Despite what old cartoons would have you believe, it’s neither normal nor good for your vehicle to smoke heavily while it’s running. Maybe in the old days, but modern cars with modern fuel injection, cooling systems, and engine management systems are not supposed to smoke. So when you see a smokey car on the road, that’s a sign of a serious problem.
Typically, when a vehicle is having issues, you’ll get two kinds of smoke from the exhaust — blue or white. Blue smoke is usually accompanied by the acrid smell of a car burning oil because oil is getting into the car’s combustion chambers. White smoke, on the other hand, means that coolant is getting into the combustion chambers. Today, we’re going to concern ourselves with the latter.
White smoke coming from your car’s exhaust typically means one of two things – either you have condensation in your engine and exhaust or your engine is burning coolant. If you’re lucky and it’s just condensation, which is typically caused by numerous short trips where the vehicle doesn’t get up to operating temperature or by sitting for long periods of time, that can be fixed by getting the car up to operating temps and keeping it there to burn the condensation off. If you’re unlucky and you’re burning coolant, that’s a bigger problem with a more complicated solution.
How bad could it be?
Coolant can get into your engine’s combustion chambers one of two ways — through a blown head gasket or a crack in the engine (either in the block or the cylinder head). As you can imagine, a crack in your engine is a catastrophic failure, although there are (expensive) ways to fix one. Blown head gaskets, on the other hand, are a more common and easily remedied problem. Head gasket failure can be caused by a number of factors — preignition due to bad or low-octane gas, engine overheating, incorrect installation, abrupt changes in temperature, advanced age or mileage, etc.
Once coolant gets into the engine where it’s not supposed to be, it starts affecting numerous internal systems. The most obvious is the white smoke from the exhaust. You also may notice a sickly-sweet smell like hot butterscotch coming from the front of the car — that’s hot coolant cooking off inside the engine. You’ll slowly lose coolant with a blown gasket, which will make the vehicle run hot and even overheat more often. Additionally, unburned coolant can foul your oxygen sensor, leading to a check engine light and reduced performance as the vehicle’s computer tries to make sense of bad info from the sensor. Obviously, none of this is good or safe for your vehicle.
What do I do now?
If you start seeing white smoke from your exhaust, the first thing you should do is check your oil and coolant. If your oil is thick, milky, or foamy — a condition that mechanics like to call “milkshake” — that’s a good, clear sign of a bad head gasket. You can also get oil in your coolant, which leads to gross and foamy coolant. As you can imagine, contaminating oil with coolant dilutes those fluids and reduces their effectiveness. The longer you run a vehicle with a leaking head gasket, the more your oil and coolant get diluted and the worse these issues become, which can eventually lead to catastrophic engine failure.
The best thing to do if your vehicle is smoking and you have contaminated oil or coolant is to get your vehicle into the shop pronto. Don’t mess around with a leaky head gasket if you value your vehicle. Sure, getting a leaky head gasket replaced can be expensive and annoying, but blowing up your engine because it tried to use coolant as oil is even more annoying and expensive. An ounce of prevention, as they say, is worth a pound of cure.
