Car Smoking from Under the Hood? Here’s What to Do 

With over 30,000 parts that have to work together inside of a car to make it run properly, it’s no surprise that things go wrong all the time. There are hundreds of different ways your car can break down that range from minor inconveniences to deadly serious problems. Of all of these ways a car can go wrong, few are more frightening than when your car is smoking from under the hood.

Everyone knows that smoke is a bad sign. No matter what’s causing smoke to appear under the hood of your car, it’s not a good thing. But there are several reasons why this could happen, and several ways to deal with it.

 What Causes Smoke Under the Hood of My Car? 

Figuring out what caused the car to start smoking is a secondary concern when it happens. The first thing you want to do anytime you see smoke from under the hood of your car is to pull over right away as soon as it is safe to do so. You need to get out of traffic and get out of the car as soon as possible.

Although there are reasons why your exhaust pipe may have smoke coming from it, including smoke of different colors, from under your hood it’s another matter altogether. Smoke from your exhaust is not all that uncommon and can be dealt with in a timely manner.

• Motor oil. The most common cause for smoke coming from under the hood of your car is a motor oil leak or spill. If you recently changed your oil or topped it up and now your car is smoking, then you could make a reasonable assumption that this is the cause.

If your oil has not been changed or topped up recently and there is smoke coming from under the hood, oil still could be the culprit. It’s possible that you have a gasket or a seal that is broken and now oil has leaked out onto your hot engine.

Your engine works at extremely high temperatures and is meant to have oil inside of it, not outside of it. So, it’s possible that oil on the inside is now burning and causing the smoke that you see.

• Other fluids. Just like motor oil, the other fluids that run through your car could also potentially spring a leak. Anything from coolant to transmission fluid, to power steering fluid or window washing fluid has a chance to leak.

Depending on the nature of the leak, all it has to do is get on to a hot part of your engine to begin to burn. Regardless of what kind of fluid it is, having a leak is going to be bad for your car and causing smoke is extremely dangerous.

• Wiring problems. Your electrical system could start overheating and cause smoke from under the hood of your car. When this happens, you’re going to notice a distinctive, pungent, burning smell. 

The smell is caused by both the wire casing and the copper wires themselves burning. It’s possible that the alternator will be burning out, which is also noticeable in terms of smoke and smell. 

• Inlet manifold. This is what supplies the fuel and air to the cylinders in your engine. When it gets blocked, then the mixture is thrown off. The result is that your engine can start burning your fuel and air mixture inconsistently which can lead to smoke.

• Timing problems. In order for your engine to function properly, it needs to have everything happened at the exact right time. If the timing of your ignition system is off, then you may end up burning a rich fuel mixture, which is to say more fuel is being injected than it’s supposed to.

Rich fuel mixtures create black smoke. Often this will simply come out of the exhaust, but it can be forced out of your engine under the hood as well, especially if there are any leaks in the gaskets and seals.

What Do Different Colours of Smoke Mean Coming from My Engine?

 Not all smoke looks exactly the same coming from your car. Depending on the colour, you can have a few different things to be worried about.

• White smoke. If you’re seeing white smoke coming from under the hood of your car then you may have a few causes to look into. Coolant in the combustion chamber is one of the more common ones that can be caused by a crack in your engine block or cylinder head, or a bad head gasket. 

Typically, you’ll notice a sweet smell of coolant is the culprit here. Not only will you have the smoke problem to deal with, but your engine is at risk of overheating as well when this happens.

If, instead of a sweet smell, you can smell fuel burning, then you have a different problem here. Something has caused a leak in your fuel system and now gasoline is burning somewhere under the hood of your car. 

This is extremely dangerous and needs to be addressed as soon as possible. As you know, gasoline is highly combustible. The chance that this can change from smoke to fire is very high. The risk of explosion is also present. 

If you see smoke and smell gasoline, you need to get safely to the side of the road and away from your car as soon as possible. Once you are safely away from the car, then call for emergency help. Don’t try to lift the hood and inspect the problem yourself.

• Black smoke. This one is more likely to be caused by excessive fuel burning. However, excessive fuel burning usually results in black smoke coming out of the exhaust of your car rather than from under the hood.

A problem with your carburetor can also cause black smoke if you have an older car. Even a clogged air filter can cause black smoke to come from your engine. 

If the problem is with a bad fuel injector or a fuel pressure regulator, you need to get to a mechanic quickly to have the issue addressed. If the fuel issue in your engine is causing fuel to leak near the engine itself, this is what can escalate from smoke to fire.

• Blue Smoke. Typically, you will see this coming from the exhaust rather than from under the hood. However, blue smoke, which sometimes can appear almost as dark as black smoke, is a sign of burning oil. It may be dark grey as well, so it can be hard to distinguish between the two.

Usually, this kind of smoke is the result of oil that has leaked into the combustion chamber. This can be the result of a crack somewhere in your engine blocks, faulty gaskets, worn piston rings and valve seals, and even an intake exhaust manifold gasket leak.

When you have oil in the combustion chamber, it can lead to not just smoke but your engine overheating as well as engine misfires and damage to your spark plugs. Your engine will fail if you allow this to go on for too long.

What to Do When You See Your Car Smoking Under the Hood

When smoke starts coming from under your vehicle, you need to address it right away. At the very least, this is going to obscure your vision and potentially lead to accidents. At worst, you can have a total vehicle loss due to fire.

• Stop your car as soon as it is safe to do so.

• Turn on your hazard lights so other drivers are aware there is a problem and know to be cautious around your vehicle.

• Put your vehicle in park and use the parking brake, as well. Turn the engine off so that it will reduce the overall heat of the vehicle and slow any potential damage.

• Get away from your car to a safe distance as soon as you can. You should get at least 100 feet away from the vehicle. An engine fire can get out of hand in just minutes.

• If you think the situation merits it, call Emergency Services right away. If the engine is actively on fire, or the smoke is building and getting worse, you don’t want to try to handle this on your own.

• If the situation is not building to a fire but is actually diminishing since you pulled over, you will probably need to call a tow truck. However, keep an eye on the situation. The smoke gets worse, or a fire starts, emergency services will be needed.

• Don’t go back into the car. Engine fires can be unpredictable. Until you know it’s safe, you need to keep your distance.

 The Bottom Line

There’s never a situation when smoke leads to anything good. The best way to prevent situations where your engine will start smoking is to make sure you’re keeping up to date on maintenance like changing your oil, oil filters, and air filters on a regular basis. If the situation does arise when your engine is smoking, don’t try to handle it on your own, leave it to professionals and stay safe.