Causes and Solutions of Low Engine Oil Pressure

During the operation of the engine, if the oil pressure is lower than 0.2Mpa or fluctuates as the engine speed changes, or even suddenly drops to zero, you should immediately stop the machine to find the cause, and continue to work after troubleshooting, otherwise Causes major accidents such as burning tiles and pulling cylinders. Therefore, during the use of the engine, the pressure of the oil must be given great attention. The main reasons and solutions for the low oil pressure are described below:
  1. Insufficient oil quantity If the oil quantity is insufficient, the oil quantity of the oil pump will be reduced or the oil will not be on the pump due to the intake of air, which will cause the oil pressure to drop. abrasion. The oil level in the oil pan should be checked before each shift to ensure a sufficient amount of oil. 2. The engine temperature is too high. If the engine cooling system has serious scale, poor work or the engine is overloaded for a long time, or the fuel injection pump is too late, it will cause the engine to overheat. This will not only accelerate the aging and deterioration of the oil, but also It is easy to dilute the oil, and a large amount of oil is lost from the fit gap, resulting in a drop in oil pressure. The scale in the cooling system pipeline should be removed; the fuel supply time should be adjusted; the engine should be operated at the rated load. 3. The oil pump is stopped. If the drive gear of the oil pump is cut off or the fitting key is cut off, and the oil pump sucks in foreign objects, the oil gear will be stuck. Both will stop the oil pump and the oil pressure will drop to zero. Damaged pins or keys should be replaced; filters should be set at the oil pump suction port. 4. The oil output of the oil pump is not enough. When the clearance between the oil pump pump shaft and the bushing, the gap between the gear end face and the pump cover, the tooth side clearance or the radial clearance exceeds the allowable value due to wear, it will cause the pump oil volume to decrease. , Resulting in the consequences of a decrease in lubrication pressure. The out-of-tolerance parts should be replaced in time; the surface of the pump cover should be ground so that the gap between the end face of the gear and the gear can be restored to 0.07-0.27mm. 5. The clearance between the crankshaft and the bearing is too large. 长期 After the engine has been used for a long time, the clearance between the crankshaft and the connecting rod bearing gradually increases, so an oil wedge cannot be formed, and the oil pressure also decreases. It is determined that each time the gap increases by 0.01 mm, the oil pressure decreases by 0.01 Mpa. It can grind the crankshaft and select the corresponding size connecting rod bearing to restore the fit clearance to the technical standard. 6. Oil filter is blocked When the oil cannot be circulated due to the filter being blocked, the safety valve provided on the base of the filter is pushed open, and the oil directly enters the main oil passage without filtering. If the opening pressure of the safety valve is adjusted too high, the filter cannot be opened in time when the filter is blocked. Therefore, the pressure of the oil pump increases, the internal leakage increases, and the oil supply to the main oil passage decreases accordingly, causing oil pressure. Decline. The oil filter should always be kept clean; the opening pressure of the safety valve should be adjusted correctly (usually 0.35-0.45 Mpa); the spring valve or the mating surface of the ground steel ball and the valve seat should be replaced in time to restore its normal working performance. 7. The oil return valve is damaged or malfunctioning. To maintain the normal oil pressure in the main oil passage, an oil return valve is provided here. If the return valve spring is softened or improperly adjusted, when the mating surface of the valve seat and the steel ball wears or gets stuck due to dirt and closes improperly, the oil return volume will increase significantly, and the oil pressure in the main oil passage will also decrease. The oil return valve should be overhauled and its starting pressure should be adjusted between 0.28-0.32 Mpa. 8. Oil leak from oil radiator or pipeline. The oil leakage will both dirty the engine and reduce the oil pressure. If the pipeline is blocked by dirt, the oil flow will decrease due to the increase in resistance, resulting in a drop in oil pressure. The radiator should be taken out, repaired or replaced, and used after pressure test; remove pipeline dirt. 9. Pressure gauge failure or oil pipe clogging If the pressure gauge fails, or the oil pipe from the main oil passage to the pressure gauge fails to circulate due to dirt accumulation, the oil pressure will drop significantly. When the engine is idling at low speed, loosen the oil pipe joint slowly, determine the fault location according to the oil flow, and then wash the oil pipe or replace the pressure gauge. 10. The blockage of the oil suction plate causes the pointer of the pressure gauge to flicker. In general, the indication of the oil pressure gauge should be higher at large throttles than at small throttles, but sometimes abnormal conditions may occur. If the oil is too dirty and sticky, it is easy to block the oil suction plate. When the small throttle of the engine is running at low speed, the oil pressure of the oil pump is not large, and the main oil passage can still establish a certain pressure, so the oil pressure is normal; but when When the throttle is increased at high speeds, the oil suction capacity of the oil pump will be significantly reduced due to the excessive resistance of the suction cup, so the value indicated by the oil pressure gauge of the main oil passage will be reduced instead. The oil suction disc should be cleaned or the oil should be changed. 11. Incorrect or unqualified engine oil grades Different types of engines must be added with different engine oils. Different models of engine oils should be used for the same model in different seasons. If it is used incorrectly or the brand is wrong, the oil leakage will be increased because the oil viscosity is too low when the engine is running, which will reduce the oil pressure. The oil should be selected correctly, and the oil should be selected reasonably as the season changes or the region is different. At the same time, diesel engines must use diesel engine oil, and gasoline engine oil is not allowed to replace it.