The Chevrolet km car with a mileage of about 100 thousand km in 2010. User reflection: the engine oil alarm light is lit. Inspection and analysis: the maintenance personnel found that the engine noise was large and the hydraulic tappet was constantly issuing "Da Da Da" noise. Check the level of oil and coolant is normal, there is no sign of high temperature. It was observed that a small amount of oil deposits were deposited on the oil dipstick and the oil filler cap, and the valve chamber cover was basically clean. When the engine is idle, the oil warning lights will sometimes go out automatically. Remove oil sensor and measure oil pressure, 50~70 kPa, too low. Remove the oil pressure gauge and basically have no oil outflow. The measuring point is located above the oil pump, which can directly reflect the output of the oil pump. It seems to be a failure of the oil pump. Remove the oil pan and oil pump. It is found that the filter screen has been blocked up by lump oil deposits and can not be oiled. This is the reason for the failure. The analysis shows that the oil deposit in the oil pan is loosened or suspended in the oil after changing the oil, which blocks the filter and causes the above faults. Troubleshooting: cleaning the filter, replacing the oil pump, idle oil pressure up to 280 kPa, tappet noise disappear, troubleshooting.