Oil seal assembly and mounting method thereof

The invention provides an oil seal assembly and a mounting method thereof, and belongs to the technical field of water injection equipment. A tappet is sleeved with an oil seal box body, and the end, provided with an inner flange, of the oil seal box body is installed on a crankcase. An oil seal pressing cap is arranged at one end of the oil seal box body, a framework oil seal is coaxially installed in the oil seal box body and located between the oil seal pressing cap and the inner flange, and one end of the framework oil seal bears internal pressure from the interior of the crankcase. The inner diameter of the end, close to the framework oil seal, of the oil seal pressing cap is larger than that of the end, away from the framework oil seal, of the oil seal pressing cap. A closed space is defined by the oil seal pressing cap, the oil seal box body and the framework oil seal. A pressing cap oil guide hole at the large-inner-diameter end of the oil seal pressing cap and a first box body oil guide hole in the o