Answer : The engine emits blue smoke at low temperature or under low load, and turns into dark gray smoke when the temperature rises, and the power is insufficient.
⑴ Reason
When the engine is running, the exhaust pipe emits blue smoke because the oil enters the combustion chamber and fails to burn when the engine is at a low temperature or a small load, and it is discharged in blue smoke. But when the engine temperature rises or the load increases, the oil vapor is burnt, and it is dark gray smoke again. The reasons for the above phenomenon are:
- The air intake is not smooth, causing the oil in the supercharger to be sucked into the cylinder for combustion.
- There is too much oil in the oil pan, and the oil exceeds the maximum limit.
- The valve guide is filled with oil.
- The cylinder is seriously leaking the oil.
- The supercharger rotor shaft is seriously worn, and the oil baffle ring is damaged, so that the supercharger cannot reach the rated speed and oil leaks.
(2) Diagnosis and treatment methods
- Check whether the intake air is smooth, and check whether there is organic oil in the supercharger shell.
- After turning off the engine for 5_m_i_n_ , take out the oil dipstick and check whether the oil in the oil pan exceeds the maximum limit; if it exceeds, the excess should be released.
- If the above inspections are normal, the fuel injector can be removed to check whether the nozzle holes of the needle valve pair are unobstructed.
- Check whether the oil seal at the upper end of the valve guide and the clearance between the guide and the valve stem are too large. Further, the cylinder head should be removed to check whether the piston ring is stuck in the ring groove, the end gap is opposite, broken, the elastic force is weakened, whether the tapered ring or twist ring is installed reversely, whether the piston, piston ring and cylinder are too worn or not. There is no phenomenon such as pulling the cylinder. If there is any abnormal situation, it should be repaired in time.
- Whether the oil seal of the rotor shaft of the turbocharger is damaged due to improper use and untimely maintenance, and the oil leaks, which is mixed with fresh air into the cylinder, or is vaporized by high-temperature exhaust gas when it is discharged with the exhaust gas from the turbine end. Whether the turbocharger rotor shaft leaks oil, it is clear at a glance when the inlet and outlet pipes are disassembled. If the oil leaks, the oil seal should be replaced, the carbon deposits of the turbine should be removed, and the bearing clearance of the rotor shaft should be checked to avoid damaging the new oil seal.