Smoke Coming From Exhaust—Here’s What Could Be Wrong

Do you need to know what could be wrong with your vehicle if you see white or black smoke coming from the exhaust? Well, we have researched what the problem could be and have answers for you.

If you have thick white smoke coming from your exhaust, it may mean that coolant is getting into your combustion chamber. This can be caused by a cracked cylinder head or a blown head gasket.

If you have black smoke coming from your exhaust, it is likely a sign that the engine is burning too much fuel. This can mean an issue with your air filter, fuel injector, or EGR valve if you drive a diesel.

In this article, we will discuss what could be wrong if you see white or black smoke coming from your exhaust and what you should do about it. It can be important to fix small problems on your vehicle before they turn into big ones. We will then explore some related questions. Keep reading to learn more.

Smoke coming out of the exhaust of a car, Smoke Coming From Exhaust—Here's What Could Be Wrong

White Smoke Coming From Exhaust

When you have thick white smoke coming from your exhaust, it likely means that coolant is getting into your combustion chamber. Check your coolant levels; if it is low, then you probably have a leak. The leak can be in several places.

It could originate from a cracked cylinder head or a blown head gasket. It could also be from a cracked seal. A blown head gasket can cost up to $2,000 to repair, and a  cracked cylinder head costs about $400 to repair.

A cracked seal would be cheaper than a cracked cylinder if you could fix it with affordable epoxy. Whichever issue it is, leaking coolant can cause further issues and should be fixed as soon as possible.

Black Smoke Coming From Exhaust

If it is black smoke you see coming from your exhaust, it could mean that your engine is burning too much fuel. In the combustion chamber, your engine takes in fuel and oxygen to create a small explosion. If there isn't enough oxygen for all the fuel to burn, then that could cause black smoke.

A clogged air filter can be the culprit by reducing airflow to the combustion chamber. It may also be a fuel injector issue. If your fuel injectors aren't releasing the right amount of fuel, that could be the problem. If you drive a diesel, it could also be an issue with the EGR valve.

Whatever the issue, it's a good idea to get it taken care of. If your engine is burning too much fuel, then gas efficiency can drop significantly. However, fixing these issues is much cheaper than fixing the issues related to white smoke, so consider yourself lucky.

Is White Smoke On Cold Start Normal?

When you cold start your vehicle, you may notice white smoke and be concerned. There is no need to be concerned if the white smoke is thin.

When you start your engine, condensation in the exhaust system turns to steam and results in what looks like thin white smoke. This is normal and is not a sign of a problem.

Can I Drive With White Smoke From The Exhaust?

A cars exhaust excreting smoke

If you have white smoke coming from your exhaust, like discussed before, it is a sign of coolant getting into your engine's combustion chamber. Remedy this issue if you don't want to cause a cascade of further vehicle issues that can get expensive fast.

If you do drive with coolant leaking, then your vehicle only has about one month before you can expect your engine to fail. So be sure to repair the issue as soon as possible.

How Do I Fix White Smoke From Exhaust?

Auto Chimps has information on what may be causing white smoke and how to fix it --let's delve into it!

First, if you want to fix white smoke coming from your exhaust, you have to identify whether it is a blown head gasket, cracked cylinder head, or a cracked seal. Once you know what part is damaged, you need to find whether you need to repair or replace the part.

Blown Head Gasket

If it is a blown head gasket, there is something you may be able to do yourself. If the gasket has only recently blown and isn't too damaged, you might be able to repair it yourself with a head gasket repair treatment.

Repairing The Head Gasket

You can find this product here on Amazon.

A product like this will repair a blown gasket that isn't too far gone. This can quickly remedy your white smoke issue.

If the gasket is has been blown for a little while and is too damaged to repair with a head gasket sealant, then you will have to replace your head gasket.

Replacing The Head Gasket

Replacing a head gasket is not a job you can do yourself at home. It is a very difficult job that takes a long time and many specialty tools. Unless you are a trained mechanic, we recommend leaving this job to a professional.

If you would still like to watch a video on how it is done, Humble Mechanic has a great Youtube video on the process:

Cracked Cylinder Head

There are two methods to repairing a cracked cylinder head. There are the pinning method and the welding method. We will look into both of these methods.

Repairing A Cracked Cylinder Head

If you are repairing a cracked cylinder head with a small crack, you may be able to utilize the pinning method.

You want to drill two small holes just big enough for the metal pins on the edges of the crack to prevent it from spreading. Then add pins along the crack so that the pins overlap slightly. Once this is done, go over the pins with an air hammer to seal the crack.

If you do this right, it can be very effective at sealing a cracked cylinder head.

Another method involves welding. If the cylinder head is made of cast iron, then you will need to do what is called a furnace weld. This is a difficult method to learn to do properly, but you can do it with practice.

For a furnace weld, you need to heat the cylinder head to 1,300 degrees Fahrenheit before welding. This helps to reduce stress in the metal and prevent cracking.

If the cylinder head is made of aluminum, you will have to do what is called a TIG weld. A TIG weld is a type often used on aluminum that uses gasses to keep oxygen away since aluminum forms an oxide layer while welding, which can ruin the weld.

Whether a weld is needed or you can use the pinning method, if you don't have experience, you may want to hire professionals for the job just to make sure it's done right. An improper pinning job or weld can fail soon after repair.

Replacing A Cracked Cylinder Head

If a crack is too big to repair of the cylinder head is just too warped, it may mean that you need to replace it. Replacing a cylinder head is a tricky job best left to professionals. You can expect it to cost about $200-$300 in parts and around $100-$200 in labor at a mechanic.

If you are driving an older vehicle, it can cost more for someone to hunt down a matching cylinder head since they can be hard to find, which is why many people opt to repair a cracked cylinder head until they absolutely can't anymore.

Cracked Seal

If it is a cracked seal is causing coolant to leak into the combustion chamber, you might be able to use an epoxy sealer. If applied liberally, an epoxy sealer can last for many months to years.

You can find this product here on Amazon.

The product will reseal a cracked seal with a special super strong epoxy. This can be a cheap and fairly effective method of sealing a cracked seal.

Can You Still Drive A Car With A Blown Head Gasket?

A blown cylinder head gasket photographed up close

You should not drive a car with a blown head gasket. With the head gasket blown, coolant can leak into the cylinders, creating further vehicle issues. Driving with a blown head gasket gives your vehicle about a month's lifespan before you can expect engine failure.

It is important to fix the blown head gasket before further problems develop.

Is It Worth Fixing A Blown Head Gasket?

It is worth fixing a blown head gasket because if left unrepaired, a blown head gasket can damage your whole engine. If you drive with a blown head gasket, you can expect your vehicle to last only one month. So be sure to get it fixed as soon as possible.

A blown head gasket costs between $1,000 and $2,000 to repair, so unless your vehicle is worth less than $1,000 , you should repair a blown head gasket.

Cash Cars Buyer talks a little about the price of fixing a blown head gasket and how in most cases, it is cheaper to repair a blown head gasket over getting a new car.

Final Thoughts

We learned several things could cause your exhaust to have white or black smoke. Some of these issues can be fixed with a simple product, but take your vehicle to a mechanic if you make a repair and still see white or black smoke.

Also, if your vehicle needs a repair you don't know how to do, see a trained mechanic. Don't attempt repairs that you don't feel comfortable doing. If you do, you may do more damage and make it more expensive to repair. 

We hope you enjoyed this article. If you would like to learn more, check out these other posts:

Clogged Catalytic Converter – How To Tell And What To Do?

Why Is My Car Burning Oil and What To Do About it?

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