Dishwasher: Why won't my dishwasher drain?

Replace the dishwasher drain pump if it's cracked or damaged, or if the drain pump doesn't pump out water. Before replacing, check the drain path (drain hose, sink drain and sump) to make sure it's not blocked. If the drain path is clear and water doesn't pump out, the drain pump has failed. Replace the drain pump if it won't run even though it's getting run voltage from the timer or control board.

The drain path (sump, pump, drain hose, air gap if installed and sink drain) can sometimes become clogged with debris or grease. In this situation, the drain pump will run but the water won't be evacuated. The drain path will need to examined and cleared to fix this type of dishwasher problem. If the drain line is damaged or cannot be cleared, then it will need to be replaced.

Replace the drain line--also called the drain hose--if it develops a hole or tear. Holes in the drain hose cause the dishwasher to leak, especially when the dishwasher is draining.

The electronic control board runs all dishwasher functions. If the electronic control board is getting voltage, but not operating properly, it should be replaced.

The timer controls the electro-mechanical components in the dishwasher such as the wash pump, drain pump, inlet water valve and heating element. The timer also advances the control knob on the control panel. Replace the timer if it fails to start and stop the components properly or fails to advance the control knob.

Most drain systems in the dishwashers have a check valve that prevents the drain water from backing up or siphoning back into the sump of the dishwasher after the normal drain process is completed. If the dishwasher isn't draining properly, or drain water is backing up into the sump after the drain process, then you will need to clear or replace the check valve.

A kernel of popcorn or a similar foreign object can drop into the chopper blade area of the dishwasher, causing a loud grinding noise when the pump runs. Remove the lower spray arm and the upper part of the dishwasher sump to access and clear debris from the chopper blade area. If the chopper blade is damaged, replace it.

Some dishwashers have a portion of the circulation pump assembly that can be accessed and repaired from inside the dishwasher tub (from the top of the circulation pump assembly). A clog, a foreign object or a failed seal can prevent the water from flowing to the spray arms. A clog or failed check valve can prevent the dishwasher from draining. Remove the lower spray arm and the top of the sump to inspect the upper circulation pump when spray is weak or the dishwasher won't drain. Clear any clogs and replace any damaged parts to restore water flow to the spray arms or drain pump.

Several situations can require the replacing the circulation pump and motor assembly in a dishwasher. If the motor on the circulation pump fails, then the dishwasher pump won't run at all. Sometimes the motor runs but doesn't generate water pressure through the spray arms, because the damaged impeller or pump housing is damaged. The pump housing and/or the seals could also deteriorate or become damaged, causing the dishwasher to leak. Problems inside the pump and motor assembly can create abnormal noises in the dishwasher. In all these situations, the pump and motor usually must be replaced.