1. The defect of piston ring causes oil burning
① The piston ring is bitten by carbon deposit in the ring groove, which loses elasticity and poor sealing. The high-temperature gas flows to the crankcase, causing oil burning. The oil ring is bitten, and the excess oil on the cylinder wall cannot be scraped off to burn the oil
② The piston ring is excessively worn, the elasticity is weak, the opening clearance exceeds the limit, or the piston ring is broken and the seal is not good
③ The clearance between the piston ring and the groove edge of the piston ring increases, so that the oil pump can pump oil from bottom to top along the ring groove
④ The piston ring is out of round and has large light leakage
⑤ The holes on the oil ring and the corresponding piston ring groove through holes are blocked by carbon deposits or sundries, so that the oil ring can not scrape off the oil on the cylinder wall, so that the oil on the cylinder wall can be burned. ⑥ due to the unbalanced section of the twisted ring, torsion occurs during work, which can strengthen the sealing, pump less oil and reduce the oil consumption, The working performance of the conical section ring is far inferior to that of the twisted ring. The wrong installation of the twisted ring and truncated cone ring also causes oil pumping. This fault often occurs after the cylinder barrel piston group is just assembled. It can be judged according to the blue smoke from the exhaust of the locomotive and the understanding of the operator.
2. The defects of cylinder liner and piston cause oil burning
① If the cylindricity and roundness of the cylinder liner are unqualified or the wear exceeds the limit, the matching gap between the cylinder liner and the piston is increased, and the oil flows into the combustion chamber, and the high-temperature gas flows, resulting in oil burning. Generally, when the roundness exceeds 0.5mm or the cylindricity exceeds 0.25mm, its sealing performance is very poor. For the fault, it is necessary to understand the service life of the cylinder barrel and piston Analyze and judge the maintenance situation and auscultation sound. At this time, it can be found that the exhaust emits blue smoke, the exhaust gas from the oil inlet, the oil temperature rises, poor compression and other signs. If the compression force of the cylinder becomes better after adding a small amount of coal extraction cleaning or adding an appropriate amount of oil to the cylinder, it indicates that the matching clearance between the sleeve and the piston is too large.
② The cylinder liner is longitudinally strained and has deep scouring marks, which makes the oil run up along the groove marks and under the high-temperature gas, causing oil burning.
③ The cylinder liner is too thick or the outer water jacket is surrounded by scale, the thermal conductivity is greatly weakened, and the cylinder liner is overheated, causing the oil in the cylinder liner to burn.
④ The cylindricity of the piston skirt is generally small at the top and large at the bottom. On the contrary, it will greatly increase the oil consumption.
3. When the clearance between valve stem and valve guide is too large
The engine oil will enter the cylinder combustion chamber from the clearance and burn. Because when the intake valve is opened, the cylinder will generate suction force on the oil on the guide pipe. Especially when the diesel engine works at a lower speed, the oil consumption will increase exponentially. In serious cases, the oil consumed by the valve train accounts for 30% of the total loss. When auscultating with a screwdriver along the valve installed on the cylinder head, a weak middle tone knocking sound can be heard, At the same time, there will also be blue smoke from the engine oil burning exhaust pipe.
4. The oil level in the oil pan is too high
The crankshaft splashes too much oil on the cylinder wall during operation, causing oil burning. Measure the oil level with an oil dipstick after stopping for 30 minutes.
5. Increased clearance between connecting rod pads
As the oil splashed on the cylinder wall increases, the pump oil volume of the piston ring increases and the oil burning loss increases. The more the clearance of the connecting rod bearing bush increases, the more the pressure value of the oil decreases, and this law exists in various models. At the same time, it can also be analyzed and judged in combination with the auscultation sound.
