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White Smoke From The Exhaust On Startup – Here’s What You Need To Know

White Smoke From The Exhaust On Startup

Your car’s exhaust system is the piping that functions to guide the gases away from the internal combustion process within your engine, making sure that the engine is not filled with burnt fuel or burnt vapors, causing excess friction and overheating. If this is not working properly or you notice strange-colored smoke coming out of the exhaust on startup, this is a sign that you need to fix something right away. 

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Causes of white smoke from exhaust on startup


No driver wants to start their car and have strange colored fumes coming from their exhaust while their car is running. If you start your car by turning the key in the ignition for your vehicle with a gas engine and notice white smoke billowing out of the exhaust, there could be a few reasons why this probe occurs. 


Certain reasons for this happening are minor, and that can be easily fixed without any complications. However, there are some other reasons why white smoke is coming out of the exhaust from startups that are much more serious and can lead to other future issues.


  • Condensation


If you live in a certain climate, especially colder climates, condensation can build up on your vehicle’s windows and internal parts. Suppose it is cold outside and you notice white smoke from exhaust on startup. In that case, this is probably a minor issue that just happens due to the circumstantial situation, but not because of any internal problem.


However, if white smoke from exhaust on startup occurs when there is a warm climate, then this is something you need to look into. 


  • Coolant leak


If you see white smoke from the exhaust on startup after the engine has already warmed up and you have been driving for a few minutes, then this is a sign you could have a coolant leak in one of the pipes or engine in your car. If the coolant leaks, the engine will not be able to cool itself or provide the proper lubrication for the parts, leading to overheating and an excess reaction.


The most noticeable symptom of coolant leaking in your car is that white smoke comes out of the exhaust pipe and leaves an odor that is noticeable to both the driver and passengers. If you see the white smoke coming out of the exhaust while you smell something sweet, this can directly be traced back to your coolant leaking in your vehicle. 


The main reason you might have a coolant leak is that there could be cylinder head damage or internal engine issues. The cylinder head is placed above the cylinders on the cylinder block, housing components like the intake and exhaust valves to help circulate the necessary coolant. 


Even if a crack in one of these parts is small and minimal, it can still cause coolant to leak out and contaminate your engine’s rest, leading to white smoke from exhaust on startup. 


Once you notice the coolant leaking in your vehicle and the coolant level is declining in your vehicle, your engine will soon overheat since the temperature will be too high, and the friction will be excessive. This will cause head gasket failure since your engine will not be able to sell property, leading to coolant leaks and internal damage. 


  • Piston ring or valve seal leak



If you find that your valve seals are leaking or piston rings are damaged, this can lead to white smoke from exhaust on startup. If this is the case, the oil will leak into the combustion chamber where the oil will mix with the fuel and disrupt the precious air to fuel mixture ratio within the internal combustion engine. This will cause white smoke from the exhaust on startup.


If you want to fix the problem of the piston ring or valve seal leaking in your vehicle, you should bring your car to the mechanic as soon as you notice the white smoke coming out of your car after startup. If you want to do this yourself, you can check the oil reservoir and the coolant reservoir to see the liquid levels and see if it is normal. If not, then you know where the liquid is leaking from. 


  • Damaged Fuel Injector


A faulty or damaged fuel injector, like one that is permanently stuck in the closed or open position, will not deliver the correct amount of fuel to the combustion chamber – either it will deliver too much, or it will deliver too little, disrupting the air and fuel mixture. If it delivers too much fuel, this excess fuel will not be able to burn properly in the engine to combust at the right time, leading to white smoke from the exhaust on startup. 


The best way to fix this damaged fuel injector or o-ring is to replace the bad injector or the o-ring by figuring out which injector is bad depending on the vehicle mileage and the mechanism’s current condition. This is usually pretty easy to find and easy to do since the fuel injectors are not very expensive in relation to other parts you might need to repair or replace. 


  • Incorrect Injector Pump Timing


In diesel engines, you need perfect ignition timing and the fuel injector pump’s proper fuel pressure to turn the engine on and have it turn properly. When the timing is off, too early or too late, your engine will be running rich and have a rich mixture, causing the fuel to not burn completely and cause white smoke from the exhaust on startup.


  • Transmission Fluid


If you notice white smoke from the exhaust on startup, this means that your car engine is taking on too much fluid from the vacuum pipe or the hose, meaning that your car will be burning excess oil and causing a burnt smell that is noticeable to the drivers and passengers. 

How to fix white smoke from exhaust on startup


In order to quickly fix the white smoke from the exhaust problem on startup and prevent the issue from spreading to any other parts, you can try to do this fix at your own home with the proper tools or bring your car to a trusted mechanic to diagnose the white smoke issue.


