Car Smoking From Exhaust Pipe?

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Reader Question

My car frequently smokes from the tailpipe; does this mean I need an engine overhaul?

Thank you, Don.

 

Dear Don,

Good question Don. Smoke coming from the tailpipe is not good news, but does not necessarily mean the engine needs rebuilding. First, you need to determine what color of smoke is coming from the tailpipe.

The three most common colors of smoke that can be emitted from the engine and billow from the tailpipe are as follows:

White smoke:

White smoke is caused by water and or antifreeze entering the cylinder, and the engine trying to burn it with the fuel. The white smoke is steam. There are special gaskets (head gaskets are the primary gaskets) that keep the antifreeze from entering the cylinder area.

The cylinder is where the fuel and air mixture are being compressed and burned. Any amount of antifreeze that enters this area will produce a white steam that will be present at the tailpipe area.

If white smoke is present, check to see if the proper amount of antifreeze is inside the radiator and the overflow bottle. Also check to see if antifreeze has contaminated the engine oil. You can look at the engine oil dipstick, or look at the under side of the engine oil filler cap.

If the oil is contaminated with antifreeze, it will have the appearance of a chocolate milkshake.

Do not start the engine if the oil is contaminated with antifreeze, as serious internal engine damage can result.

How did antifreeze get in the oil or cylinder in the first place? The engine probably overheated and a head gasket failed due to excessive heat, thus allowing antifreeze to enter the cylinder (Where it is not meant to be).

Blue Smoke:

Blue smoke is caused by engine oil entering the cylinder area and being burned along with the fuel air mixture. As with the white smoke, just a small drop of oil leaking into the cylinder can produce blue smoke out the tailpipe.

Blue smoke is more likely in older or higher mileage vehicles than newer cars with fewer miles.

How did the engine oil get inside the cylinder in the first place? The car has many seals, gaskets, and O-rings that are designed to keep the engine oil from entering the cylinder, and one of them has failed.

If too much oil leaks into the cylinder and fouls the spark plug, it will cause a misfire (engine miss) in that cylinder, and the spark plug will have to be replaced or cleaned of the oil.

Using thicker weight engine oil or an oil additive designed to reduce oil leaks might help reduce the amount of oil leaking into the cylinder.

Black Smoke:

Black smoke is caused by excess fuel that has entered the cylinder area and cannot be burned completely. Another term for excess fuel is “running rich.” Poor fuel mileage is also a common complaint when black smoke comes out of the tailpipe.

Black smoke out the tailpipe is the least cause for alarm. Excess fuel will usually effect engine performance, reduce fuel economy, and produce a fuel odor.

How did the fuel get into the cylinder in the first place? Some of the causes of excess fuel are a carburetor that is out of adjustment, a faulty fuel pump, a leaky fuel injector, or a faulty engine computer or computer sensor.

If black smoke is present, check the engine oil as in the white smoke example to make sure excess fuel has not contaminated it. Do not start the engine if a heavy, raw fuel smell can be detected in the engine oil you can do internal damage and possibly start a fire,  I’ve done it before :()

Call your mechanic and advise him of what you have found.

I hope this helps you determine what could be causing your engine smoke, and the possible reasons behind the smoke.

Blessings,

Austin Davis

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Posted in: Oil Leaks

About the Author:

Austin Davis, consumer car repair advocate. "Hi there! I love to help people solve their car repair problems and I hope my site was helpful to you today. Thank you for stopping by."

29 Comments on "Car Smoking From Exhaust Pipe?"

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  1. Sorry for my delay Ken, been swamped with questions lately. BLUE smoke is usually due to burning engine oil inside the cylinder (s) so I would probably start with pulling the spark plugs, and looking for a plug(s) that are black with engine oil, then on those cylinders do a compression test to see if the compression in those cylinders matches the others. Using thicker weight engine oil might help slow down the oil burning, as well as making sure the PCV system is working properly and allowing the engine to breathe.

  2. ken says:

    Hi,
    i reside in Kenya in Eastern Africa Region.
    my 1997 Mitsubishi galant (GDI)runs just fine.
    However recently there is blue smoke with a slight choking smell out of the tail pipe that comes and goes.
    recently i was travelling for a long distance and at some point the car could not accelerate(engine miss if i could call it so).
    after arrival and parking overnight i traveled the same distance back home with no hitches at all.
    kindly would you assist me in knowing what might be wrong.
    ed.
    your support is highly appreciat

  3. Thanks Dave!

    Did you have to add any coolant to the radiator? Do you have any engine oil leaks that might be running down on the hot engine producing smoke under the hood? How about the brakes? I have seen front brake calipers stick and cause the pads to stick to the brake rotors while you are driving and cause the pads to overheat…and produce smoke and a strong odor. Check to make sure one of the 4 wheels is not significantly hotter than the others after you have driven around for a while.

