The diesel engine exhausts blue smoke at low temperature or light load. It becomes dark gray smoke after the temperature rises and the power is insufficient.

What is the reason when we met this problem?

Blue smoke is being exhuasted from the exhaust pipe when the engine is running. It is due to the oil entering the combustion chamber, blue smoke is discharged when the engine fails to burn when the engine is at low temperature or light load. But when the engine temperature increases or the load increases, the oil vapor is burned and it has dark gray smoke again.

The reasons for the above phenomenon are:

Poor intake: the oil in the turbocharger is sucked into the cylinder and burned.

Too much oil in the oil pan: The oil exceeds the maximum limit.

The valve guide enters the engine oil.

Severe oil leakage in the cylinder.

The turbocharger rotor shaft is severely worn and the oil baffle ring is damaged, causing the turbocharger to fail to reach the rated speed and leak oil.

How to make the judgement and solve this kind of problem?

Check whether the air intake is unblocked and whether there is organic oil in the turbocharger shell.

Pull out the oil dipstick after turning off the engine for 5 minutes, and check whether the oil in the oil pan exceeds the maximum limit: if it exceeds, discharge the excess part.

If the above inspections are normal, you can remove the fuel injector and check whether the nozzle hole of the needle valve pair is unblocked. If the carbon deposit is serious or there is oil stain, it means that the organic oil in the cylinder has escaped.

Check whether the oil seal at the upper end of the valve guide and the gap between the guide tube and the valve stem are too large. Furthermore, the cylinder head should be removed to check whether the piston ring is stuck in the ring groove, the end gap is aligned, broken, the elasticity is weakened, whether the conical ring or twisted ring is installed reversely, whether the piston, piston ring and cylinder are worn out or not. There is no phenomenon such as pulling the cylinder, if there is any abnormal situation, it should be repaired in time.

Whether due to improper use and untimely maintenance, the turbocharger rotor shaft oil seal is damaged and oil leaks, mixed with fresh air into the cylinder, or vaporized by high temperature exhaust gas when discharged from the turbine end with exhaust gas. Whether the turbocharger rotor shaft is leaking oil, it is clear at a glance if the inlet and outlet pipes are disassembled. If the oil leaks, replace the oil seal and remove the carbon deposits on the turbine. Check the bearing clearance of the rotor shaft to avoid damage to the new oil seal.

After all aboving operation, I believe the engine can works well.