5 Causes of Car Blowing White Smoke from Exhaust

If you start up a vehicle with a gas engine and you notice white smoke blowing out of the exhaust pipe, there are a few reasons why this could be happening. One reason for white smoke is very common and completely harmless. But there are other times when white smoke is coming out of your car’s exhaust that you do need to pay attention to as it can be a sign of a major problem.

5 Causes of White Smoke Blowing From Car Exhaust

#1 – Condensation

white smoke blowing from exhaust

This is a common occurrence, especially in colder climates. When it’s cold outside and you notice white smoke at startup, then you probably have nothing to worry about.

When the warm or hot exhaust gases meet cold outside air, condensation and steam is a result. After a short amount of driving, the white smoke should lessen. It’s common for drivers who have lived in a warm climate like California and then move to colder region to worry about this but it’s harmless and perfectly normal.

#2 – Coolant Leak

If you continue to see white smoke coming out of the pipe after the engine has had a chance to warm up or while accelerating, then your coolant might be leaking internally. The most noticeable symptom of internal coolant leakage is when the white smoke is billowing out of the exhaust pipe and leaves a sweet odor in the air. If you the white smoke consistently comes out and the sweet odor smell is present, then it is definitely a problem with your coolant leaking.

The reason why coolant usually leaks is because there could be a crack in the cylinder head or even engine block. Even if the crack is small, the internal coolant can easily leak out and contaminate the oil of your engine. This is how the exhaust smoke ends up turning white. The combination of the coolant and engine oil will create a milky appearance in the smoke. All it takes is for just a little bit of coolant to get into the combustion chamber for white smoke to be produced.

Once you have a low coolant level and a cooling system that isn’t being maintained properly, your engine will begin to overheat. This will cause your head gasket to fail because they won’t be able to seal properly when they’re overheated. As a result, your engine will get worn out much faster and its internal components will get damaged.

#3 – Piston Ring or Valve Seal Leak

symptoms of bad piston rings and valve seals

Leaking valve seals or piston rings are another possibility when it comes to smoke. In this case, bad seals or piston rings cause oil to leak into combustion chamber which then mixes with fuel and burns. The result is a white or light bluish smoke that comes out from exhaust manifold.

If you want to fix this white smoke problem, the easy solution is to take your vehicle to the nearest auto body shop as soon as you notice it. But if you are trying to fix this yourself, never try to remove the coolant reservoir cap with the car still running because the engine will be too hot and it will cause you serious injury. Once the car has had a chance to cool down, check the reservoir and see what the coolant level is at. If the coolant appears to be at the normal level, then you’ll need to have a cooling system pressure checked performed so you can pinpoint where the coolant leaks are coming from.

#4 – Bad Fuel Injector

fuel injector replacement cost

A faulty fuel injector, usually one that is stuck open or is leaking from the o-ring, will deliver too much fuel to the combustion chamber. This excess fuel cannot properly burn in the engine and instead comes out as white or gray smoke out of your tailpipe. Replacing the bad injector (or its o-ring) is the solution.

The hard part is figuring out which fuel injector is bad so depending on vehicle mileage, many mechanics will recommend replacing all the injectors since they’re not very expensive in most cases.

#5 – Incorrect Injector Pump Timing (Diesel Engines)

A diesel engine requires precision timing and fuel pressure of the injector pump. When the timing is not what it’s supposed to be, your engine will essentially be running rich which will cause fuel to not completely burn and instead exit out of the exhaust as white or gray smoke.

 

Comments

  1. Thank you, the info was helpful.
    Is there any lubricant or anything else that can be mixed with fuel or engine oil or coolant to reduce the white smoke emission.

    Thank you!
    JA

  2. So what could be problem when the smoke only come when you start the engine once driving there is no smoke.

    • Also it does not have a sweet smell at the exhaust it smells like gasoline could this be a fuel injection problem? Could it be because the person that put the radiator and just clip the copper part of the transmission cooler line

  3. I recently had my car in for a major repair.
    Its Mini countryman Cooper S with 4WD – it needed a new timing chain and oil pump.
    I had to Take it back to the garage because they hadn’t changed a seal and it was leaking oil. I had also flagged to them that it was intermittently billowing white smoke.
    It appears they did not address the issue with the white smoke from the exhaust.
    It’s intermittent and seems to be most obvious when taking off from a stop, or reversing into a space – so when the engine is under load. I can’t say it’s a sweet smell, but there is certainly a smell!
    Could this just be a bad seal? I know for sure that they are going to awkward as they had real problems with this initial repair – I think they bit off more than they could chew and I suspect they have barely broken even on what was a very time consuming and expensive repair.

