What Causes a Diesel Engine to Emit White Smoke?
1 Answers
Diesel engine emitting white smoke can be attributed to the following reasons: Low engine temperature: When the engine is just started or the external temperature is low, the phenomenon of white smoke emission is noticeable. This occurs because the engine's own temperature is low, and the combustion chamber and cylinder wall temperatures are also low, preventing the fuel mist from mixing uniformly and completely with air, thereby reducing the quality of the combustible mixture. Unburned diesel molecules are expelled along with the exhaust gases, causing the engine to emit white smoke. Injector malfunction: First, when the injector pressure is adjusted too low or the compression spring force is too weak, the injector's opening pressure decreases, increasing the amount of fuel entering the cylinder, known as excessive fuel supply. In severe cases, fuel is injected into the cylinder in a column-like form. The unburned fuel evaporates and is expelled, causing the engine to emit white smoke. At idle, the smoke appears light white; at high speeds, it appears dark gray. Fuel injection pump malfunction: The delivery valve assembly is one of the precision components in the fuel injection pump assembly. If its sealing performance is compromised, some fuel in the high-pressure fuel line will flow back into the injection pump, reducing the line pressure. At the start of the next injection cycle, a longer fuel supply time is required to compensate and achieve the injection pressure, leading to delayed injection timing. Insufficiently burned fuel is expelled with the exhaust gases, causing the engine to emit white smoke. This type of fault directly reduces the engine's fuel efficiency and power, leading to abnormal fuel consumption. Excessively late fuel supply timing: The timing of the fuel injection pump's fuel supply determines whether fuel is injected into the cylinder too early or too late. If the fuel supply timing is too late, the fuel cannot mix sufficiently with air, reducing the quality of the mixture. Some fuel molecules are expelled without being burned, causing the engine to emit white smoke.
