Jim H for Model Number DU4000XR1 Is the check valve, 675238, the component that keeps outgoing (dirty) water from coming back into the tub? I have seen other units which use something called "piston and nut" for this function ... but do not see such an item listed for the Whirlpool machine.
Answer Jim, Yes, the 675238 / 675238 Check Valve assembly is designed to keep drain water from entering the dishwasher tub, in the event of a drain problem. The "piston and nut" is used by a different manufacturer and serves the same purpose. All manufacturers now have some type of "check valve" on the drain system of dishwashers. Read More... Answered by AppliancePartsPros.com | Tuesday, March 10, 2015