What causes white smoke in a diesel engine?

Diesel engines often emit smoke during work, which makes many drivers nervous.

Today, we will give you my private collection of "engine white smoke detection troubleshooting".

If the experienced drivers encounter problems such as smoke from the engine, they can also make fault diagnosis according to the troubleshooting methods given.

Under normal working conditions, the exhaust of the diesel engine should be colorless or light gray. In addition, the exhaust smoke color of the diesel engine under idle speed, high speed and high load may be heavier. We should pay attention to observe the normal exhaust smoke color. In order to identify abnormal exhaust smoke.

If the diesel exhaust is white (gray white), you can confirm that the smoke is abnormal. The following is an analysis of the causes of white smoke evacuation phenomena.

Exhaust white smoke

cause of issue

The white smoke is mainly caused by incomplete combustion or water in the oil supply system, which causes the diesel to become oil vapor, and the discharge is white.

1. The working temperature of the engine is too low,and some of the diesel fuel becomes oil vapor when it is not burned. It is discharged from the exhaust pipe with the exhaust gas and emits white smoke.

2.There is water in the oil supply system. There is moisture in the fuel or in the combustion chamber (there is water in the fuel chamber, which may be caused by the rupture of the cylinder liner and other parts, causing the water to enter directly). The water is heated into water vapor in the cylinder and discharged from the exhaust pipe to form white smoke.

3.Fuel injection problem. Poor fuel injection or atomization causes the diesel to not fully burn or because the oil supply angle is too small, the injection time becomes late, the cylinder temperature has decreased when the fuel is injected, and some of the diesel fuel becomes oil vapor when it is not burned, and white smoke is emitted.

4.When the cylinder pressure is too low, some of the diesel fuel becomes oil vapor without being burned, and white smoke is discharged from the exhaust pipe.


1. During the rainy season, late autumn or winter, the temperature is low. When the engine is first started, we can often see white smoke. Once the engine temperature rises, the white smoke will disappear and this condition does not have to be repaired.

2.The diesel engine is weak and white smoke. You can put your hand close to the exhaust pipe. When the white smoke passes over the surface of the hand, there is water droplets indicating that there is water in the cylinder. At this time, the single cylinder oil cut method can be used to find the leaking cylinder. If the single cylinder breaks the oil and affects the speed of the diesel engine, it indicates that the cylinder works well. Otherwise, the cylinder does not work. The injector should be removed to check that there is no trace on the nozzle. If water is found, check the cause of water inflow. Whether the cylinder is broken or the cylinder head is broken; if the cylinders are the same, they still can't work white smoke. Open the fuel tank and the fuel filter's drain screw to check if there is water in the diesel.

3.When the water temperature is around 70 °C, the color of the smoke turns from white to black, and it can be judged that the injector is poorly atomized and dripping. Use the cylinder-by-cylinder method to find the faulty injector and then calibrate the injector; if there is dripping during fuel injection, it should be further checked whether the injection pressure is too low or the needle body is deformed. Or caused by excessive wear and thus improved.

4.When the diesel engine started, it smoked white smoke, and when the temperature rises, it turns into black smoke. This indicates that the cylinder pressure is insufficient. See the black smoke solution.

5.When the diesel engine runs at high speed, the work is uneven, the acceleration is not sensitive, the temperature is too high, the work is weak, and the exhaust pipe is gray and white smoke. This indicates that the injection time is too late. Check and adjust the fastening condition of the fixing plate of the connecting plate and the key and key way. Slowly advance the injection time to eliminate the white smoke and the engine is running normally. If it is still not improved after the adjustment, it should be checked. Whether the timing adjustment screw of each plunger of the fuel injection pump is out of adjustment.



Contact: Wigo

Phone: 19922967201

Tel: 19922967201


Add: No. 70-19, Banshan First Village, Zhongliangshan Street, Jiulongpo Dist, Chongqing city,China.

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