Whirlpool Gold Dishwasher makes a very loud noise when running

Hi you probably have something in the sump drain assembly (this is a common problem with Nautilus DW's) there's a screen on the right side of the spray arm with 2 screws remove them and take screen off use your fingers to probe the cavity be careful it could be glass.

If it does not correct the problem

!.You may have an electric pump . and it could be pump without water . so i would say a bad pump....but since you say everything is draining well...then I doubt the later...HOWEVER...you did say it ran forever...which is absolutely typical of something in the sump...drain area...which will make the drain cycle run because it believes something to be in the drain.....there is also a check valve...that the drain hose attaches to...(it comes right off of the motor assembly) when you take the hose off there is a check valve that screws into the hose or the motor assembly...(it could have debris in the hose that is not being drained all the way out and it is finding it's way back to the check valve) ...shop-vac the drain line...or the valve is screwed into the motor assembly where the hose disconnects...and there may be something stuck in the valve...unscrew it and check that the valve is in good shape...and free of debris......reassemble...and run through cycle....if you need any of these parts...or any specific instructions on replacement of these parts...here is a great site...Quality for less and quick delivery.

http://www.appliancepartspros.com

I hope this helps...I believe it will....Good luck and good day....thank you for your rating my effort....The Fang.