Symptom: the engine idling operation, the top of the cylinder head "flap" light crisp metal percussion, high-speed operation when the sound messy. Driving distance: 57800km.
     Failure analysis and exclusion: This car in the oil by adding an additive soon after the emergence of abnormal sound, according to experience, to determine the abnormal sound is the valve sound, with the stethoscope plus child carefully listen to the valve has abnormal sound. Check the oil pressure is normal. Release the oil, found thicker than the normal oil. After a while, the lower oil is thicker. Replace the new oil after the test, found that abnormal sound becomes smaller, especially when the noise is significantly reduced. Remove the valve room and find a layer of sludge on the surface of the cylinder head. And then install the valve cover, release the oil, with oil cleaning equipment cleaning, troubleshooting.