Knocking, Hammering, or Thumping Noises:
Typically, a knocking or thumping noise will only occur during agitation/wash and spin portions of the cycle.
In What Cycle is the Knocking or Thumping Noise Occurring?
There will be a knocking/thumping noise as the drive system shifts from agitation mode to spin mode or vise versa. These sounds are part of the normal washer operation.
Do not overload the machine, and do not wash one item by itself. If you wash a bulky item, such as a blanket, use towels as counterweight to even the load.
With an off balance load, it is possible for the tub to hit the cabinet of the washer. This may cause a knocking/thumping sound. Be sure that you are loading clothing evenly around the agitator or wash plate. Also verify that the washer is level front to back, side to side, and that all four feet are touching the floor with the locking nuts tightened.
Some knocking/thumping sounds are part of the normal operation of the washing machine. You may hear different sounds depending on which cycle the noise is occurring in.
Household plumbing/water lines thumping or hammering:
Sometimes certain sounds are caused by water running through your house water lines, especially when using hot water. Your water lines (pipes) may expand and contract, causing a thumping or hammering sound. This is normal and is not caused by the washer. Contact a plumber to see if they may be able to correct some of this noise.