Is Your BMW Smoking? What Does This Mean?

So, you’re driving down the road when smoke begins to billow from under your BMW’s bonnet. Panic sets in almost immediately. After all, you’ve been taught all your life that where there’s smoke, there’s fire. Fortunately, this isn’t always the case in the automotive world. Smoke can be caused by a number of different problems, and it doesn’t always mean a fire is present. However, smoke does most often indicate a very serious problem and requires your immediate attention.

Types of Smoke

In general, there are four different types of smoke you may experience when driving a BMW. Depending on the cause, it may be seen coming from under the bonnet or from the exhaust.

• Blue Smoke- Blue smoke is often associated with oil, and most likely means that the engine is burning oil. When this occurs it is important to check car parts like the piston rings and valve guide seals to ensure they are not work out. The car should be checked for oil leaks as well; if a problem is noticed, it should be fixed immediately to avoid causing further damage to other car parts like the engine and spark plugs.

• Grey Smoke- Grey smoke is similar to blue smoke in that it generally indicates oil burning in the engine. However, it can also be caused by the engine burning up automatic transmission fluid in the engine due to a faulty modulator. If the smoke is coming from the exhaust, it can also mean that a PCV, or positive crankcase ventilation, valve is stuck. The PCV is in charge of reducing harmful emissions by recycling them back through the combustion chamber. If the valve becomes stuck, oil leaks can occur. 

• White Smoke- The thickness of white smoke generally determines whether it is a big problem or a small concern. If it thin like a vapour, it is often the result of normal condensation. However, if it is thick and heavy, white smoke can indicate coolant burning in the engine. This often means there is a big problem with BMW parts, like a damaged cylinder head, a cracked engine block, or a blown head gasket. These problems cannot be ignored and must be repaired immediately.

• Black Smoke- Black smoke is often cause by the engine burning too much petrol. The first place you should look is the air filter. If this is clogged, it could produce black smoke. Other car parts should then be examined as well, like fuel return lines, fuel pressure regulators, sensors, and fuel injectors.

What to do if You See Smoke

If you’re driving down the road and smoke begins to come out your exhaust or from under the BMW’s bonnet, don’t panic. Instead, pull over immediately. While smoke doesn’t always mean fire, there’s always a possibility that a fire is present. Continuing to drive the BMW, even at a low speed allows oxygen into the engine compartment, which feeds the fire even more.

If possible, stop in an area that is away from building and people. While cars generally don’t explode like they do on television, any burning wires and plastics can produce noxious gases that can be toxic to you and others around the car.

Make sure any passengers are away from the vehicle and at a safe distance, then call for help. If you are confident no fire is present, call your local mechanic to have the car towed. Do not attempt to drive it. If you are not sure if the car is on fire, always play it safe by calling the local authorities for help. Better to be safe and embarrassed than injured and sorry.

While understanding the different types of smoke and the potential problems with BMW parts behind them can be useful, remember them may be difficult when you’re face to face with billowing smoke. If you experience this problem while driving, just remember to pull over, get out of the car, move away to a safe distance, and call for help.