There is a plastic bushing which centers the impeller on the shaft. The impeller never sticks to the shaft, but the drive key will stick in the impeller. On current design, we use a key with a tee cross section which rests on a flat, milled to the end of the driveshaft, including the thread.The impeller with the key in it will slide off the end of the shaft. Under torque, the key cams itself against the flat on the shaft. It is usually necessary to bump the impeller counter clockwise on the shaft until the keyway is perpendicular to the flat, (centered over the flat). Two 3/4 x 1 1/2 x 12 inch pine levers against the housing flange will slide the impeller off. On earlier designs where the keyway in the shaft traps the key, and it is also stuck in the impeller, it is necessary to drill out the brass key to free the impeller. Use a 3/16 drill in the large series and a 1/8 drill on the medium and small series.
Posted in: Maintenance & Ownership