  • Inspect the intake gasket


Inside of your car, there is a gasket that seals the manifold to the head. The manifold and the gasket distributes the mixture of air and fuel within the vehicle, along with transporting the necessary cooling fluid to the intake port to cool down the mechanism. This intake port and the other ports are placed on the cylinder heads – however, if one of these parts becomes damaged over time, the coolant will leak into the port and combustion chamber. 


In order to fix this leak of the intake ports, you will have to remove the intake manifold. If there is any visible damage to the manifold or the intake gasket, then you know this is the part that needs to be repaired. However, if the intake manifold and intake gasket are not causing the white smoke from the exhaust on startup, then you need to continue troubleshooting the issue.


  • Examine the head gasket


You only move to this step if you have determined that the intake gasket is working correctly, and there is no visible damage to his part. If there is damage to the intake gasket, then this part is most likely the culprit as to why you have white smoke from exhaust on startup.


If you find that the intake gasket is working correctly, you need to move on to the head gasket. This part seals the cylinder head to make sure the coolant does not leak and gets to the cylinder. If there is any damage or leaks in the liquid lines that are transporting the necessary coolant and oil, this part will cause the coolant to leak into the chamber, creating white smoke from the exhaust on startup.


If the head gasket is fine and the seals are tight without any leaks, then the next part you have to check is the cylinder.


  • Cracks in the cylinder head


The cylinder head is prone to breaking if the car is overheating and there is excess friction between metal parts. However, you need to keep this part in a safe and working condition since it is connecting the engine block and hit head gasket, forming a transportation bridge between these two parts. If this part becomes broken or damaged, you have to replace the cylinder head, which can be quite costly. 


The cylinder head replacement cost will run you at least $500, including labor and parts. If you were going to replace the entire head, it would cost between $200 and $#00 just for parts if you feel like you can do the installation yourself or if you want to find another mechanic. With labor being between $90 and $100 per hour for this part’s fix, the total price will come to at least $500 depending on your vehicle’s make and model. Keeping the cylinder head in working condition can prevent white smoke from exhaust on startup. 

What causes white smoke from the exhaust when idling?


In comparison to white smoke from exhaust on startup, you can also experience white smoke coming from your exhaust pipe while your car is idling. If this is the case, your combustion chambers might be struggling to work properly since they have gotten oil inside, causing them to burn off the exhaust and leading to wasted fuel. This burning of the oil can cause white smoke to appear with rough idling.


This problem is easy to recognize since there will be a different feeling of gasoline exploding and burning oil exploding, leading to white smoke from exhaust occurring. This problem should be fixed as soon as you can since the longer oil sits in your vehicle, the more parts it can damage, like spark plugs. 

What causes white smoke from exhaust smells like gas?


Drivers have to know the differences between the various types of smoke that can appear in your car or from your exhaust. Usually, the smoke coming out of the exhaust pipe will be water vapor or steam. For that reason, you might experience extra condensation and water coming out of the tailpipe due to a head gasket leak or water in the fuel tank. 


Although you might think that this is part of your car’s normal operation, this can be the result of engine misfiring and pushing out the excess fuel that has not been used. This can cause white smoke from exhaust on startup and noticeable fuel smell. 

What causes white smoke from the exhaust when accelerating?


If you notice that your car is producing white smoke from exhaust on startup and while accelerating, the reason could be transmission fluid or burning coolant. If the problem is the transmission fluid, the engine is taking in fluid through the vacuum hose where it shouldn’t be, causing the exhaust to have a burning smell and a white-colored smoke. 


To diagnose if this is the problem, you can test the cooling system by performing a pressure test to see if your engine is overheating or if you have a leaking head gasket. To prevent white smoke from exhaust on startup and while accelerating, you might need to replace the leaking gasket to prevent any future issues. 


If the fluid is the problem, you can replace the vacuum modulator valve or restore the fluid level to the proper height so that it can be used throughout the car efficiently. 

White smoke from exhaust diesel engine vs. petrol engine


  1. Diesel – The white smoke’s diagnosis was coming out of the exhaust on startup for your diesel engine is due to leaking coolant or water dripping into the combustion chamber. The most common cause of the leaking coolant within your diesel engine is a damaged head gasket or a cracked cylinder head. 
  2. Petrol – In this type of engine, the way to diagnose the white smoke from exhaust on startup is incomplete air and fuel mixture. The most common causes of the incomplete mixture is an improperly-working fuel injection system, incorrect fuel injection and valve timing, engine overheating and excessive friction, and a damaged fuel or injection pump.


If you notice white smoke from exhaust on startup, this could be due to many internal engine issues. By fixing the white smoke billowing from your exhaust, you can prevent future fuel problems, fuel injection system issues, engine repairs, and transmission issues from a build-up of unburnt fuel and vapors. 

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