Carter Volkswagen Service FAQs: Why is Smoke Coming Out of my Tailpipe?
Smoke coming from the tailpipe of your Volkswagen can tell you a lot. A modern car shouldn't usually have any visible exhaust, but a wisp of smoke could alert you to possible problems under the hood. In fact, a close look at the color of the smoke can give you a great idea of what the problem could be!
If you've noticed smoke coming out of your vehicle's tailpipe, take a closer look. The color and timing of the smoke can tell you a lot about the likely cause. We'll explain below what each color could mean, and what could be done to fix it.
Black Smoke | Caused by a Rich Fuel Mixture
The darkest smoke that comes out black and sooty is actually the one that indicates the simplest problem. It means that the combination of air and fuel your engine is combusting is too rich with gasoline. Not all of the gasoline is burned during combustion. Some is forced out into the exhaust where it emerges as black smoke. Since the fuel ratio is controlled by the engine's ECU computer, momentary black smoke could be fairly normal on an older car. Or, it could be a sign of a bad O2 sensor, a clogged engine air filter or a leaking fuel injector. Replacing these components is a routine procedure in our service department.
Blue Smoke | Caused by Oil In Combustion
Smoke that emerges blue from the tailpipe indicates that your engine is burning a significant amount of oil. Worn out valve seals or piston rings can allow oil to squeeze past and into the combustion chambers, where it will be burned along with the air and fuel. Burning a little bit of oil is okay, especially in an older car where piston ring replacement would be extremely costly. But if your car burns so much oil that blue smoke is noticeable, you may also get a dramatic decrease in power.
Cars with aftermarket performance add-ons often display blue smoke. Adding a turbocharger, for example, puts additional stress on the engine and its various seals — increasing the likelihood of an oil leak.
White Smoke | Caused by Water Vapor or Burning Coolant
On a cold winter day or when your car is just starting up in the morning, white smoke isn't a problem. This smoke isn't even smoke at all, but steam — that is, water vapor.
Overnight, condensation can collect in the exhaust which will turn into steam as your engine warms up. This will be more noticeable on cold days, but, in general steam coming from the tailpipe before the engine warms up is nothing to worry about.
Having said that, if it's a moderate temperature outside and the engine has warmed up, yet you're still seeing white smoke, keep a close eye on your temperature gauge. You may be dealing with a blown head gasket.
When a head gasket fails, coolant can be allowed to leak past the gasket and into the combustion chambers, where it is burned. The water inside the coolant turns into steam, and then billows dramatically from the tailpipe. Burning coolant isn't a problem — but the blown head gasket that caused it is. Eventually, there won't be enough coolant left to keep the engine cool, and catastrophic damage will occur when the engine overheats.
So, if you see lots of white smoke emerging from the tailpipe on a warm summer day, pay close attention — and be prepared to pull over and stop the car if it begins to overheat.