Packing nuts have either rubber or plastic packing inside the threads of the nut to help provide a leakproof seal. The material inside the threads depends on the size of the nut and the application. Packing nuts are typically found on faucets around the home, although there are other applications such as propeller shafts. Loosening a stuck packing nut is a bit different than a standard nut. You should avoid using heat to loosen a packing nut. The packing material inside begins to melt or distort from the high temperature.
Place a 6-point socket wrench over the packing nut if working on single packing nut with no locking nut. The 6-point socket grips the nut more securely than a wrench or 12-point socket. Hold the top of the socket wrench over the nut with one hand and turn the handle counterclockwise.
Slide a breaker bar over the handle of the socket wrench if the nut does not loosen. A breaker bar is a hollow metal tube that will fit over the socket wrench handle and should be twice as long as the socket wrench handle to add more leverage. Use the breaker bar as an extended handle of the socket wrench.
Place the tip of a chisel or centre punch on top of the packing nut. Strike the top of the chisel or centre punch with a hammer twice. This usually knocks the sediment holding the nut loose enough to begin turning the nut.
Loosen packing nuts on propellers with special packing nut wrenches. These are specifically designed to fit around the confined spaces for the packing nut and the locknut. Hold one wrench on the outer locknut and one on the packing nut. Turn the outer locknut counterclockwise. If necessary, tap the handle of the wrench to start the nut turning. Once the locknut turns two revolutions, the packing nut will turn.
Packing nut wrenches are available at home improvement centres and outboard dealers.