Smoke dispersing from under a car's hood could be caused by mechanical failure, overflowing oil, a malfunctioning carburetor or valves that need to be replaced. Determining the smell and color of the smoke, such as black, white, gray or blue, can help decipher the cause of smoke exiting from under the vehicle's hood.
Many times, drivers only notice smoke exiting from under the hood while sitting in idle at a stoplight or after turning off the engine while parked. In fact, the amount of smoke can increase over time. If the smoke from under the hood has an oily smell, it is likely that the vehicle has an oil leak, according to Joseph Auto Service. White smoke can indicate a leak within the engine's coolant system, most commonly known as an antifreeze leak.
Blue or black smoke with an acidic smell is an indication that the vehicle has experienced an electrical malfunction. In this case, wires may be burning under the engine's hood. Smoke coming from the exhaust may appear to be dispersing from under the hood in some cases. White smoke or vapors from the exhaust could indicate that the vehicle engine block or cylinder may be cracked or not functioning.