  4. Dave Snider says:

    Hi Mr. Davis,

    I’ve got a quick question.
    We’ve I got a 2002 F-150 4×4 with about 145,000 miles.
    It runs great and has been very loyal to us. Lately, after a ride around town running errands or going out to dinner, we come home and pull into the garage. I step out of the truck and the 2 car garage is filled with lots of white exhaust smoke. It appears fine when we’re driving around and every year it passes inspection with flying colors. Would you have an idea why I step out into a cloud of smoke when I exit the vehicle? I will check the radiator fluid after I send this question to you.

    Thanks for your time and knowledge.

    Dave

  5. Sure thing Robert, although before you do anything get a cooling system pressure test to rule out an EXTERNAL leak. I get tons of emails each day about headgaskets and more than half are NOT a head gasket problem. I have two videos here I want you to watch.

    http://www.trustmymechanic.com/auto-repair/4429/head-gasket-sealer-try-this/

    Let me know if you need more help

    Austin

  6. robert says:

    I have a headgasket leak, would like to know your great alternative to costly repair.

    I have a 2000 honda civic with over 230,000 miles. I lose about a quart or more of radiator fluid about once a week. I do notice white smoke every time I start up, but it (majority) of smoke disappears after 2 minutes of warmup. on warmup I have to slightly press the gas, otherwise I will have misfiring, I think this is cause I have radiator fluid in one or more of the cylinders, after warm up the car runs fine and idles regularly around 675-760rpm. hope to get this car to last another 12 months, so I can save enough for a downpayment on another car. would love to know your alternative repair method, thanks

  7. Hi Charles,

    Hummmm, sounds weird for sure. 160,000 on one of the vehicles does not concern me too much they are well built and have a great service record. The mifire code, yes it can be a problem with an injector, either dirty or just faulty internally. This does not concern me that much either since its not a constant issue.

    Now, the noise and possible smoke does concern me and I would advise you not start or drive it but have it towed to your mechanic for inspection as to not do any more damage.

    Hopefully this is something external like the water pump broke and the belts are off….check for that. Since you did not mention overheating hopefully this is not an internal coolant leak issue like a blown headgasket. Check the engine oil level, is it full and clean looking?

    If the fan belt is still connected, then we need to start thinking of internal items that would cause the noise….oil pump failure, cam or crankshaft failure etc.

    I would rather not place any fear in your head at this point, so start with the basic stuff, belts attached, all vacuum hoses and wire connections attached? Can you see any oil or coolant leaks etc. etc.

    Get back to me if you find anything out yourself, or when your mechanic has time to diagnose this and we can see if you have any options available to you.

    Austin

  8. Charles S. says:

    Hi. I have a 2006 Ford Explorer with 160,000 miles on it. Every once in a while it will miss when I start it. I can drive it a mile or 2 and turn it off and restart it and it runs like a charm. My check engine light comes on and I had it hooked up to a computer….it says “cylinder 1 misfire”. I changed the spark plug and the coil. Neither one fixed the problem. It doesn’t do it all the time…just on occasion. I figured it had something to do with the injector probably. Last night while driving, it was running fine and all of the sudden it started making a horrible sound like it had no oil…like metal to metal and it died. I pulled over and when you tru=y to start it..it will rev way up and then die. Also, white or blue ( it was dark) smoke will boil out of the tailpipe. The inside of the tail pipe looked like it had a watery substance in it. Any idea what may have happened?

  9. Thank you for your comment Christopher, you made my day.

  10. christopher says:

    Dear Austin Davis,

    Just wished to let you know that reading this site is really helpful for me. At least I now know the reason of the white smoke from my car. TQVM….from the bottom of my heart!

  11. Austin Davis says:

    Welcome, same to you.

  12. Gantulga says:

    Its engine cold.thank you for everything.Good luck to you.

  13. Austin Davis says:

    Are you sure this is BLUE smoke from burning oil (are you adding engine oil regularly) or could this be a more BLACKISH colored smoke due to running rich, too much fuel. If this vehicle has a carburetor, maybe you have a choke problem which would happen when engine is cold and the smoke is a darker black color due to unburned fuel?

