Various methods and devices are provided for use in a walking beam compressor used with an oil well pump. In general, an injectable fibrous sealant is provided for use in a stuffing box to form a seal around a piston rod that couples to a walking beam for pumping oil out of the ground. The injectable fibrous sealant can be configured to form a gas tight seal around the piston rod, while allow reciprocal longitudinal movement of the piston rod therethrough. The injectable fibrous sealant is particularly advantageous as it has an extended life, eliminating the need to replace the seal, and repairs can be performed on-site by injecting additional sealant into the stuffing box.