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White Smoke From Your Engine: What You Need to Know

How Long Does It Take For A Car To Cool Down

When you’re driving down the road with your family in tow, the last thing you want to see is some white smoke from your engine or blowing out the exhaust pipe. Smoke is never a good sign and you don’t need to know a lot about cars to know that something bad is happening when that white smoke starts puffing out. The question you’ll be wondering next is what’s happening and what you can do about it. We’ll explain exactly what’s causing that white smoke from your engine and how you can deal with it.

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What Is the White Smoke From Your Engine?


Under normal circumstances, a combustion engine should produce water vapor and carbon dioxide as exhaust. The catalytic converter inside your exhaust is there to filter out most of the toxic by-product that causes pollution and leave your exhaust relatively clean. When you’re driving in traffic, this is why a car that seems to be “burning” a weird kind of fuel is noticeable. Most cars don’t belch noticeable smoke, only a small bit of exhaust. So, when your car is producing a distinct and thick cloud of white smoke, something has gone wrong.


When you see white smoke, you may have some kind of contamination in your combustion reaction. You’re supposed to be burning fuel and air to power your vehicle, but sometimes other things can leak into the combustion chamber. For instance, if you notice smoke with a tinge of blue to it, you likely have an oil leak and the burning oil is producing blue smoke. Black smoke is fairly common as well and can have several causes from too much fuel being burned because of a faulty mass airflow sensor to clogged air filters. White smoke, however, has different causes.


  • Thin white vapor: Some people may mistake the normal vapor of exhaust for smoke, especially if it’s a cold day. The steam in the exhaust will be especially robust in colder weather and this can give the impression of smoke. This is true especially in an enclosed space like a garage which may amplify the effect. However, if it is a cooler day and the smoke appears thin and disappears fairly quickly, then you likely just have the normal exhaust vapor coming from your car and there’s nothing to worry about.
  • Sweet-smelling smoke: If the smoke is thick and white and has a slight sweetness to the smell of it then it's very likely you have a coolant leak. Antifreeze is known to be sweet and in fact you need to keep it away from animals like cats because they will be attracted to the smell and try to drink it. When it mixes with your fuel and burns, then you’ll definitely have a thicker than normal exhaust and a discernible odor. It likely won’t be incredibly strong, but it will be noticeable. There are a number of reasons that can lead to a coolant leak, which we’ll get into shortly to help explain why this might be happening and what you can do about it.
  • Regular white smoke: If there is no smell to the smoke but it still billows out white there may have been an accumulation of condensation in your exhaust. This will happen in the morning when you first start your car, especially if the night was cooler and warmed up. Just as condensation can form as dew on the grass it can form in your exhaust system. This should burn off quickly as your car heats up. If it’s persisting after that, then there is another problem likely related to a coolant leak.

Why Is White Smoke Coming From My Engine?


Knowing that coolant is leaking into your fuel supply is helpful in diagnosing the cause of the smoke coming from your exhaust but that doesn’t explain how it got there in the first place. There are a few reasons to account for how coolant found its way into your engine.


  • Blown Gasket Head: When you have a blown gasket head, you’ll have fuel leaking in the engine compartment. A bad leak may drip right out below the engine manifold and be visible to you but if it happens, you'll get the white smoke in your exhaust as the fuel mixes with the coolant. This is also going to lead to an overheating engine fairly quickly and can escalate from white smoke in your exhaust to white smoke under your hood. A blown gasket head can be a costly repair but not getting it fixed as soon as possible can lead to extensive damage to your vehicle. This has the potential to lead to serious problems like a stalled engine, fires, and catastrophic engine failure. For this reason, you absolutely need to have this problem addressed as soon as you possibly can.
  • Damaged Cylinder Head: If you have a cracked cylinder head then the coolant will leak into the cylinder or even the combustion chamber and mix with the fuel during the combustion reaction in much the same way that a blown gasket will cause a coolant leak.In both of these cases the coolant levels in your vehicle will give you some indication of what you’re dealing with, just remember to only check coolant levels in a cold engine. You never want to remove any caps or seals when your engine is hot as you risk coolant boiling up and burning you.
  • Faulty Fuel Injector: The fuel injector’s job is to add the precise amount of fuel into the fuel/oxygen mix to ensure the greatest efficiency of your engine during its operation. Modern engines are incredibly well calibrated and anything that alters this precision can have a stark effect on how your car performs and the costs associated with running it. If your fuel injector is not working correctly you can be getting a rich fuel mix, which is to say too much fuel and not enough air. That excess fuel won’t burn correctly in the engine and will come out the exhaust as white to grey smoke.
  • Injector Pump Timing in Diesel Engines: Much like the faulty fuel injector in a standard engine, if you’re running on diesel and your injector pump timing is misaligned, you'll be getting too rich of a fuel mix. That will result in you losing the excess in the form of smoke out of your exhaust
  • Leaking Valves/Seals: If your piston rings or valve seals are bad then they’re going to be letting oil leak in which can burn in your engine. As we said earlier, oil leaks tend to mix and burn blue but, if the leak is not substantial it may be hard to tell the blue coloration and it may appear white at first.
  • Clogged Fuel Filter: Though rarer than these other causes, a clogged fuel filter can also cause your car to start belching white smoke. The smoke would not be the only symptom of this problem though and you’d likely have issues with the vehicle struggling and losing power as well.


