A few days ago, a customer called our shop at 10 PM: “I can’t believe it! I’m on my way home, and I noticed some smoke coming out of the car. Why is my car smoking? What should I do?” 

Well, it is a complicated question for both novice and experienced drivers. There are many reasons for this, and some of them require prompt action. 

But don’t freak out yet, Drive Revolve got your back! In this handy guide, you will find the quickest way to pinpoint the real issue. Whether you are tearing your hair out roadside with a smoking engine or just doing some quick search at home, read until the end – this post can save your life!

Why Is My Car Smoking: Diagnose The Issues

As mentioned, smoke coming from engine can signify a lot of things. Some of the culprits include: 

  • Malfunctioning fuel valves 
  • Burnt electrical wires 
  • Problems with the cooling system
  • Leaky head gaskets 

What your car smoke is trying to tell you?

Of course, they are the most common, not the only possible causes. To find out the problems, ask yourself:

  • Where does the smoke come from? For example, you can see a cloud of smoke from under the hood or belching from the tailpipe.
  • What is the smoke’s color? Car smoke usually comes in white, black, blue, or grey. Each color signals a different issue. 
  • When does the smoke appear? So your car only emits a white puff of smoke after sitting overnight? Do you see some steam or vapor coming from the hood on rainy days? Or are you driving, and suddenly smoke begins to billow from the tailpipe? 
  • Is your car overheating? 

We simply don’t have enough time to go through this checklist in urgent situations. The quickest way is to determine where the smoke comes from and its color. 

White Smoke Coming From Car

White Engine Smoke 

car blowing white smoke
Sometimes you notice your car blowing white smoke but not overheating – Source: Cash Car Buyer

When your car’s engine emits white smoke, we are dealing with a coolant leak. A coolant leak frequently comes with an overheated engine and might be caused by the following factors: 

  • Damaged coolant or radiator hoses: You can observe the damage to the radiator’s hoses just by opening the bonnet. They may rupture, swell, and break over time. 

Expect the price of repairing a coolant leak to be about $100. If it’s a small leak that simply has to be sealed, it even costs less. Still, I’d recommend letting a professional mechanic do the job.

  • Faulty engine block: The engine blocks keep all the engine’s essential parts in place. If the temperature drops too low, the coolant can be frozen, pushing against the block’s walls. This results in small cracks. 

You can fix tiny cracks by yourself with an engine block sealer. When they are bigger, though, a trip to the auto repair shop is required. Technicians will have to re-weld some pieces of the block or use the cold-metal stitching technique. 

Be warned: The process is time-intensive and expensive, with potential costs ranging from $1,000 to $4,000. With some models, it’s best to purchase a new vehicle. 

White Exhaust Smoke

Do you notice white smoke from the tailpipe of your vehicle? If it vanishes quickly, it’s due to the accumulation of condensation. Stay calm – it’s no big deal! 

Nonetheless, if white smoke keeps coming out long after you start the car, the engine will likely burn coolant seeped into the combustion chamber. We have several scenarios:

  • Blown head gasket: The internal combustion process is sealed by the head gasket, preventing coolant and oil from mixing together. In most cases, an overheated engine will make it blow. The coolant then gets into the combustion chamber, evaporating into smoke. 

Take a look at the cap of your oil filler. When this happens, the oil will be mixed with water, and you can spot a light brown deposit. 

Tiny cracks can be fixed with some sealers. If the damage is more serious, you will need help from a professional. The cost of the repairs ranges from $600 to $1,000. 

  • Malfunctioning cylinder heads: The master cylinder heads can be found above the engine block. If overheated, they can become deformed, causing the engine to misfire. As the seal is broken, the coolant will leak out and be burned off as smoke. 
You can still drive with a broken cylinder head, but the problem will get worse over time – Source: enginereplacementofatlanta

Since the cylinder heads have to be perfectly aligned with the connecting components, replacing the cylinders altogether is usually more cost-effective than repairing the heads alone. The average cost falls between $2,100 and $3,700. 

Black Smoke Coming From Car

Black Engine Smoke 

When your engine emits black smoke, the engine is burning excessive fuel. But why does that happen? 

