The smoke from the factory is tested in accordance with the relevant standards and will not emit black smoke under normal operating conditions. only when the overload works, the diesel engine will emit black smoke.  It is not normal for a diesel engine to emit black smoke when it is in a state of air or in a small load, or excessive black smoke at a heavy load.  

 1. the fuel injector is poor at work: the fuel injector atomized bad or drip oil is particularly obvious at low speed of diesel engine, the lower rotating speed is more smoke, the single cylinder fault oil method can be searched by cylinder one by one, and the phenomenon of black smoke can be reduced or disappeared when the fuel supply is temporarily stopped. if the fuel injection pump is working normally, it can be determined to have trouble for the injector.  The injector parts of the fuel injector shall be cleaned, grinded or replaced, as the case may be.  

 It is not only the big pump truck will emit black smoke., after the emission upgrade, the vehicle has more EGR system, such as uneven fuel supply, premature injection time and inadequate atomization will lead to black smoke.  If the EGR valve fails to fail, the vehicle enters the engine during the driving or idling process.  After mixing with the exhaust gas, the air content in the intake side of the cylinder will be reduced, resulting in a decrease in oxygen, and the fuel combustion does not fully increase the content of the carbon in the exhaust gas, and the exhaust gas will become black.  

 2. improper adjustment of the fuel supply advance angle: the fuel supply advance angle is too small, and the rear fuel is increased, the fuel cannot be completely burned, and the carbon smoke is formed, resulting in the exhaust fumes.  At this point, the fuel supply advance angle should be adjusted to the appropriate position.  

 3. the fuel supply to the fuel injection pump is too large: the smoke is too large, and the black smoke is continuous, and the greater the throttle, the greater the smoke, the more black smoke can be inspected. when a cylinder stops oil, if the smoke disappears, it can be determined that the oil quantity is too large in the normal working conditions of the fuel injector, and the oil quantity of the cylinder should be properly adjusted, and the fuel injection pump will be dismantled if necessary, and the test rig will be debugged.  The reason for the excessive oil supply is that there is error in the correction of the fuel injection pump, resulting in an excessive amount of oil;  The adjusting screw of the oil pump oil quantity increases the amount of oil;  The timing screw loose on the tappet of the fuel injection pump, and the interval angle changes;  The smoke limiter falls off and the smoke is very large at startup.  

 4. the air filter plugging of the accessories parts of Baotou north heavy duty truck: after the blockage of the air filter element, the intake air of the diesel engine is reduced, the same amount of diesel oil is injected into the cylinder, and there is not enough air to mix it, and the diesel can not be fully burned to produce black smoke.  The air filter element should be replaced.  

 5. the diesel engine load is too heavy: when the vehicle is speeding up, climbing uphill or the diesel engine exceeds the load, the diesel fuel injected into the combustion chamber increases, but the mixture of excessive diesel and air is not evenly distributed., the diesel engine will not be able to avoid the burning of the local air., in the case of high temperature and high pressure oxygen, the diesel fuel will be decomposed into carbon smoke, which will emit black smoke with the exhaust gas.  The overload should be avoided in the vehicle operation to the maximum extent possible.  

 6. the quality of diesel is not good: the diesel engine uses inferior diesel oil, or the diesel oil contains other impurity fuel, so that the combustion is not sufficient and the emission of black smoke.  

 7. other reasons: not enough compression ratio, excessive or too small valve clearance, valve sticking or tight seal of valve and valve seat, and wear of piston ring and cylinder liner are important reasons for the emission of black smoke from diesel engine.  

 Three conditions trigger white smoke

 Enter the cold winter, the diesel engine cold start when the white smoke, if the speed increase, white smoke disappears, belongs to the normal phenomenon.  However, after the hot car, the exhaust pipe still emit white smoke, it is decided that the diesel engine work is not normal, should be checked and excluded.  

 1. the fuel supply advance angle is too small: when the temperature of the diesel engine is not high, part of the fuel oil will be discharged with the exhaust gas before it is too late to burn, and the diesel oil mist discharged will form white gas.  

 2. cooling water enters into the cylinder: the leakage of the cylinder head or the flushing of the cylinder cushion is connected with the water channel, so that the cooling water enters into the cylinder, and the white smoke is formed when the exhaust gas is discharged.  If there is too much water in the cylinder, the engine can not start, if the car drag to start, the water in the cylinder can not be compressed, the piston upward, causing the connecting rod bending, so the cylinder inside the water should not be dragged to start, so as to avoid the expansion of the fault.  In addition, diesel engine water, low injection pressure, diesel fuel atomization, and so on will cause the white smoke of diesel engine, should be checked and eliminated in time.  

 3. other reasons: the cold season, cold start or the fuel injector has serious drop oil phenomenon when the exhaust fumes white smoke, this phenomenon is most common in the cold area.  If the above reasons are excluded, the engine is still white smoke, can check whether there is a cylinder intake pipe plug, the intake of the air intake cylinder lead to the diesel engine not burning, will also cause the engine to emit white smoke.  

 Five cases of blue smoke

 The diesel engine exhausts the blue smoke, is the lubricating oil enters the combustion chamber to participate in the combustion, and the combustion does not completely present the blue smoke eduction.  The reason why lubricating oil enters the combustion chamber is as follows:

 1. the oil pan oil level is too high: the oil pan oil level is too high, the oil is driven by the crankshaft and connecting rod big head along the cylinder wall into the combustion chamber, so that the diesel engine is exposed to blue smoke.  

 2. oil leakage of valve guide oil seal: the gap between valve stem and guide tube is too large or the oil seal is aging, worn and worn out. the indoor lubricating oil of the rocker arm enters the combustion chamber between the valve stem and the guide tube, so that the diesel engine is exposed to blue smoke.  Check to confirm which valve oil seal has a problem, can remove the exhaust pipe, observe the exhaust valve, if the hair wet, which cylinder of the oil seal failure.  When replacing the oil seal, do not remove the rocker arm group, just press the valve of the cylinder of the oil change oil seal, set the rocker arm to the side, and then swing the cylinder piston to the top dead center, and then remove the valve spring, and then replace the valve oil seal.  

 3. excessive clearance between the valve guide and the valve stem: the gap between the valve guide and the valve stem is too large, and the oil enters the combustion chamber along the inner wall of the valve due to the suction when the piston is down, resulting in the burning oil.  

 4. the wear of piston ring and cylinder liner of Baotou heavy duty truck in Baotou is serious: the wear of piston ring and cylinder liner, the anti – piston ring, the piston ring in the cylinder or the piston ring in the ring groove will cause oil to enter the combustion chamber, and the diesel engine will take the blue smoke.  

 5. excessive clearance between the piston and the cylinder liner: the gap between the piston and the cylinder liner is too large to cause the oil breakthrough, and it needs to change the piston and cylinder to meet the specified standards.  In addition, idle load idle running time is too long, also will make the diesel engine blue smoke.  Should minimize the low speed air load operation, prevent the tube oil seal overheating, lubricating oil enters the combustion chamber between the valve guide tube, causing the engine to take blue smoke.  

 ● afterword:

 As a transport vehicle, the good operation of the truck is directly related to the economic interests of the user.  As the heart of the truck, Baotou north heavy truck spare parts engine directly affects the operation efficiency of the users. as more and more technology is used in the truck, it is more and more complicated to judge the cause of the vehicle fault. only careful analysis, accurate judgment can bring more efficiency for the users.