Blue smoke from engine burning oil

It is normal for the engine to burn a small amount of oil. It is normal for the machine to run normally and consume a certain amount of oil (within the specified value). Greatly prolong the service life of the engine.

Diesel engine burns oil, the main performance is blue smoke from the exhaust pipe. When the load is heavy, the exhaust pipe emits black smoke, black oil seeps from the joint of the exhaust pipe, and there is often black oily smoke at the outlet of the exhaust pipe. Wet Lulu. The reason for the failure is :

1. Valve guide oil seal leaks oil

If the oil leakage of the valve guide oil seal or the oil leakage of the valve rocker arm group is serious, the oil cannot flow into the oil pan in time and splash to the upper end of the intake and exhaust valves. Due to the up and down movement of the valve, the valve guide oil seal cannot bear a large amount of oil and follows the movement of the valve stem. Down into the combustion chamber, the excess oil is discharged into the exhaust pipe through the exhaust valve; after part of the oil is burned, the blue smoke is discharged through the tail end of the muffler.

Diagnosis method: first remove the cylinder head cover, start the engine to run quickly, find out the serious oil leakage of the valve rocker group, check whether the valve guide oil seal is invalid, if it is invalid, remove the exhaust pipe to determine which cylinder's guide oil seal leaks oil. . Pay attention to the tightness of the oil bag on the conduit when replacing.

2. There is too much oil in the oil pan

There is too much oil in the oil sump, and the agitation of the connecting rod and crank makes a large amount of oil splash on the cylinder wall, and is brought into the combustion chamber by the piston and piston ring for combustion. Lack of timely return.

3. Piston ring counterparts

The piston rings are facing each other, so that the engine oil enters the combustion chamber from the counterpart, causing the phenomenon of burning engine oil and causing insufficient power.

4. The piston ring is reversed

The piston ring is stuck backwards, so that the engine oil enters the combustion chamber, causing the phenomenon of burning engine oil.

In addition, excessive wear gaps such as piston rings, pistons, and cylinder liners will also cause engine oil to burn. Pay attention to the direction of the piston ring when assembling. The marked side of the first ring faces up, and the grooved side of the second outer ring faces down. When the wear of piston rings and cylinder liners exceeds the limit, new piston rings and cylinder liners should be replaced in time.

5. Severe oil discharge or exhaust at the respirator port

Reasons for severe oil or exhaust from the respirator port are:
1. Too much oil in the oil pan and severe exhaust from the bottom.
2. After the cylinder is pulled, the gas enters the crankcase and is discharged by the respirator.
3. In the oil return hole of the push rod cavity, the flash is too large, resulting in the oil return hole being too small. When the diesel engine is running at high speed, the oil in the rocker arm cavity is blocked and blocked, so that it is discharged from the breather. 4. The diaphragm plugs at both ends of the rocker shaft fell off, and the gap between the rocker shaft and the rocker arm was too large, resulting in serious oil leakage from the valve rocker group. When the oil return hole of the push rod cavity is too small, the oil cannot flow into the oil pan in time. Clogged oil is expelled from the breather.
5. Piston ring alignment, jamming, serious wear of piston ring, loss of bullets, excessive wear of cylinder liner, and large out of roundness will destroy the airtight effect of the cylinder and cause serious lower exhaust, which should be checked and eliminated in time.

6. The water temperature is too high

When the Chaoyang diesel engine is working: the cooling water temperature is required to be kept at 75-90°C. If the temperature is too low, it will accelerate the wear of parts, and if the temperature is too high, it will cause other failures. Reasons for high engine water temperature are:

1. The thermostat is damaged.
The thermostat of the diesel engine is a wax-type thermostat. It starts to open when the water temperature is 76°C; it is fully open when the water temperature is 86°C. Due to the damage of the thermostat or the stuck valve core, the main valve cannot be opened or the opening is very small, which makes the heat dissipation efficiency of the high-temperature water circulation of the diesel engine worse.
2. There is air in the water pipe
. After the diesel engine is started, there is no water in the water pipe or the water volume is very small, and the water temperature continues to rise. For cars with auxiliary water tanks, after the engine temperature rises, adding water will easily cause air resistance, resulting in empty satiety and high temperature.
3. The fan belt is too loose.
When the tension of the fan belt is 39N·m (4kgf·m), the deflection is between 10 and 15mm. If the fan belt is too loose, the fan belt and the water pump wheel will slip, resulting in insufficient water supply from the water pump. Diesel engine water temperature is too high.
4. Insufficient or uneven tightening torque of cylinder head screw inspection
When the tightening torque of cylinder head bolts is uneven (or when the cylinder head gasket is flushed), high-pressure gas will also enter the water jacket, and the cooling water in the water tank will bubble and spray water. This is more noticeable when the diesel engine is accelerating.
5. The heat dissipation area of ​​the water tank is not enough.
Most of the heat in the cooling water is dissipated by the heat sink of the water tank. If the heat dissipation area of ​​the water tank is too small, the cooling water will boil due to insufficient heat dissipation. Some drivers have poor mechanical knowledge. When adding cooling water, what is added is raw water or dirty water in the river. After driving tens of thousands of kilometers, the scale will gradually block the cooling pipeline of the water tank, making the circulating water not smooth and the water temperature too high. How to diagnose water tank blockage:
① Fill the water tank with water first, and then run the engine. When the vehicle speed is increased to medium or high speed, if there is a small amount of water turning over at the water inlet, it means that the water tank is slightly blocked. If the water tank turns over a lot, it means that the water tank is seriously blocked.
② If there is no obvious reaction, raise the water temperature to above 85°C, and then perform repeated accelerator tests at medium and high speeds. At this time, if the water tank turns over or bubbles, it means that the cooling pipe of the water tank is slightly blocked or severely blocked.
6. The advance angle of fuel supply is too small
If the advance angle of fuel supply is too small, a large amount of fuel will be injected into the cylinder in the later stage, the amount of fuel burned in the rapid combustion stage will be small, the secondary combustion will increase, the efficiency will decrease, and the temperature of the diesel engine will be too high.
The fuel supply advance angle should be adjusted correctly according to the requirements of each model.

7. The long-term heavy load or overload work of the diesel engine is also one of the reasons for the high temperature of the diesel engine.