Abstract: Injection molding apparatus wherein a heated nozzle extends into an opening in a cooled mold. The nozzle has a locating and sealing ring made of a deformable material. After installation the locating and sealing ring contacts an inwardly tapered surface of the mold or an insert seated in the mold extending around the opening. When the nozzle is heated to the operating temperature, thermal expansion drives the locating and sealing ring forwardly into greater contact against the inwardly tapered surface. In one embodiment, the locating and sealing ring is near the front of the nozzle, and the nozzle also has a rear locating flange. During insertion of the nozzle into place in the opening and thermal expansion of the nozzle, the rear locating flange first comes into contact with an inwardly tapered shoulder extending around the opening which prealigns the nozzle.