Judging diesel engine exhaust gas color, fault diagnosis and maintenance

Diesel fuel combustion, the normal color is generally light gray, dark gray heavy load. The diesel engine at work, occasionally there will be a row of black smoke, white smoke, smoke and other abnormal phenomenon, it is the judgment of diesel engine fault conditions, analysis as follows:

(1) black smoke

Diesel is a complex hydrocarbon that is injected into the combustion chamber, and unburned diesel is decomposed at high temperature to form carbon black. Exhaust with exhaust gas to form black smoke. Black smoke is a manifestation of incomplete combustion of fuel in a combustion chamber. The main influencing factors are as follows:

1, piston ring, cylinder liner and other wear

When the piston ring and cylinder liner are worn, the compression pressure is not enough, so that the normal proportion of the mixture will be changed at the end of the compression stroke, so that the fuel will burn in the oxygen free condition and the coke will be produced.

2 、 the injector is not working well

The fuel injector does not atomizing or dripping oil, so that the fuel can not be fully mixed with the air in the cylinder, and can not be fully combusted. The phenomenon of soot exhaust caused by poor injector operation is obvious when the diesel engine runs at low speed. Because of low speed cylinder swirl is weak, oil droplets or oil flow to reduce the possibility of beam break up and stay longer, more easy to form carbon black discharge.

3, combustion chamber shape change

The manufacturing quality of combustion chamber shape does not meet the technical requirements, the compression I sewed too too small and the position of the piston installed wrong, will cause the change of the shape of the combustion chamber, thus affecting the fuel mixed with air quality, so that the fuel combustion conditions deteriorate.

4, oil supply advance angle adjustment inappropriate

1) fuel supply advance angle is too large, too early fuel injected into the combustion chamber, the cylinder pressure due to low temperature, fuel combustion, when the piston, cylinder reaches a certain pressure and temperature, the combustible mixed gas combustion.

2) the fuel supply advance angle is too small, the fuel injected into the cylinder is too late, some of the fuel is too late to form, the combustible mixture is separated or discharged, and the fuel discharged with the exhaust gas is decomposed at high temperature to form black smoke.

5. excessive fuel supply

Excessive oil supply, so that the amount of oil into the cylinder increased, resulting in more oil, less gas, fuel combustion is incomplete. In addition, heavy work load, poor fuel quality and low operating temperature will cause soot exhaust.

(two) blue smoke

The oil enters the cylinder and evaporates into blue gas. Blue smoke is discharged with the exhaust gas, mainly due to:

1, air filter element, air intake or poor tank oil level is too high (oil bath air filter).

2, the fuel mixed with lubricating oil.

3, piston ring counterpart,

4. The cylinder liner near the cylinder head is burned down.

5, piston ring, piston, cylinder liner wear

(three) white smoke

When the diesel engine starts or dies in a cool state, the exhaust pipe emit white smoke because of the low temperature and the evaporation of the oil vapor in the cylinder of the diesel engine. Especially in winter. If the engine is still emitting white smoke, the engine is judged to be a diesel engine fault. The main reasons are as follows:

1, the cylinder liner cracks or cylinder pad damage, cooling water into the cylinder, when the exhaust water mist or water vapor.

2, fuel injector atomization is bad, there is a drop of oil phenomenon.

3, oil supply advance angle is too small.

4 、 there is water and air in the fuel.

5, fuel injection pump pressure is too low, or piston, cylinder liner and other serious wear and tear, resulting in insufficient compression force.