The 'anomalous sounds' in the diesel engine and engine cylinder can be summarized into several types: piston knocking sound, piston pin knocking sound, piston bumping sound, piston bumping sound, piston bumping sound, valve knocking sound, cylinder knocking sound, etc. Then Haixing Generator Company will analyze the true faces of these 'anomalous sounds' for everyone. 1. The impact sound of the piston top and the cylinder head The abnormal sound of the piston top hitting the cylinder head is 'tap' continuous metal hitting sound, which is particularly obvious at high speeds. The abnormal sound source is in the upper part of the cylinder, its sound is solid and powerful, and the cylinder head is vibrating. The main reasons are as follows. (1) The crankshaft bearing, connecting rod bearing and piston pin holes are seriously worn, and the fitting clearance is seriously exceeded. At the moment when the piston stroke changes, the piston hits the cylinder head under the action of inertia force. (2) Because other pistons of similar specifications are accidentally installed when replacing the piston, or fake products, the distance between the center line of the piston pin hole to the top surface of the piston is greater than that of the original piston, causing the piston to bend, making the piston