Grey smoke from exhaust when accelerating

When everything is working the way it should, there should be no visible emissions coming from the exhaust pipe of your car. If you see smoke, it's likely a sign that something in the engine is wrong. But did you know that the color of the smoke can point to the cause of the problem? At Nate Wade Subaru, we want to help you learn more about how best to take care of your vehicle. With that in mind, here are the four most common colors of visible tailpipe emissions, as well as a rating of how dangerous they are for your engine.

If you suddenly notice that something looking like white smoke is coming from the tailpipe of your car, you may not need to worry just yet. As long as it's relatively thin and goes away within a few minutes of starting your vehicle, chances are it's not smoke at all, but water vapor. When your car sits outside, especially overnight, condensation can build up inside of the exhaust system. Starting your car will warm that condensation, turning it into steam. As the exhaust system warms up, the condensation will disappear, and the white steam along with it.

If your exhaust pipe is emitting black smoke, it's likely because the fuel/air mixture is too rich. In order to combust properly, your engine needs a precise mixture of fuel and air. The mixture is "rich" when it has too much fuel or too little air. If this is the case, you'll probably need to take your Subaru to an authorized service center. There are a number of things that could cause a rich fuel/air ratio, including clogged fuel injectors, a dirty engine air filter, or the fuel-pressure regulator. These problems likely won't put your engine in immediate danger, but they certainly can take a toll.

Unlike the white condensation that's generally totally benign, plumes of white smoke billowing from the tailpipe are a sure sign of trouble. It usually means that coolant is being burned in the engine, which means that something is drastically wrong. The most common cause of this is a blown head gasket, which can quickly lead to an overheating engine. But it could also be due to a cracked cylinder or engine block, making it necessary to replace the engine entirely. If you see this kind of smoke, pull over and turn off the engine as soon as you can, and then call for a tow truck.

It’s easy to assume that because your car is working then there’s nothing to worry about. But if you notice any coloured smoke coming out of the exhaust then it could be a hint that a mechanical problem could be waiting in the wings.

The colour of the smoke that comes out of your car’s can mean different things, and is an indication of what might be wrong. Read on for details that might be worth looking out for.

Vapour

Vapour looks like white smoke but is usually a lot less thick. Generally it’s nothing to worry about, and tends to mean that the engine hasn’t warmed up yet – or that it’s cold outside! Most cars show that the engine is warmed up by a temperature gauge near the speedometer and, if everything’s ok, it should be around the halfway mark. To ensure everything is fine, wait until the engine is warm enough and then check your exhaust again. If it’s still producing smoke, it might be worth checking out.

Black or grey smoke

Any smoke that comes out of your exhaust means that you need to get a garage to check over your car, as it can be unhealthy for your engine or the environment – or both. Black or grey smoke usually means that the engine isn’t running as healthily as it should be, but the associated problems shouldn’t be too time-consuming or expensive to fix.

It can be a range of problems, but the most common ones include a malfunction in the fuel injection system, a clogged air filter, the engine timing being out of sync or a blocked manifold. Once fixed, your car should be back to full health – providing there are no other underlying problems. For diesel cars all of the above apply, but it could also be a sign that the engine is running a bit too hot and overheating, or your diesel particular filter is automatically burning off soot, which is normal once in a while.

Blue smoke

Blue smoke from a car exhaust is generally a bad sign, and the cause of it will need to be repaired as soon as possible. It’s either a problem to do with the oil, or internal engine components. In petrol cars, it might suggest that oil is leaking into the engine block where the fuel is mixed with air, while in diesel cars it may simply suggest that there is too much oil in the engine. In the worst cases, the cylinder heads, pistons or valves might all be worn down. Regardless, you’ll want to get your car looked at by a reputable garage if it’s emitting blue smoke.

White smoke

White smoke also needs to be checked immediately, because it can be a sign that your engine is on its last legs. For diesel cars it can mean that the engine timing isn’t right, that there’s a fault in your fuel injection system, or that the engine is overheating. And if you drive a petrol car and see white smoke, it’s really not good news. It could be that either the cylinder block or head are cracked, or that the head gasket is leaking. If the head gasket is not fixed immediately, it can spell the death of that engine. In some cases the cost to fix this problem is more than the car is worth.

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