5 Causes of Car Blowing White Smoke from Exhaust

Last Updated on July 5, 2021

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.

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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.

 

83 thoughts on “5 Causes of Car Blowing White Smoke from Exhaust”

  1. Hi, I repaired the car engine. It had a piston ring issue. But the white smoke still didn’t stop. It continues coming from the exhaust and smell like fuel. The repair was done by a repair station. I live in an environment which is like – 15. The repair station said it’s because of the cold. What shall I do? Wait till the summer and see whether it is still coming?

    Reply
  2. I have white smoke coming out of my exhaust and I was told I need a new high pressure gas pump. I am not sure what this is. Is it a fuel pump? Can you give me any information about this because I don’t see this as a common problem as to why white smoke is coming out of my exhaust.

    Reply
    • What year, make, and model of vehicle are you driving? I can’t know if it’s a common issue unless I know that information, because some vehicles are more prone to certain types of failures than others.

      Yes, I assume by “high pressure gas pump” they mean a high pressure fuel pump (HPFP). Direct injected engines typically have a low pressure fuel pump to bring fuel from the gas tank to the engine bay, then a high pressure fuel pump that sends fuel at very high pressures to the fuel injectors, which then inject fuel straight into the combustion chamber.

      I don’t think the white smoke would be caused by a bad fuel pump, but you’ll have to look into the problem a bit more to know for sure.

      Reply
  3. I only have white smoke coming out of my exhaust pipe after the car is sitting running / idling for about an hour and the smoke only comes out when I step on the gas and only does so for about a minute and then completely goes away. This is the only specific time and way the smoke comes out of the exhaust pipe. If I do not sit idling for an hour then nothing happens. any thoughts?

    Reply
    • Do you have a turbocharger? It’s possible the cooling lines in the turbo are leaking a bit. You could perform a leak down test to help you eliminate bad head gaskets as a possibility. Any other symptoms? Does the issue affect the car’s drivability?

      Reply
  4. My 1993 acura legend has white smoke blowing from the exhaust and green liquid in the engine. Big old cloud of white smoke when the car turned on. Is it a bad water pump or blown gasket?

    Reply
  5. My 2012 Nissan Qushqai is pouring smoke when ever I turn it on and accelerate I don’t know if this is because the dpf not cleaning properly or a coolant leak what do you think I should do?

    Reply
  6. I noticed a white smoke coming out of my golf 3 car, the moment I accelerate it brings out the white thick smoke. Please what is actually wrong with the car,?

    Reply
    • It will be hard for anyone to give you more information than what’s in the article without doing some diagnostic work to narrow it down. You could try doing a leak down test to confirm a blown head gasket. Sometimes a bad intake manifold gasket will exhibit similar symptoms, as will a cracked block or cracked cylinder head.

      Reply
  7. I have a 2000 chevy tahoe 5.7l i can drive it for about an hour or so. When I stop at a light after that time frame it begins to smoke. When I press the accelerator pedal and take off it goes away. I’m wondering if it could be my head gasket or a bent vavle

    Reply
  8. Hi.
    I have a -03 Passat 1.8t. Got a problem where I couldn’t Rev more then 3000 and before I was able to stop I noticed a big cloud of white smoke from the exhaust. When checking for faults I found a broken vacuum hose to my turbo and that the “fan” in the turbo was loose. Change the turbo now, got about 500m before the white smoke came back. Coolant is ok, oil ok. Smoke smells a little burnt. Got any idea?

    Reply
  9. My car smoke in the morning when start it up real bad I can’t see out my back window for about 5 minutes after that it’s OK it do this every morning real bad

    Reply
    • There are a number of things that could cause smoking, particularly on startup. You may have a head gasket or intake manifold gasket leak and are burning coolant.

      Reply

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