    Even fuel injected vehicles have a cold start injector or cold start function to help start the engine in cold weather.

    I dont really think blue smoke issues would cause the engine to die, unless there is severe internal engine damage causing loss of compression.

  14. Gantulga says:

    there is 1 misunderstanding.My car not stop by itself.
    When blue smoke comes up.
    I stop the car.
    then restart everything normal for few minutes.
    today smoke comes up 1 time.
    Yesterday 3 times.

  15. Gantulga says:

    Thank you very much.I have no garage.Then I thought car is cold something like that.Is this possible

  16. Austin Davis says:

    If its BLUE smoke you see then you are consuming (burning) engine oil in the cylinders. If the smoke seems to happen more so when you come to a stop than when you are driving I would suspect a problem to be more so in the cylinder head (like valve stem seals) than due to wear in a piston ring.

    You might want to try using thicker weight engine oil (since it gets very cold there, you can’t use too thick of oil weight) like maybe a Castrol 20w-50 and an oil additive called Engine Restorer, to help slow down the consumption. It might never go away completely without doing internal repairs to the engine but might reduce it enough where it is livable.

    Here is a link to their product page for more information
    http://www.restoreusa.com/faq.html

    You might have to order it on ebay or amazon if you can’t find it locally.

  17. Gantulga says:

    Hi my name is Gantulga im from mongolia
    My car is Sang yong Actyon 2009
    The problem is blue smoke
    when i drive and stops its coming out
    Early in morning
    2-3 times coming out
    I havent get my winter oil yet
    what is the problem
    Thank you

  18. Austin Davis says:

    I would suspect you have worn out valve stem seals in the cylinder head. Stem seals tend to leak oil when the engine is off and sitting up. When you start the engine after it sits the cylinder and spark plugs have to burn off the oil that has seeped into the cylinder, thus the blue smoke….from burning oil. The correct fix is to remove the cylinder head and do a “valve job” but that is very expensive.

    You might try using a thicker weight engine oil, like Castrol 20W50 weight and see if that slows down the oil seep. Also have a mechanic check the PCV system, which is what the engine crankcase uses to breathe. If the engine can’t exhale properly it puts extra pressure on seals and o’rings.

    If this smoke is more of a black color, it could be from fuel dripping into the cylinder and having to burn off causing more of a dark blackish smoke with a raw fuel smell to it. Leaking fuel injectors and or fuel pressure regulator are common causes.

  19. Clifford Strain says:

    Hi, I have a peugeot 207 1.6hdi with 72k miles on it. Each time I start it up, there is a lot of blue smoke and it smells very strong. Its lumpy but after 10 secs it seems to clear

  20. Austin Davis says:

    Thank you very much Felix

  21. Felix L Valenzuela says:

    i’ve red one of many reasons regarding smokes on engine…thank you veru much sir,as it really helps a lot.
    Keep up the good work and may the good Lord bless you,sir.

  22. Austin Davis says:

    I would get a mechanic to read your computer codes and investigate what the code is and why it is coming on. There are MANY sensors and things that can cause this to happen. Black smoke is due to excessive fuel inside the engine, so the engine is “running rich” and can’t burn all that fuel. This should be a pretty easy repair once they diagnose the engine light code.

  23. Janelle says:

    Hi My minivan is a 2005 Chrysler t&c it just had cpu replaced because was sputtering or misfiring. It is a month later and it is doing it again. The engine light is on and the gauge will read it is overheating but the van is not really over heating and then it started misfiring with what looks like black smoke coming out the tail pipe please help no one seems to tell me anything or how to go about checking it.

  24. Austin Davis says:

    Well, you could have antifreeze dripping down into that #4 cylinder due to a head gasket leak inside the engine, or you could just have a problem with that cylinder like a bad spark plug wire, spark plug, fuel injector, or ignition coil.

    I think I would get a mechanic to investigate further the misfire, and if you are low on antifreeze inside the radiator I would also get that mechanic to do a cooling system pressure test to see if you have an internal leak (headgasket) or external leak (water pump or hose etc.)

    if you do have a headgasket leak, let me know I can show you a great alternative to the costly repair

  25. Maria says:

    Hi :) My car started to misfire and then white smoke came out of the tail pipe – along with that my car started to over heat and I thought I could smell antifreeze so I ran a test on my car and the test came back showing that the #4 cylinder has a misfire. I guess what I am wondering is what could this be? My cooling system is leaking perhaps? Any information you could give me would be much appreciated, Thank You so much for taking time to read my letter. Sincerely, Maria :)

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