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10 Causes Of White Smoke From Exhaust On Startup Revealed


White smoke exiting from the exhaust system when you start your car’s engine can be caused by several issues. Several are minor, and no cause for worry, but others are much more serious and, if not dealt with, could ruin your engine. Also, the length of time white smoke is exiting the exhaust systems can be an indicator of how serious the situation is.

In any case, don’t hesitate, have a professional mechanic examine your engine and correct the problems before the engine is damaged and repairs run into thousands of dollars. If you notice white smoke from exhaust on startup, verify the source. This post reviews a few of the potential reasons what thick white smoke means when the smoke is coming from the exhaust pipe.

10 Causes White Smoke From Exhaust on Startup

Do not take white smoke like it is a joke.

The following are the top most common reasons car owners may observe white smoke from exhaust on startup of their vehicles.

1. Internal Coolant Leaks

Coolant circulates within the engine to cool it and keep it at the optimum operating temperature. Small leaks within the engine allow coolant to enter the combustion chambers and produce white smoke to exit from the exhaust.

For example, gaskets that seals the cylinder head may be leaking. There may also be a sweet odor to the exhaust, which indicates that liquid is being converted to steam in the engine and pushed out through the exhaust.

Verify the coolant level in the radiator reservoir. Low coolant levels could lead to overheating and produce even more serious problems with the engine as it overheats.

2. Bad Piston Ring

The piston rings typically provides the seal between the combustion chamber and the crankcase where the engine oil resides to lubricate the engine. A bad piston ring can allow the oil to slip past the ring into the combustion chamber. The oil disrupts the air to fuel mixture and may cause black or white smoke to exhaust from the tailpipe.

Check the motor oil level and all other fluid levels. Low levels of either fluid can lead to overheating and low oil levels to poor lubrication of the engine components, potentially causing serious damage.

3. Valve Seal Leakage

The intake and exhaust valves are both inside the cylinder head. The liquid circulates inside channels in the cylinder head to cool the cylinder. Leaking liquid or a damaged valve can allow coolant into the chambers of combustion, which is converted to steam and creates white smoke or steam exiting from the exhaust.

Car owners can drive their cars in this condition. However, more damage may occur if the engine overheats or additional components crack. Have your motor checked by a pro mechanic. You might need to pay a bit more attention if you notice this problem combined with a burnt smell.

4. Condensation Issue

Condensed air sometimes builds up in the exhaust systems while the vehicle is not being used, especially in cold climates. Hot gases exhausted from the engine cause the normal condensation to evaporate and be expelled from the tailpipe as steam.

Car owners may also notice water dripping from the tailpipe when starting the car. This is a common occurrence, and the white smoke or, in this case, steam will disappear once all of the water vapor has evaporated, normally after a few minutes of driving. This is one of the most common causes of white smoke from the exhaust when starting your car.

5. Bad Fuel Injector

Bad fuel injectors, usually stuck in the open position, can allow too much fuel to enter the combustion chamber. The air to fuel ratio is disrupted, leading to some unburnt fuel exiting the exhaust pipe in a cloud of grey or white smoke.

There is an injector for each cylinder, and it can be difficult to figure out which one is the problem. Many mechanics will suggest that all fuel injectors be replaced.

A bad fuel injector is a simple fix and one of the cheapest solutions to white smoke coming from exhaust on startup. Car owners can just get a new one, which eliminates the problem.

6. Incorrect Injector Pump Timing

Timing of the fuel injectors is critical to ensure that the correct fuel to air mixtures enter the combustion chamber and all of the fuel burns. Poor timing can cause too much fuel to enter, which could cause some of the fuel to exit from the exhaust unburnt as white or gray smoke.

Operators may notice a decrease in power from the engine and perhaps increased fuel consumption above normal levels if the injector pump timing is off.

7. Damaged Fuel Filter

A damaged or clogged fuel filter usually does not cause white smoke from the exhaust pipe. The fuel filter is preventing sufficient fuel from reaching the fuel pump and the motor.

