Agricultural machinery diesel engine as an example
1. Emission of blue smoke:
The reason for emitting blue smoke is that there is excessive engine oil burning in the combustion chamber. The reasons and elimination methods of this phenomenon are as follows:
(1) Too much oil is added to the oil pan. If there is too much oil, it will splash with the high-speed crankshaft to the cylinder wall and enter the combustion chamber. The elimination method is to stop the machine for about 10 minutes, check the oil scale, and remove the excess oil.
(2) The cylinder liner and piston ring assembly are badly worn and the gap is too large. As a result, a large amount of engine oil will flow into the combustion chamber for combustion, accompanied by increased crankcase exhaust gas. The processing method is to replace worn parts in time.
(3) The piston ring has failed. If the piston ring has insufficient elasticity, it is stuck in the ring groove by the carbon deposit, or the ring mouth is on the same straight line, or the oil return hole of the oil ring is blocked, it will cause the engine oil to enter the combustion chamber and burn, and blue smoke will appear. The treatment method is to remove the piston ring, remove the carbon deposits, rearrange the buckle, and replace the components if necessary.
(4) The gap between the valve and the catheter is too large. During intake, a large amount of engine oil in the rocker arm enters the combustion chamber and burns. The treatment method is to replace worn valves and catheters in time.
(5) The reason for emitting blue smoke is that if the engine oil is too thin, the engine oil pressure is too high, and the engine is not running in properly, it will cause the engine oil to burn and emit blue smoke.
2. Smoke exhaust and black:
This phenomenon is caused by incomplete combustion of fuel. When black smoke is emitted, it is often accompanied by a decrease in engine power, an excessively high exhaust temperature, and an excessively high water temperature, which causes several pieces of the engine to wear and affect the life of the engine. The reasons and elimination methods of this phenomenon are as follows:
(1) Insufficient intake air or blocked intake pipe. In order to find out the reason, the following inspections should be carried out: whether the air filter is blocked; whether the intake pipe is leaking; whether the turbocharger is damaged.
(2) Improper adjustment of valve clearance. Poor contact of the valve sealing ring. Check valve clearance, valve spring and valve sealing ring.
(3) The supply of each cylinder of the high-pressure oil pump is uneven or too large. As a result, the rotational speed is unstable and black smoke is emitted intermittently, which should be adjusted to make it balanced or within the specified range.
(4) If the fuel injection is too late, the fuel injection advance angle should be adjusted.
(5) The fuel injector works badly or is damaged, it should be removed for inspection.
(6) The cylinder liner and piston ring assembly are seriously worn. When this happens, the piston ring is not tightly sealed, and the air pressure in the cylinder drops, causing the diesel engine to not fully burn and emit black smoke, and the engine power drops sharply. In severe cases, the engine will automatically shut down when under load. Wear parts should be replaced.
3. Emission of yellow smoke:
The yellow smoke is discharged in the middle speed stage at the initial stage of the start-up operation. After the temperature is increased or the load is increased, the yellow smoke is gradually reduced or eliminated. The performance is that the idle speed is easy to extinguish, the body shakes, and the intake pipe "choke" and the exhaust pipe fires. The power is insufficient and the start is difficult. The reasons for this phenomenon and the troubleshooting methods are as follows
under:
(1) Individual intake and exhaust valves are not closed properly, or the spring force of the valve spring is insufficient, the valve push rod is bent, and the intake and exhaust valves are ablated. The treatment method is: grinding the valve, removing carbon deposits, and replacing worn parts.
(2) The gap between the camshaft journal and the seat hole is too large or the valve phase is inaccurate. Most valves are ablated, and the cylinder liner and piston ring are worn out too much. The solution is to adjust the gap and replace the worn parts.
