White Smoke From Exhaust - Main Causes & Fixes [Guide]

What color should it be?

When the car’s engine is running properly, you shouldn’t see anything coming out of the exhaust.

However, if there is white smoke coming out of the exhaust, there may be something you need to pay attention to.

What causes white exhaust smoke? Possible causes include:

  • Condensation in the Exhaust
  • Cracked Cylinder Head
  • Injector Pump Time Off (Diesel Only)
  • Bad Fuel Injector
  • Oil in the Combustion Chamber
  • Cracked Engine Block

While the former is completely harmless, the rest can be disastrous if neglected.

Luckily, in this quick guide, we’ll cover each of the above causes in detail, including how to fix them.

Let’s get started!

White Smoke Out of the Exhaust? 6 Possible Causes And How To Fix It

Cause #1 – Condensation In Exhaust

If you wake up one morning, start your car, and it starts to emit white smoke from the exhaust, it’s likely due to condensation.

When warm/hot exhaust gases meet cold outside air, the result is steam. While it may look alarming, it is a perfectly normal reaction. Say hello to science in action – impressed?

How to fix

Depending on how cold it is outside, driving your car for a short time should be enough to reduce the white exhaust fumes.

Unfortunately, this is the only cause of white exhaust smoke on the list which is resolved with patience. The rest can cause serious engine problems if left alone.

Cause #2 – Cracked Cylinder Head

car cylinder head

Oof, we probably shouldn’t have put this cause of white smoke so close to the last one, because when a cylinder head cracks, it’s no laughing matter.

As you might expect, the cylinder head is located on top of the cylinder. It houses both the intake valve, and the exhaust valve, which adds the air/fuel mixture to the combustion chamber, and vents what is generated outside.

They are usually made of cast iron or aluminum, the latter of which is preferred because it conducts heat more quickly, as well as being lighter.

No matter what your material is, if it ends up in cracks, you have a real problem on your hands. One thing that may happen from a cracked cylinder head is that exhaust gases can seep back into the cylinder head.

When this happens, white smoke is generated, which will come out of the exhaust.

The most common cause of a cracked cylinder head is engine overheating, which can have a variety of causes. See this guide to take an in-depth look at why your car might be overheating.

How to fix

Ready for another bad news? In most cases, the only option for permanently treating a cracked cylinder head is to replace it.

While it’s not a difficult job, it does take a little time. Add the cost of parts, and a cracked cylinder head replacement will cost between $500-$1000 depending on whether it’s aluminum or cast iron.

Another option you have is to try a store-bought head gasket repair product. See this guide for some of the best on the market.

Cause #3 – When the Injector Pump Dies (Diesel Only)

diesel injection pump timing

If your engine runs on diesel, the white smoke coming from your exhaust is likely from an injector pump timing issue.

The pump itself is in charge of supplying the cylinders with diesel. If not delivered in a timely manner, it can cause excess diesel fuel, which can cause thick white smoke to come out of the exhaust.

Other signs of an injector pump failure include:

  • Poor damn
  • Reduced performance
  • Poor fuel economy
  • Rugged performance
  • Trouble starting
  • RPM limit reduced
  • Throttle jump

Just because “total failure” isn’t on your list of symptoms, doesn’t mean you should ignore it. Doing so can damage the entire system, which can eventually cause the machine to not operate at all.

How to fix

Unfortunately, solving this problem is not something we recommend trying at home, as it requires tools and knowledge that only certified technologists have.

If it is determined that the time the injector pump is off, it may be as easy as reprogramming the ECM. If that doesn’t solve the problem, you may have to replace the pump completely. Another possibility is that you will need to replace the camshaft, which can cost anywhere from $1,500-$3,000.

What are the main causes of injector pump failure? Contaminants in diesel fuel. One way to extend the life of the injector pump is to regularly replace the diesel fuel filter, and only fill your tank at Top level station.

Cause #4 – Bad Fuel Injectors

bad fuel injector

The fuel injector is basically a spray nozzle that delivers fuel to the combustion chamber. It does not control when or how much fuel is delivered, it only acts to limit or permit its passage. This system is very precise, meaning that even the smallest variation can throw it off balance.

