Reasons for White Smoke from Diesel Engines?
2 Answers
Here are the detailed explanations for the causes of white smoke from diesel engines: 1. Light white smoke, water in diesel fuel: Diesel fuel needs to settle for 24 hours before use. When refueling, avoid inserting the fuel pump to the bottom of the diesel barrel. Damaged or missing fuel tank caps should be promptly replaced. Poor sealing of the cylinder head gasket or cracks in the bottom of the cylinder head can cause coolant from the water jacket to leak into the cylinder, forming water vapor and resulting in white smoke. Locate the leakage point and repair or replace the relevant parts. 2. White smoke: When the temperature is too low, some diesel fuel may not ignite and burn, producing white smoke. This white smoke will disappear on its own as the engine temperature rises, which is a normal condition and does not require troubleshooting. Low injection pressure, severe dripping of the injector, or excessively low injector pressure adjustment can cause some diesel fuel mist to fail to ignite and burn in the combustion chamber, resulting in white smoke.
I previously encountered a situation where a diesel engine was emitting white smoke, and found that the most common cause is water mixed into the diesel fuel. When water enters the cylinder and is heated, it turns into steam, which is expelled as white smoke. This also tends to happen during cold starts in winter, especially with older machines, where poor atomization in the fuel injector leads to incomplete combustion of the diesel. Once, while repairing agricultural machinery, I saw a case where the cylinder head gasket was damaged, allowing coolant to leak into the combustion chamber, which also resulted in thick white smoke. Additionally, incorrect fuel injection timing—either too early or too late—can cause smoke emission. To address this, first check if there is any accumulated water in the fuel-water separator, and then monitor whether the coolant level in the radiator is dropping significantly. If the smoke persists even after the engine has warmed up, it's a serious concern, and you may need to inspect the cylinder compression and fuel injectors.
