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First, sorry if this is a duplicate. I searched for similar symptoms on this site and found no other issues where the problem went away on its own.

Yesterday after five minutes of neighborhood driving, I accelerated after a right-turn-on-red (so accelerating a little heavily) and saw a great deal of white (maybe blue) smoke coming out of my tail pipe, and at the same time experienced a loss of acceleration (or perhaps my transmission shifted in a strange way, I'm not sure) then the smoke was thin (almost none) and the acceleration returned to normal.

I drove home (a few blocks) let the car sit for a few hours and then took it for a spin to see if there was any smoke. There was none.

I drive a 2013 Hyundia Elantra sedan with automatic transmission.

Why would I get a lot of smoke out of my car, and then the smoke goes away? All of the issues I've read about do not seem like problems that would go away.

Edit: The mechanic replaced a PCV valve that was stuck open. An answer listing this as one of the possible causes and an explanation can get the bounty.

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  • There is still coolant in it isn't there? The smoke would stop when the coolant level has dropped significantly but total engine failure would shortly ensue.
    – Steve Matthews
    Commented Sep 16, 2016 at 14:25
  • I have coolant, and oil. But the PCV valve vents the crank case which has oil in it doesn't it?
    – OrangePeel52
    Commented Sep 16, 2016 at 14:38
  • PCV operation explained A partial stuck or intermitiant value can introduce excess air flow into the intake and pull oil up into the intake.
    – spicetraders
    Commented Sep 16, 2016 at 17:12
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    That would cause blue not white smoke.
    – maplemale
    Commented Sep 16, 2016 at 17:33
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    Yes post said white maybe blue.
    – spicetraders
    Commented Sep 16, 2016 at 20:23

3 Answers 3

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+50

Per your edit, you said the mechanic replaced a PCV valve that was stuck open, causing the excessive smoking. PCV in this case stands for Positive Crankcase Ventilation. The valve is located on the side of the engine block, and serves to vent excess pressure out of the crankcase. The pressure is created by the churning and heating of oil, as well as some of the combustion gasses escaping past the piston rings into the crankcase (known as blow-by).

Because the extra pressure in the crankcase often contains atomized oil and in some cases un-burnt fuel, the PCV valve routes these gasses back into the intake plenum, such that they can be used in the combustion cycle and exhausted out the tailpipe. When your PCV valve was stuck open, the hard acceleration excited and heated the oil, and the higher levels of blow-by caused by high engine RPM allowed (relatively) large amounts of that oil through the valve into the intake plenum, causing the white smoke you saw. It does not take much oil to create a large cloud of smoke, so you may not even notice the oil level went down if you were to check the dipstick.

For more information see this link provided by @spicetraders

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  • What about cars with no "valve", mine just has a tube connected from the valve cover to the throttle body, would that not make the engine constantly consume oil? would the engine benefit from an after market pcv valve?
    – method
    Commented Sep 19, 2016 at 15:21
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    @method read the link PCV operation explained. Next to last paragraph on no PCV engines restrictor
    – spicetraders
    Commented Sep 19, 2016 at 15:57
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    @method If it's routed from the valve cover then it's not a PCV valve by definition. The valve train will have much less exited/atomized oil, and hopefully no fuel in it. Either way, the PCV is strictly an emission control devise, so an aftermarket system won't benefit the engine.
    – MooseLucifer
    Commented Sep 19, 2016 at 15:58
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White smoke is usually antifreeze burning. That indicates a crack in the head gasket. Blue smoke is burning oil. That could be a number of things from piston rings to valve guides . When you burn it off it disappears.

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  • by 'burn it off' do you mean burn off all my oil/coolant? or just a little? I will check my levels but i only had thick smoke for 10 seconds, not enough time to burn a lot of fluid i think. And why would more not leak the next day, making more smoke?
    – OrangePeel52
    Commented Sep 6, 2016 at 15:35
  • It is a small leak and will take time to fill in your combustion chamber and when it does the problem will reoccur.
    – Old_Fossil
    Commented Sep 6, 2016 at 15:41
  • Would i see smoke the next time i drove the car, after letting it sit over night?
    – OrangePeel52
    Commented Sep 6, 2016 at 15:48
  • probably .....check with @Pete he seems to agree with me about the head gasket . A 3 year old car is on warranty. Have Hyundai change the head gasket for free.
    – Old_Fossil
    Commented Sep 6, 2016 at 22:52
  • I'm not 100% sure, but wouldn't there be coolant in the oil with a potential head gasket leak? The coolant would go to the bottom of the oil pan. I good check might be to drain a tiny amount off the bottom of the oil pan and see if it's water/coolant?
    – maplemale
    Commented Sep 16, 2016 at 17:35
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White smoke is water in the cylinders, and your symptoms are classic of a Head gasket failure.

If the car is still under warranty (quite likely with a Hyundai), take it to the dealer; otherwise you're looking at the wrong end of a $1,000 bill.

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  • While you are wright about those symptoms, I doubt a 3 year old car will suffer from head gasket, moreover to that, it would be a repeated issue with other indications as well.
    – Alimba
    Commented Sep 16, 2016 at 21:58

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