  • Problems with the fuel injectors: The fuel injector is the first thing that comes to my mind. This part transmits diesel or petrol into the engine as a high-pressure mist. Over time, as the seals begin wearing and tearing, fuel injectors leak.

Because the problem is not complicated, a mechanic can replace your injectors and seals at a reasonable cost of between $350 and $850.

  • A broken fuel pressure regulator: As its name implies, a fuel pressure regulator controls the pressure of the car’s fuel. Depending on each car model, you can find them inside or outside the fuel tank. 

Take your car to the nearby garage and let them determine whether you only need a new fuel pressure regulator or a fuel pump as well. 

  • Issues with the carburetor: Older car models combine fuel and air using a carburetor. When the part becomes dysfunctional, it sends excessive fuel or diesel to the engine. Thus, the engine lets out black smoke. 
  • Wrong ignition timing: For it to properly burn during the combustion cycle, fuel ignition must happen at the right time. If you have the wrong timing, the engine will use more fuel than it needs and, in the worst situation, emit thick black smoke. 

All the problems above are simple to fix without breaking the bank, but only when you notice them early. Running a car with malfunctions that allow fuel to escape onto the engine for an extended period can lead to the combustion of that fuel and total loss of the vehicle by fire, so don’t wait until you see black smoke. Check the car frequently and seek help from a mechanic as soon as you think your car is using more fuel than usual. 

“Why is my car smoking under the hood?” – Diagnose smoking & steaming under the hood of your car

 Black Exhaust Smoke

In fact, it’s fine if your car only gives off dark smoke from the exhaust when it’s just started. 

However, you should be concerned if the issue continues after running. The culprit is often a clogged air filter. It keeps dirt and debris from entering the vehicle’s engine. Over time, contaminants build up inside the air filter, making it unable to work correctly. 

If the debris makes its way into the combustion engine, it will be burnt off. What we see after are black clouds of smoke. 

Fortunately, this is not a complex issue and can be fixed right away by replacing your filter. Many of them cost around $15 to $25. Phew! 

Blue Or Grey Smoke Coming From Car

Blue Or Grey Smoke Coming From Exhaust
Blue and grey smoke is never a good sign – Source: hummelsautorepair

In rare cases, you can see blue or grey smoke from both the engine and exhaust pipe. It’s a tell-tale sign that your vehicle is burning oil. Let’s discover the reasons: 

  • Broken valve stem seals: In combustion engines, the valve stem seal provides lubrication to the valve, which helps maintain the appropriate mixture of air and fuel. When the parts start to get loose, the seal is lost, and oil can escape. 

Fixing the issue might be time-consuming and costly. This depends on whether or not you need to rebuild the engine. 

  • Broken piston rings: What if the smoke is not entirely grey but also slightly blue? Without a doubt, your piston rings are damaged. Located in cylinders, these parts can leak oil if their seals are broken. 

Since the fault rarely occurs, getting it fixed requires the help of a professional.

  • Failed PCV valve: Also known as a Positive Crankcase Ventilation valve, this part works to vent unburned fuel or exhaust gas from the engine block. 

When the PCV valve gets stuck, the engine’s air, oil, and other gases will be mixed together. The burning of this substance produces a bluish smoke. 

Worry not – solving the problem only costs around $76 – $92. The only problem is that you can’t merely fix it; rather, a replacement is required. 

If there is an oil leak in the combustion chamber, the car may have a rough or unsteady idle, misfire, or foul the spark plugs. The engine will suffer from an increasing amount of strain as the condition gets worse. Ultimately, this leads to a loss of power, intense shaking, and, worst case, a complete engine breakdown. 

Keep Calm And Drive Safely! 

“Why is my car smoking?” Next time, this question won’t be trouble for you anymore! In this article, you’ve found out the potential reasons for smoke coming from engine and exhaust, what the smoke color signals, and what to do in each scenario. 

A smoking car is at risk of being stopped by law enforcement. In some states, the driver may receive a fee and even has the vehicle impounded. Diagnosing and fixing your vehicle as soon as possible can save you a lot of money and valuable time, so head to our Fun Autopart section for advice if you sense any problem early on! 

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