    I’d appreciate any suggestions.
    Many thanks

    • It does sound like intake valve seals to me. When idling, the vacuum pressure is higher and you are sucking in a bit of oil. When you give it gas (from a stop or when reversing), the oil gets in the combustion chamber and quickly burns off. It would appear as a blueish/whiteish smoke.

  4. If I start my car it will not show any type of smoke but if I am driving with higher speed or low speed of about 50 km/h it will show a small white smoke emission from the tile end exhuth please I need to know the condition of my car ,remedy and the possible solution

    • I recently just got a new radiator put in my 99 Jeep Cherokee as a new water pump also from overheating when I came back the next day to fix it because I was broke down at the store it would not fire up only with jump start and pumping the gas as soon as jumper cables were taking off car shut off now it will crank over but there is water or fluid coming out of the tailpipe and white smoke what could this be the person that put the radiator in cut the transmission cooler line could this be the reason

  5. So what could be problem when the smoke only come when you start the engine and AC on in idling time 4hour or more, and accelerator pressing white smoke coming.half km driving there is no smoke.

  6. I did the heard and changed the valve stem seals, petrol pump plugs, oil filter and timing belt on a Mitsubishi lance glx 1.6 2004. After that there is a smoke coming out when I start the car and once the engine is warming it died down. What coup be the reason?

    • It’s likely normal due to some oil that got on parts. You should notice less and less smoke until it final burns off completely.

  7. When I accelerate my car (Mitsubishi Galant), often miss-fires and a puff of white smoke comes out…then she takes off.
    I recently had the oil pan replaced and the guys told me my spark plugs, timing belt, and some pump need replacing too. Will this solve issue?

  8. Hi my mini one seems to smoke when it gets up to temp and idling but not when driving and it’s not overheating and there are no warning lights present . Should I be worried ?

  9. I have a ford mondeo 2.0 diesel. Every now and again about once every 3 weeks or so I have either smoke pouring from the engine for about 2 minutes if I am stationary or if I am moving the car coughs a little and I get plumes of white smoke from the exhaust for about 5 seconds then it all clears. I have no other issues and dont lose any oil and it is serviced very regularly but the smell from the smoke in the engine is burning oil. Like I say it’s not constant but worrying and there is no oil on the floor at all

  10. My 2008 GMC Sierra has 180,000 miles. I crank it up in the morning and it’s white smoke really bad that comes out but burns off fast. If I park it say 3 hours it will smoke but less.

    • Check your oil level. You probably have a small oil leak in the combustion chamber which burns off from the heat after starting the car. The longer the car sits, the more oil drips in there so you have more smoke. This is assuming the smoke is a white/blue-ish color.

  11. when i start my car the the car accelerates low and sounds like its struggling after it blows out the grey smoke it then goes back to normal? what do i do to fix it…

  12. I just recently put a used motor in my SUV 04 Land Rover,due to the other one having a crack in the engine block. The older engine was leaking coolant in the oil so bad that water would even flow out of the tail pipe, especially if you revved up the engine. Of course the oil was white where the coolant was mixing with it. Now I have what seems to be a good motor put in it after about 8 months. It seems to run well and in checking the oil, there is no coolant mixing. However, when the engine gets warmed up, it does begin to blow out some white smoke. Depending on how it sits some times it is thicker or really thin. I drove it down the road and did not see any smoke. When I drove it back and turned around, it blew out some white smoke. I revved it up some and it seemed to thin out and at times seemed to almost stop smoking.
    Could this be some coolant/moisture that is still setting/puddled up in the muffler and exhaust from the previous motor and once the system gets hot, it is evaporating the left over water? The motor runs smoothly during this whole time.

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