White Smoke Coming from Exhaust: Causes & What to Do About It

Car emissions can at times appear in various colors, such as white smoke, black smoke, gray smoke, or blue smoke.

In most cases, the exhaust from your tailpipe should be clear, and differently colored smoke usually suggests a problem.

Exhaust pipe smoke can be due to a number of different causes, and can usually be dealt with by applying the right techniques. It may indicate faults in the vehicle that should be handled quickly to avoid any further damage from taking place.

In this article, we’ll discuss white exhaust smoke, its causes, and what to do if you notice it coming from your vehicle.

Black car with white smoke coming out from the rear exhaust

In most cases, the trouble causing these exhaust issues in your car can be managed at home without having to resort to a mechanic for car repair help.

In certain circumstances, though, the skill or equipment needed to deal with this problem will be too advanced, so a visit to a garage will be in order.

Always keep in mind that it’s best for drivers to maintain and address issues with their vehicles as soon as possible – and smoke from the exhaust is certainly no different!

Skill Level: Moderate

Time to Complete: 30–60 minutes

Tools Needed:

  • Engine coolant
  • Engine oil
  • Transmission fluid
  • Replacement intake manifold gasket
  • Replacement head gasket
  • Replacement cylinder head

Should You Be Worried?

So, you notice white smoke coming out of the exhaust when starting the car, or in the middle of a ride. Should you be worried about this?

This depends on what’s causing the white smoke to be coming out from your exhaust in the first place.

First things first, it’s necessary to identify the exact type of smoke your car is producing.

In some cases, the smoke may point to a condition that needs to be dealt with straight way, while in other situations, the smoke may be no cause for alarm.

It’s not just your vehicle you need to be worried about, either. A vehicle producing a large amount of smoke may also be an environmental concern, as fumes can potentially be a dangerous cause of pollution and be very harmful to the environment.

So, the takeaway from this section is that drivers should seek to resolve the issue of white smoke coming from the exhaust sooner rather than later.

What Are the Causes of White Exhaust Smoke?

Let’s take a look at some of the most common reasons why your exhaust may be emitting white smoke:

Condensation

In cold or humid conditions, the source of the smoke may be condensation that builds up in the exhaust system.

When it’s still cold, water will collect in the exhaust system. This will then be released as steam when the engine is turned on. It will be thin white smoke, similar to vapor. As the engine warms up, it will dissipate.

The lower the temperature is, or the higher the level of humidity, the denser the exhaust fumes noticed will be.

However, if it’s thick white and cloudy smoke, the issue is probably more serious than simply condensation.

Faulty Fuel Injection Pump Failure

In diesel cars, the problem may be caused by a failure with the fuel injection pump timing.

The injector pump is needed for pumping fuel into the cylinders. Timing is important because the fuel must be injected in the middle of the cylinder’s compression stroke. This helps with fuel efficiency and to prevent an overflow.

This failure may be caused by a faulty engine control unit. If this is the case, then the unit simply needs to be adjusted to correct the timing of the fuel pump injection.

Irregular fuel injection can cause white smoke to be emitted from the tailpipe.

Leaking Coolant

One of the main causes of white exhaust smoke is engine coolant leaking to different parts of the engine. White smoke will be released when even small amounts of coolant enter the combustion chamber.

If this is the cause, then the exhaust smoke may come with a sweet smell. There may also be a low level of coolant reserve. The coolant can affect the engine oil ans cause it to produce a frothy or milky consistency.

There are different factors that can cause engine coolant to leak:

Cylinder Head

The cylinder head closes in the top of the cylinders to form the combustion chamber. A coolant loss may be the result of a cracked cylinder head or warped cylinder head.

This can be brought on by other parts being incorrectly installed. It can also be caused when the contrasting metals of different parts have different expansion rates. However, the most common cause is from the engine overheating.

Cylinder Head Gasket Failures

The cylinder head gasket (or just head gasket) sits between the engine block and cylinder head to seal the cylinders and maximize compression.

Failure of the cylinder head gasket is another cause of a coolant leak.

If the gaskets are unable to seal properly, then coolant can be lost. It can also lead to leaking oil and a loss of compression. This can be noticed from a loss of power from the reduced compression in the cylinder.

Again, this failure is most likely to be due to overheating, and a faulty head gasket will – in turn – exacerbate this.

Intake Manifold Gasket

The intake gasket seals the intake manifold against the cylinder heads to create a vacuum. It’s also known as the inlet manifold gasket.

This gasket leaking is usually the most common cause of internal coolant leaks.

These leaks would most probably be caused because the engine is hot. However, they have limited use, so a failure could also be from general wear.

Engine Block

The engine block is the structure that houses the cylinders and other parts of the engine. If this is cracked, it can allow coolant to leak into the combustion and chambers, which can be dangerous.

A cracked engine block could be caused by structural damage to the engine or from overheating. This could be the result of a lack of coolant (low coolant levels) or a faulty water pump to distribute the coolant.

Transmission Fluid

If you notice that white smoke is produced while you’re accelerating, the issue could be with your transmission fluid. In these cases, the exhaust may smell of burned oil.

However, white smoke during acceleration could also be due to burning coolant, which usually points to a damaged cylinder head or gasket. When this happens, it might be a sweet odor.

Transmission fluid is used by vehicles with automatic transmission, for various transmission requirements. This can leak and burn, producing white smoke.

It may be caused by a hole in the transmission system – these could be in the gasket of the oil pan, the fluid lines, torque converter, transmission oil pan, or various seals.

