Gear oil pump with adjustable meshing clearance and installation method of gear oil pump

The invention provides a gear oil pump with adjustable meshing clearance and an installation method of the gear oil pump, and relates to the technical field of oil pumps. The gear oil pump with adjustable meshing clearance comprises a pump body, an oil pump transmission gear and a crankshaft transmission gear. The oil pump transmission gear is installed on an oil pump drive shaft, and the crankshaft drive gear is installed on an engine crankshaft. An oil pump mounting and positioning sleeve hole is formed in the mounting surface of the pump body, and a mounting and positioning sleeve is assembled in an oil pump mounting and positioning sleeve hole in a clearance manner. The oil pump mounting and positioning sleeve hole is a stepped hole with diameter becoming smaller from outside to inside, the stepped hole comprises a large hole and a small hole communicating with the large hole, the diameter of the large hole is 8 mm, depth of the large hole is 4 mm, the gap between the mounting andpositioning sleeve and th