3D measuring industrial endoscopes can penetrate into the cylinder block to detect the wear amount of the piston crown, the deviation of cylinder wall finish, and the dimensional accuracy of air passages and oil passages. Using three - dimensional data, it can be determined whether they meet assembly standards, avoiding power loss or oil leakage. During maintenance, without disassembly, it can directly measure the thickness of carbon deposits and the wear of valve sealing surfaces, formulating precise plans to reduce component replacement costs.