Have problem with some dirty water accumulating in bottom. Removed plastic grill inside bottom and cleaned out pump sump. One small piece of plastic removed from pump grill. No change in operation. There is no air gap, but waste hose loops above garbage disposal. Garbage disposal is new and works (drains fine). I looked at parts list for this pump assembly but found no check valve. Is there an aftermarket check valve that will fit the discharge hose where the hose connects to the pump? The dishwasher seems to work fine, just appears to have some waste water running back down the hose when it shuts down.
Answer Charles, You need to check and make sure the dishwasher and drain hose are properly installed, no twists kinks ,etc. then check to make sure there aren't any debris in the drain hose. Disconnect the drain hose from the disposal, start the dishwasher and let it run a minute or two, put the end of the drain hose in a large bucket, then drain the dishwasher, this will usually clear anything floating in the hose. Then check the drain solenoid WD21X802 and linkage to make sure it is not binding or causing tension on the lever, this would allow the internal flapper to remain open, and water to back flush into the tub. We are not aware of a "universal" dishwasher drain hose check valve, but you may want to check at the local hardware store or home improvement center.