When accelerating, white smoke from the exhaust can be an issue if it continues to smoke and is thick. In such cases, you should get your car checked, as it could be because of some severe problem.

“If the smoke is not thick and disappears within a few seconds, then it may mean nothing because it is common and usually happens due to condensation.”

There are manifold reasons for white smoke from the exhaust. Whether the issue is big or small, you should know what causes white smoke as a vehicle owner.

What is White Smoke?

Before you learn the issues that cause white smoke from the exhaust, let us first understand what white smoke from exhaust means. Whenever you see white smoke from the exhaust, it can indicate a severe problem in your automobile. White smoke can be a result of normal condensation. When condensation builds up in the exhaust system, it can cause thin white steam, like vapor. You should not panic in such a case, as the smoke will disappear quickly.

On the other hand, if the smoke is thicker and lingers longer, a coolant leak can be an issue. This can lead to numerous problems, such as a blown head gasket, cracked engine block, or damaged cylinder head. You might have to incur heavy expenses to resolve such issues. Hence, it would be better to give immediate attention to such problems before they exacerbate.

10 Causes of white smoke from exhaust

As a driver or owner of a car, whenever you see white smoke from exhaust when accelerating, your car might indicate some problem. Hence, you must know what these indications mean and what the causes of white smoke from exhaust are. Below mentioned are some of the common issues that cause white smoke:

1.      Coolant Leak

Coolant is another vital thing required for the smooth working of the engine.

“A car coolant is also called antifreeze; it prevents the car engine from overheating.”

The parts that come in contact with the coolant are also lubricated, thereby protecting the water pump, cylinder, piston timing, head gasket, etc., from any damage. When this coolant leaks, it mixes with the fuel mixture and starts to burn, which can cause white smoke from the exhaust.

Also, when coolant leaks occur, the quantity of coolant is reduced, which can cause the car to heat up and emit white smoke from the exhaust when accelerating. Thus, if you encounter such a situation, fix the issues because overheating can have severe consequences.

2.      Condensation

This is one of the common causes of white smoke from exhaust pipes. Especially in winter, you might notice white smoke from your car’s exhaust. This is because the condensation accumulates in the exhaust pipe, and when these hot exhaust gases come in contact with the cold atmosphere, thin vapor like steam is the result. This smoke would take a few seconds or a minute to disappear and usually nothing to worry about. However, it is thick and lasts longer, then you might have a problem and should get it checked.

3.      Oil Leak

When there is excessive oil in the combustion chamber, it results in white smoke. The engine requires a specific amount of fuel and air to work efficiently, and this fuel mixture should not be too rich or unbalanced. If the amount of air or fuel is more, it would cause a problem. Therefore, when oil leaks in the chamber, the engine will burn more fuel, and this causes white smoke from the exhaust when accelerating.

4.      Cracked Engine Block

An engine block is made of aluminum alloy or iron to support other engine components. The engine block transfers the heat built from the friction to the engine coolant and the atmosphere. A crack in the engine block can cause coolant to leak, resulting in white smoke.

Even a small crack can cause issues, allowing the coolant to mix with the oil. When the coolant burns, it causes white smoke from exhaust when accelerating. So, if you see such smoke, you should get it repaired or fixed immediately.

5.      Cracked Cylinder Head

The cylinder heads control the airflow in and out of the cylinder and govern the amount of fuel deployed. A crack in the cylinder head is caused by overheating, head gasket failure, lack of coolant flow, or coolant leak.

If the engine crack is too extreme, it can lead to drastic consequences, such as terminal damage. Since coolant passages run along the cylinder head, when there is a crack, the coolant can enter the combustion chamber and burn along with fuel. Because of this, white smoke is emitted from the exhaust pipe.

6.      Blown Head Gasket

A head gasket is a part fixed between the cylinder head and engine block. It functions as a seal between these two and prevents pressure loss and engine fluid leaks. It also checks cylinders, pistons, and oil return passages. However, if the head gasket is blown, the pressure is lost as there is no medium to regulate it. Subsequently, your car will lose its power.

Also, a blown head gasket can cause coolant to leak, resulting in white smoke from the exhaust when accelerating. The Head gasket is usually blown when the car is frequently overheated or if you continue to drive with an overheated engine. Therefore, you must ensure that the car’s cooling system works efficiently and is in good condition.

7.      Bad Fuel Injector

A fuel injector is used to inject fuel into the engine. As the engine needs the correct air-fuel mixture to complete the combustion process, this device helps it achieve efficient combustion. It is an electronically controlled device. The timing, amount, and pressure of fuel, etc., are also controlled by the ECU (electronic control unit).

If your fuel injector is bad, it can cause a misfire. It will disrupt the required balance of air and fuel entering the engine. Since the amount of fuel required in the engine is more than it should be, it needs to be burned and expelled, which can cause white smoke from the exhaust.

8.      Error in Electronic Control Unit (ECU)

Electronic Control Unit (ECU) is an electronic device installed in the vehicle.

“It is a microcontroller with embedded software that controls the working of ECU.”

Further, the ECU determined and governed multiple electronic systems in the vehicle. Damage to the ECU can be costly (around $1000-$3000).

The ECU is responsible for the correct functioning of the fuel injector. The ECU governs how much fuel to inject, at what time, and what pressure to apply. If there is a glitch in the ECU, it can cause the fuel injector to inject fuel at the wrong time or inject excessive fuel, which can cause white smoke from the exhaust when accelerating.

