Pressure washers with direct drive water pumps are a popular tool with both the homeowner and the professional contractor. These units are economical, well-designed machines with few moving parts. Pump replacement or repair is possible with only a few tools and limited know-how, and can be a good way to save on repair bills. Removing the pump from your pressure washer usually involves removing only four bolts. Check your particular model's manual for the pump diagrams and location of the mounting bolts.
Disconnect all the hoses from the pressure washer and place on a firm, level surface. On electric models, make sure the machine is unplugged, and disconnect the spark plug wire from the spark plug on gas-powered units.
Spray penetrating oil along the top groove of the pump flange and along the joint where the flange connects to the engine.
Remove the mounting bolts and washers holding the pump assembly to the engine using the correct size socket.
Loosen the set screw on the drive shaft using an Allen wrench. To align the set screw with the access hole in the drive shaft cover, gently pull the starting cord an inch or two to rotate the shaft.
Remove the pump from the crankshaft and the engine face. If the pump will not easily slide off the crankshaft, take a large flathead screwdriver and insert between the slots on either side of the mounting flange and pry the pump loose, alternating sides. Do not use excessive force.
Insert two full threaded screws into the special holes in the pump flange near the mounting bolts if the pump still has not come free. These holes will allow the screws to be threaded only in the flange and to push against the engine face, exerting force towards the pump. Thread the screws in until they make contact with the gas engine adapter plate or the electric motor.
Thread the screws in an alternating pattern until the pump separates from the engine drive shaft. Do not apply excessive force--only use reasonable pressure and torque.