Leaking Oil

Sometimes, engine oil can leak out of the piston rings or valve seals, and it can then flow into the internal combustion chamber and mix with the fuel. Together, gas and oil will cause emissions to turn white or even blue.

If the oil is not being used to lubricate the engine, it can be damaged in many different ways. For this reason, the problem should be resolved sooner rather than later.

It should be easy to identify an oil leak from the smell of the oil. It may also be possible to check for an oil leak by holding some paper over the exhaust while the engine is running: black spots on the paper would suggest that there is an oil leak.

White Smoke From Exhaust Pipe: How Can I Address the Situation?

Hopefully, you’ve now been able to identify the source of the white smoke coming out of your car’s exhaust (or know what to look for by now).

Now, let’s take a look at some of the possible solutions to fix the problem:

At the Garage

In cars with diesel engines, and if the issue is with the fuel injection, then this should be checked by a mechanic. The expertise required for this will be too difficult for most drivers to take on themselves, without the help of a professional.

Maybe you’re unable to identify the cause of white smoke, or maybe you can’t seem to resolve the issues all on your own, even though you know for a fact what’s causing it.

In these cases, you should always find a trusty mechanic to help you out.

However, if you are able to deal with the problem at home yourself without messing up and causing a more serious problem than the one you had to begin with, then you will likely save yourself some time and money doing it alone.

At Home

Follow these steps to start addressing the white smoke coming out of your car’s exhaust on your own at home:

Check the Coolant Levels

Checking engine coolant levels in the reservoir can determine if a coolant loss is causing the problem. Make sure the engine is off and cooled down before starting your inspection.

Looking under your car’s hood, the coolant reservoir is usually easy to locate.

You should be able to check the coolant levels by looking at the tank, as the container will be transparent. There will be markers on the reservoir to show the levels of coolant.

If the levels are low, then you should obtain the correct coolant fluid that’s best suited for your car, and fill to the indicated amount.

If you cannot find the reservoir or are unsure which coolant to use, check your car’s manual to learn about all those details.

If the levels are correct, then a cooling system pressure check may be necessary. Otherwise, the irregular exhaust may be a cause of something entirely different.

Check the Head Gasket

To try and find where the coolant is leaking from, you can start by checking the head gasket.

Check to see if the leak is caused by the head gasket by doing a leak down test. You can do this by pumping air into the cylinder and noticing if any air has leaked through the head gasket.

Note that this test may need to be carried out at a garage.

Check the Cylinder Head

The cylinder head is located at the top of the engine block. If it’s broken or damaged, it will need to be replaced. The cylinder head will need to be removed in order to check for leaks.

One way of doing this is to pour water over the valves of the cylinder head. Water that drips through the valves will suggest a leakage. If the cylinder head is leaky, it will need to be replaced.

Check the Intake Manifold Gasket

To inspect the intake manifold gasket, the intake manifold needs to be removed.

This is usually a task for a qualified mechanic, so please don’t try to do this all on your own if you’re not exactly experienced in this area, as you might end up causing a more serious problem than the one you had to begin with.

If there is rust in the gasket, then this will need to be cleaned. If the gasket is damaged, then it will need to be replaced.

Check the Transmission Fluid

If the level of transmission fluid in your vehicle is low, then you can add more.

Before you start, check first that you have the correct fluid. If you don’t know which is which, you can find this information in your manual.

It may also be necessary to replace the transmission vacuum modulator valve.

How Can I Prevent My Car Exhaust From Emitting White Smoke Again?

As the most likely cause of discolored emissions is leaking coolant, it’s a good idea to check your level of coolant regularly and make sure that all is good to go on that front first.

Coolant is also essential in keeping the engine from overheating. Since overheating can be the cause of many other problems in cars, it’s advisable to prevent this at all times.

It is also recommended to check the parts where leaks are most likely to occur.

As already mentioned, leaks can often be found in the intake manifold gasket, the head gasket, or the cylinder head. They appear as a result of engine wear, such as a lack of lubrication caused by insufficient amounts of engine oil.

Checking the levels and the quality of your engine oil on a regular basis is another safeguard against engine wear. This will also prevent the engine from overheating.

Last but not least, checking your levels and quality of transmission fluid on a regular basis is another way to prevent issues such as white exhaust smoke. As a general rule of thumb, this should be changed every 30,000 to 60,000 miles traveled.

Conclusion

As we’ve seen in this article, there are a variety of different reasons for white smoke to come out of your car, so pinpointing it on one cause is not always that obvious and easy.

Many of the checks that we can apply to our vehicles demand advanced equipment and knowledge.

However, even when we are not able to carry out the inspections ourselves, understanding the workings of our cars is still valuable.

Not only does this help us appreciate the machine we’re driving to and from our destinations every day, but we could also use this knowledge to avoid future difficulties as well.

And always remember this: if you’re seeing white smoke from your car’s tailpipe and can’t seem to solve the situation on your own, leave it to a mechanic ASAP!

Kyle Palmer

From childhood go karting and motocross, to collecting and obsessing over scalextric, matchbox and radio controlled cars, I've always had an obsession with cars. Learning through manuals, books, trial and error, and more knowledgeable family members, I've also enjoyed tinkering with the mechanics and electronics of any vehicles I've owned. Now, over 3 decades later, I've started this site as a place for me to share my knowledge, to teach others how to care for and maintain their vehicles themselves, at home, so they can get the most of their vehicles and save a pretty penny compared to always seeking out professional help.

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