup - YouTube 

 

[tomshepp]

No, it's condensation. It takes time to heat the exhaust up enough to turn the water into steam.

[Eng_Ahmad1986]

2 hours ago, tomshepp said:

No, it's condensation. It takes time to heat the exhaust up enough to turn the water into steam.

thank you for considering 🙂 however It doesn't look like water vapour to me !! unless its oil condensation , could it be ?

[Tizer]

I think that is normal and is due in part to the different fuelling and timing required for a cold start and the immediate time afterwards along with emission requirements. 

After reading your post yesterday I had to clear the frost from my side windows this morning so I switched the car on with the door open and quickly went to the back and my car behaved exactly as you described timewise. Different engine though and the temperature was 0c, not 21c.

When the smoke stopped it coincided with when the engine tone changed and the Idle speed dropped to near normal. There was too much noise in your video to tell if your one was the same.

I did not notice any smell, but I lost my sense of smell when I had Covid a few months ago and although I have my smell back I'm not sure if it is as strong as before or not.

If you are worried about oil vapour you could hold a piece of tissue paper over the exhaust to see if there is any residue. I have had old cars with well worn, but not defective engines and oil being burned gives a light blue smoke, especially after putting your foot on the Gas after a long overrun. This has been confirmed because after replacing the Piston Rings and/or the Valve Stem oil Seals, the blue smoke has stopped in all the engines that I have done. 

It does seem strange that your Valve Cover was leaking. Normally you would suspect too much Crankcase pressure and a defective ventilation system, but I think the PCV system is monitored now so I would expect a fault code. Maybe they just did not tighten things up when the other work was done.

[Eng_Ahmad1986]

On 2/1/2021 at 6:52 PM, Tizer said:

I think that is normal and is due in part to the different fuelling and timing required for a cold start and the immediate time afterwards along with emission requirements. 

After reading your post yesterday I had to clear the frost from my side windows this morning so I switched the car on with the door open and quickly went to the back and my car behaved exactly as you described timewise. Different engine though and the temperature was 0c, not 21c.

When the smoke stopped it coincided with when the engine tone changed and the Idle speed dropped to near normal. There was too much noise in your video to tell if your one was the same.

I did not notice any smell, but I lost my sense of smell when I had Covid a few months ago and although I have my smell back I'm not sure if it is as strong as before or not.

If you are worried about Oil vapour you could hold a piece of tissue paper over the exhaust to see if there is any residue. I have had old cars with well worn, but not defective engines and Oil being burned gives a light blue smoke, especially after putting your foot on the Gas after a long overrun. This has been confirmed because after replacing the Piston Rings and/or the Valve Stem Oil Seals, the blue smoke has stopped in all the engines that I have done. 

It does seem strange that your Valve Cover was leaking. Normally you would suspect too much Crankcase pressure and a defective ventilation system, but I think the PCV system is monitored now so I would expect a fault code. Maybe they just did not tighten things up when the other work was done.

my dear thank you very much for considering and this illustrative reply, and thank you also for performing the experiment 🙂 

well today I decided to try what you have stated, I started the after being sat overnight, and I quickly got to the exhaust and held a tissue in front of it, but this time there is no smoke !!!! no smoke at all !!, and of course no residue on the tissue paper, weather temperature this time was 28 , so what do you think about that ? I'm thinking about the valve seals slightly leaking and show themselves in cold weather when its contracted enough to allow the oil to leak, and when its hot outside it doesn't leak, may be its normal and they are designed that way ? or its something else other than valve seals ? or there is nothing wrong at all !!

[Tizer]

 

2 hours ago, Eng_Ahmad1986 said:

my dear thank you very much for considering and this illustrative reply, and thank you also for performing the experiment 🙂 

well today I decided to try what you have stated, I started the after being sat overnight, and I quickly got to the exhaust and held a tissue in front of it, but this time there is no smoke !!!! no smoke at all !!, and of course no residue on the tissue paper, weather temperature this time was 28 , so what do you think about that ? I'm thinking about the valve seals slightly leaking and show themselves in cold weather when its contracted enough to allow the oil to leak, and when its hot outside it doesn't leak, may be its normal and they are designed that way ? or its something else other than valve seals ? or there is nothing wrong at all !!

I would say that it is cold start fuelling related and it was 8 degrees warmer today so probably less fuel was needed and the moisture was less likely to dew out when it hit 28 degree air. In colder climates you often see a horses breath in the winter but not in the summer even though the amount of moisture coming out of it's nose and mouth are exactly the same.

When my car is started from cold the tick over speed goes to about 1200 and instantaneous fuel consumption to about 1 Gallon/Hour. This coincides to when I see the white smoke. It quickly goes back to 850 rpm and 0.1 0r 0.2 G/H and that is when the smoke disappears. I do see the smoke again when I'm driving, when a lot of fuel is being burned, until everything is fully up to temperature.

The Valve Stem oil Seals are substantial rubber things and a tight fit so temperature should not affect them. The Stems and Guides should expand and contract at near the same rate too. The Piston Rings will not seal properly until they are warm so there will be less compression in a cold engine and some oil may be burned but it will be a tiny amount and should not be visible.