PURPOSE: To efficiently remove the carbon deposits attached to titled part, by revolving a pressurized-water injection nozzle facing toward the front face of titled part, etc. while injecting water, during the leveling mouthpiece is in an opened state, by means of a specific mechanism.

CONSTITUTION: The horizontal fram 3 on an extruder 1 is equipped with a long-sided frame 6 capable of moving back and forth, while a truck 13 movable in the transverse direction is mounted on the frame 6. Also, while the vertical-moving device of the truck 13 is equipped with an apparatus 25 connected to the pressurized-water feed pipe 26 so that the apparatus 25 can move vertically, a pressurized-water injection nozzle 28 is provided to the front end of the apparatus 25. While the leveling mouthpiece 31 in the coke oven door 30 is in an opened state, the frame 6 is allowed to advance by operating the motor 8 to make the injection nozzle 28 face in close proximity toward the leveling mouthpiece-forming frame 31', followed by revolving said nozzle 28 by operating both motors 23 and 14, along the front face of the mouthpiece 31, the knife edge of the small lid 32, and their peripheries, while feeding pressurized water through the feed pipe 25 to said nozzle 28 to carry out injection, thus accomplishing the objective sweeping.