This leads to lower power levels, poor acceleration, misfiring, stalling, check engine light illuminating, difficulty starting the automobile, and possible damage to the fuel pump injection unit.

8. Cracked Cylinder Heads

A warped or cracked cylinder head can allow coolant into the chambers, which is then heated and expelled out the tailpipe as steam or white smoke. Leaking coolant can lead to low levels of the liquid and overheating of the engine.

An overheated engine can cause additional damage to the cylinder head and even warping of the engine block. Check your coolant level, top-up if needed, and have your engine checked by a professional mechanic.

9. Head Gasket Failure

Faulty coolant and head gaskets can fail due to overheating, age, or defects leading to leaks of liquid into the engine. White smoke from the tailpipe and low levels of coolant are indicators of a failed head gasket.

You may also notice a change in power levels if too much air is allowed into the system. Unfortunately, head gaskets are some car parts that may need to be replaced with time due to normal wear specially if you notice a smell like burned oil.

10. Engine Oil Leak

Engine lubricants can also leak into the combustion chamber caused by bad piston rings or a cracked cylinder head. The oil will be partially burned before exiting from the exhaust as a white, gray, or dark cloud of unburnt gases.

Engines with burning oil can lead to low levels of oil in the crankcase leading to poor lubrication and overheating. Significant damage to the engine can occur if this situation is not repaired, and oil levels are maintained.

Difference Between Black Smoke and White Smoke from Exhaust On Startup

White smoke is usually caused by condensation or coolant heated to a level causing steam to exit from the tailpipe. Blue smoke usually indicates oil is being burned. Gray smoke can also be due to an oil leak or a transmission oil leak. Black smoke is usually caused by too much fuel entering the combustion chamber and not completely burned.

White Smoke from Exhaust On Startup: Diesel Engine Vs. Gasoline Engines

White smoke from either motor can be caused by condensation in the exhaust systems as well as leaking coolant in the cylinder head. Always check coolant levels if you suspect a leak to avoid engine overheating.

Diesel car engines depend on optimal fuel injection operation to ensure maximum power levels. Diesel engines with too much fuel in the air-fuel mixture can lead to excess fuel ejected from the exhaust as white smoke.


As soon a car owner see white smoke from the exhaust automatically, they start to worry. They should worry more if they just notice that their car stopped working. White smoke is a common problem and is typically easy to fix.

If you get white smoke on startup, just find time to take your car to a mechanic. Before you do that, read the following questions our readers have with regards to while smoke exiting from the tailpipe of your vehicle.

What is the most common reason why white smoke is coming out from your exhaust?

The most common reason white smoke comes from your exhaust pipe, particularly in colder climates, is condensation in the exhaust system, heated into steam as the car warms up. This is a common occurrence when I start my car. Steam or white smoke should quickly disappear. Once the car engine is at operating temperature, the white smoke should disappear.

Ongoing white smoke emanating from the exhaust pipe usually indicates a leak of coolant into the combustion chambers, which is heated and exits from the tailpipe as steam. Check coolant levels, top-up if needed, and have your engine checked by a mechanic.

Is it normal to have a car with white smoke coming out of the exhaust when idle?

A car motor that is idling after just being started will often have white smoke coming from the tailpipe. This is due to condensation in the exhaust systems and should disappear once the motor reaches its normal operating temperature.

If there is still white smoke coming from the exhaust pipe after the motor has warmed up to operating temperature, it indicates there is something more serious going on, such as leaking coolant, which should be checked. Always top up coolant levels if needed, especially if you suspect a leak somewhere in the system.

What is the main reason for white smoke from the exhaust when accelerating?

White smoke while accelerating can be caused by coolant leaks or auto transmission fluid leaking into the motor. Antifreeze is heated into steam and pushed out the tailpipe, and becomes a white cloud that quickly dissipates.

Transmission fluid can have the same symptoms. However, there will be an oily smell to the exhaust indicating burnt transmission fluid whenever you depress the gas pedal.