What Will it Cost to Fix the White Smoke Problem?


As we’ve seen, there are a lot of potential reasons for your car to be producing white smoke in the first place and that means here are just as many potential repair bills to go along with it. Let’s take a look at some of what we’ve covered, and those associated costs.


  • Fuel Filter Repair: If this is the root of the problem for you, then you're looking at a repair cost of $50 to $165depending on where you live and the make and model of your car. Overall, this is one of the least expensive repairs for an issue with white smoke that you’ll face.
  • A cracked cylinder head, like most of these repairs, may have a range of causes and that means the price varies to reflect how it’s handled. For that reason, you could be looking at a repair bill from $500 to $1000.
  • Leaking valve/seal: Because this covers a range of potential problems. Something like the positive crankcase ventilation valve needs to be replaced, you could be as low as $60 to $100. However, depending on the nature of the leak you could face a repair bill from $150 to as high as $1,200.
  • A broken fuel injector is a much more in-depth repair and the price definitely reflects that. If this is the source of your problem, you may have to pay anywhere from $1,100 to $1,500.
  • A fuel injector pump like we described causing a problem for diesel engines will also be a costly repair if it’s the source of your white smoke. Having this part repaired or replaced carries an average cost of $1,400 to as high as $2,000.
  • A blown gasket head can be an extremely costly problem to fix, and the range is also hard to narrow down precisely. You could be as low as $1,000 and potentially as high as $2,500. We detail everything you need to know about what can cause a blown gasket head and how to repair it over here.


As you can see, there’s a really dramatic range of costs and causes for a white smoke problem with your car. It’s precisely because there are so many causes and symptoms that we can’t narrow down a cost for you much more precisely than we have, unfortunately. But this also means that when you see white smoke coming from your exhaust you need to get it attended to as soon as possible because the issue could be very serious.


Can I Drive With White Smoke From My Engine?


Generally speaking, your car will probably still function when you see white smoke coming from the exhaust, but it is a good warning sign that you need to act quickly. This is even more clear when the smoke is not just being released from your exhaust but from under the hood itself. While a minor coolant or oil leak could be a relatively simple repair, this can be the first indication of one of the much bigger problems we mentioned.


A blown head gasket left untreated can lead to a catastrophic engine failure if it’s not addressed before it’s too late. Anything from a snapped crankshaft to a complete engine repair or replacement may be necessary.


The long and short of it is that when you see white smoke and it’s not just normal exhaust vapor, you need to get your vehicle checked as soon as you can. The repair bill may be steep but not getting it repaired could lead to even more serious damage and repair costs as well as a dangerous situation that ranges from your engine dying to overheating and even catching fire if there is a coolant or oil leak. That can be a serious danger to you and other drivers on the road. You need to take the presence of white smoke seriously.


Is it Worth Fixing The White Smoke From Your Engine?


Any problem is definitely worth fixing if your car is still in relatively good condition and it’s still something you want to put effort into repairing. If you have a much older vehicle that has other problems, and the cause of your smoke is more serious like a blown head gasket, then this might be something worth thinking about to weigh the pros and the cons. An older vehicle billowing white smoke likely has other problems you need to be aware of as well. Depending on the overall value of the vehicle, a repair bill of $2,500 or more might be counterproductive for you.


The best thing you can do is check out the value of your car based on its make, model, and year to see what it’s actually worth right now. You can look up your car’s value on a trusted site like Kelley Blue Book and that will help you determine whether investing a serious amount of money in repairs is even worth it.


If the issue is too serious, you may want to consider just selling your car as it for the parts or, if it’s gone too far gone, even as a junker. It really does depend on the situation and your own personal needs, as well as your attachment to your vehicle.


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