9.      Piston Rings Leak

Piston rings support piston movement. Pistons move up and down, so the rings’ job is to support them and aid in their smooth and efficient movement. If the piston rings lose their grip or get worn, they cause an oil leak. When this oil gets into the combustion chamber, it can lead to white smoke from the exhaust pipe.

Bad piston rings or leaks in piston rings can also cause misfiring, which further causes white smoke from the exhaust. If you notice such an issue, it means the piston rings can no longer seal the cylinder. Hence, you should have this issue fixed on time.

10.  Valve Seal Leak

Like the piston rings, the valve seal also controls the oil consumption. Other than this, it also maintains valve lubrication. Engine power loss, popping noise, high smoke, etc., indicate bad valve sets. Like piston ring leaks, if the valve seal leaks, it causes the oil to enter the combustion chamber. If the leak is too much, the oil drips on the hot engine and exhaust manifold, causing smoke. Also, when the engine burns excessive oil, it can result in white smoke from exhaust when accelerating.

How to Fix White Smoke from Exhaust

If you see white smoke from exhaust when accelerating, it could be an issue because of coolant leakage. Follow the following steps to fix this issue:

Step 1: Smell the smoke

The first thing you should check is the smell of the smoke. If it is a coolant leak, the smoke will likely have a sweet smell. If you smell steam or water, then it could be normal condensation. However, if the smell is toxic, it could mean a damaged catalytic converter. So, if the smell is not sweet or just steam, seek professional help.

Step 2: Inspect the Intake Gasket

You need to check the intake gasket and see if it is damaged. A damaged intake gasket can allow coolant to enter the combustion chamber. When the coolant burns in the chamber, it causes white smoke from the exhaust when accelerating. If it is damaged, remove the intake manifold and check the intake gasket. If it is damaged or rusted, repair it; otherwise, replace it.

Step 3: Inspect the Head Gasket

You should only check the head gasket to see if the intake gasket works perfectly. Again, a leak in the head gasket can allow coolant to get into the combustion chamber, causing white smoke. If it is damaged, replace or repair it.

Step 4: Check if there is any crack in the Cylinder Head

If both your intake gasket and head gasket are working fine, you should check for any crack in the cylinder head. Since the cylinder head is made of aluminum, it can be cracked due to overheating. If there is a crack, you have to replace it. There is no other option left in front of you.

Other Color Smoke Emitted by Exhaust

Just like white smoke from exhaust indicates various issues, similarly, there are other colors smokes as well that show or signify other issues. Some common smoke colors are:

Black Exhaust Smoke

As stated earlier, an engine requires a correct ratio of air and fuel mixture, and if this mixture is too rich, it can cause black smoke from the exhaust. This can be caused by a blocked manifold, intake valves that are unable to pass the proper air pressure, or fuel injectors that are injecting too little or too much fuel.

Another reason for this could be a clogged air filter. You do not need to fret, as a clogged filter would not impact your gas mileage, but it would affect the vehicle’s performance. So, if you see black smoke from the exhaust, you should get it checked by a technician, as it is not normal.

Gray Exhaust Smoke

Gray exhaust smoke could also mean an issue with the car. Gray smoke from the exhaust is not regular, so if you notice gray smoke from the exhaust, seek professional help.

Smoke can be grey because of damaged piston rings, worn cylinder walls, or leakage in valve seals. A blown head gasket can also cause gray smoke. The engine might be working extensively, or a coolant leak can cause gray smoke from the exhaust.

Blue Exhaust Smoke

Some people categorize blue and grey smoke together. It also happens that, at first, blue smoke often looks like gray smoke. It would help if you were observant and patient to distinguish the bluish tint in the smoke.

“Blue smoke indicates that your car’s engine is burning lots of oil.”

Again, blue smoke from the exhaust is not normal, and it can be a bad sign and needs immediate attention. It can be caused by damage to internal engine components or issues with the oil. An oil leak is again a common cause of blue smoke. This leak can also be caused by various problems, such as damage to piston rings or valve seal leaks.

Overfilling oil can also cause blue smoke. Overfilling can cause oil to churn and whip, which can cause smoke, which will cause problems like not lubricating properly and causing other similar damages. Thus, ensure immediate attention.

Frequently Asked Questions (FAQs)

Can dirty oil cause white smoke?

There should be a proper mixture of air and fuel; there should not be anything else. If oil enters this chamber for any reason, it can mix with this mixture and cause white smoke. This white smoke will be thick and exit from the exhaust pipe. You should seek professional help to figure out and fix the issue, as ignoring or preventing the repair can worsen the issue.

Can bad spark plugs cause white smoke?

No, “bad spark plugs do not cause white smoke.”

If the spark plugs are not working well, the engine will run roughly, and the unburned fuel will cause black smoke rather than white or grey. A coolant leak causes white smoke from a crack in the cylinder head, engine block, or blown head gasket.

How much white smoke from exhaust is normal?

A thin vapor, more like steam instead of smoke, is normal. This can result from condensation that collects in the exhaust pipe. It is common during winters because exhaust gases are hot, and when they mix with the cold environment, they cause vapor-like smoke. This thin smoke dissipates within a minute or just a few seconds. If this is the case, then it is normal.

Conclusion

The smooth functioning of the engine and its components is essential. If you notice any sign that can hint at an issue, it is better to check it, just like white smoke from exhaust when accelerating means a coolant leak. Similarly, steam or vapor from the exhaust can be caused by condensation. Therefore, it is crucial to keep checking and aware of small signs to prevent significant issues.