This is what happens when the fuel injectors fail, which, as you may have guessed, can cause your car to emit white smoke from the exhaust.

Other things you might notice that suggest you have a faulty fuel injector, include:

  • Throttle jump
  • Reduced performance
  • Poor fuel economy
  • Poor damn
  • Rugged performance
  • RPM limit reduced
  • Trouble starting

With this list of problems, ignoring a bad fuel injector will quickly become unbearable. Not only that, but it can throw the entire system out of balance and lead to expensive engine repairs.

Why do fuel injectors fail? Contaminants in the fuel, mostly. One way to extend fuel injector life is to replace the fuel filter regularly every 2 years or so, and only fill it at Top level station.

How to fix

Once a fuel injector fails, its life has expired – meaning that repair cannot be done, so you will need to replace it. However, you should always replace the entire set of fuel injectors rather than just one. Otherwise, the engine will not run evenly.

Luckily, it’s not a complicated process if you have a little time one afternoon. see this video for a step-by-step guide on how to replace a fuel injector.

It’s also possible that your fuel injectors are clogged, rendering them effectively useless. The good news is there is existing products that can help clean it.

Cause #5 – Oil in the Combustion Chamber

broken piston

The only things that must be in the combustion chamber are air and fuel. If the oil ends up there too, it will ignite with this mixture, producing a thick cloud of white smoke that oozes out of the exhaust. Other signs include increased oil consumption and engine stalling.

Why is oil in the combustion chamber? It likely means the piston rings or valve seals are leaking, allowing oil to flow in.

The reason why this is worrying is if there is oil where it shouldn’t be, it means it’s not where it should be. When various components of your engine don’t receive enough motor oil, it can cause them to fail.

In most cases, you shouldn’t have a problem with this until after the 100,000 mile mark. One way to help preserve it is to switch to high mileage motor oil once you have.

How to fix

Unfortunately, replacing piston rings is very expensive, usually costing between $1,800-$3,500 for parts and labor. Parts only run around $75-$200, making it a very time-consuming job. Replacing valve seals costs a little less, but can still cost up to $2,000.

Can you replace it? valve seal or piston ring alone?

If you are comfortable disassembling the engine, then you can save a lot of money. However, whether you are skilled enough or not to do so is another story.

Cause #6 – Cracked Engine Block

cracked engine block

And then there’s this one – the cracked engine block. While ignoring the previous causes may eventually lead to the worst case scenario, knowing that you have a gap in your engine block is that scenario.

The engine block is the main structure on which every other component is built.

Fortunately, most engine blocks are made of cast iron or aluminum alloy. Meaning they are not only durable but also great for transferring heat away from the engine. However, if any of the engine components does not function properly, the block can overheat, weakening it.

Some common symptoms that a block may be overheating include:

  • White smoke coming out of the exhaust
  • Poor engine performance
  • Puddles of liquid under your car
  • Color changing anti-freeze
  • Freezing coolant in radiator

The reason a cracked engine block can cause white smoke to come out of your exhaust is because oil is leaking into the combustion chamber. When this happens, it mixes with the air/fuel mixture and ignites. The white smoke that is created will then be sucked out and out through the exhaust.

Ignoring a cracked engine block is not an option. The engine cannot maintain proper compression if it leaks out, so performance will drop significantly. Not only that, the longer it is left on, the more likely it is to cause further damage.

How to fix

There are three possible methods for repairing a cracked engine block, re-welding, sewing cold metal, or using cold metal fillings. Each one works as it sounds, either by welding the crack, sewing it closed, or patching it.

Regardless of where you have professional performance – it doesn’t come cheap. In the end, don’t be surprised if you end up spending between $2,500-$4,000 on a temporary fix.

We Hope It’s Due to Condensation

white smoke coming out of exhaust pipe

But if not, don’t mess around, because it will end up costing you a lot of money if left untreated.

One way to make sure your car lasts as long as possible is to take good care of it. See our previous article for 15 essential car care tips to will give you a fighting chance.

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