Typically costs involving the car transmission are very expensive. Hopefully, this is not the problem that your car has because it would involve a repair that is around $1,300 to $1,500 dollars depending on your car make and model.

Does low coolant level have anything to do with white smoke from exhaust?

Low coolant levels indicate that there is a leak in the cooling system that could be external to the motor as well as internal. If you observe coolant leaking under the motor, then it is probably an external leak from one of the hoses, the radiator, or one of the gaskets.

If there is no external leakage, your coolant level is low, and there is white smoke exiting from the exhaust, there is a pretty good chance that there is a leak somewhere internally. A pressure test will help identify if the radiator has leakage, which could lead to solving the problem by replacing a part.

Always top up the fluid to the proper levels to avoid accidental engine overheating, which can cause added problems. Have your motor checked by a mechanic for a cracked cylinder head, leaking head gasket, etc.

What is the typical replacement cost when you have white exhaust smoke?

The cost of car repairs can vary a great deal based on the actual cause of the problem, the type and model of car or truck, and how quickly you dealt with the problem. Continuing to drive your vehicle with white smoke billowing from the exhaust is only going to make matters worse and potentially result in more damage.

Replacing fuel filters can cost up to $200 while replacing fuel injectors or replacing a blown head gasket can generate repair costs approaching $2000 or even more. Allowing your motor to overheat could also cause a cracked cylinder head or a cracked engine block costing thousands of dollars in repairs.

Can I Drive If I See White Smoke from Exhaust?

Driving when you see white smoke that is coming from your exhaust on startup is not recommended. Don’t just think you have nothing to worry about if you see white smoke. This can be a serious problem, and you need to address it.

Although some of the car parts that need to get replaced cost money, identifying the problem early is crucial when it comes to white smoke from exhaust. Typically problems with white smoke are related to important internal parts of your car, and you need to address this problem fast.

What type of cars get white smoke from exhaust?

We have noticed large diesel SUV’s and trucks having to get a replacement of some parts over time. Some parts like the head gasket seals get worn out, and they need to be replaced. They are also related to transmission fluid leaks that could produce a burning smell.

Other Causes of White Smoke From Exhaust On Startup

A faulty vacuum modulator valve in the car is one of the most common causes of white smoke and disappears once the car engine has reached operating temperature. This is typical when fluid is the problem.

The continuous exhaust of white smoke from the tailpipe is an indicator of more serious problems such as leaking intake gasket or head gasket allowing fluid to enter the combustion chamber. The thickness of the burning coolant smoke can indicate how serious the problem may be.

Check fluid levels and always top up the coolant reservoir if needed. Low coolant levels are another indicator of fluid leakage. Never allow your fluid level to become to reach lower levels that causes motor overheats, which can result in more serious repairs and expensive problems.

Head gasket seals prevent the coolant from leaking into the chambers. So if it smells like burning coolant, then most likely, the problem is within these seals and the need to get fixed. If this happens then, car owners need to remove the intake manifold to fix the problem and require to examine the intake gasket.

When water mixes with gasoline, it causes white smoke, and the car typically smells like gas when you start the car. You want to make sure you prevent the combustion mixture at all times. This is something that every car owner can control by checking the cooling system periodically to try to find a coolant leak.


Start by inspecting the gasket that seals the manifold to the head. If you notice any burned oil, you probably have to take your vehicle to fix the issue. Problems with the head gasket causes white smoke from the exhaust while driving. Most likely, it is burning fluid, and you should fix the problem.

White smoke from exhaust is common on trucks that come with a diesel engine. Over time, the head gasket seals tend to deteriorate and allow coolant to leak into the car chambers. With time if you do not fix this issue, you will notice how the car will start to have more problems.

Have your car checked by an experienced mechanic and make repairs before more serious repairs occur and much higher repair costs. Hopefully, now you understand what causes white smoke from exhaust on startup and the things that you can do to fix the issue.

Last Updated on: July 14, 2022

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