Dishwasher leaves food particles on top rack


Old 05-14-04, 07:57 PM
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Question Dishwasher leaves food particles on top rack

I have a White-Westinghouse dishwasher model MDB124BFS2. I think it is actually made by Frigidaire.

The problem is that it leaves food particles on the dishes and glasses on the top rack.

I have checked the top sprayer arm during the rinse cycle and found it hardly ever changes position. When I open the door to try to catch the sprayer arm turning, it remains in the same position with no water in it.

I have balanced a little cup on top of the top sprayer arm funnel to catch the rinse water, but it remains empty.

So I don't think the rinse water is making it to the top arm.

I have opened the impeller area, and made sure it is clean. I have found the tube that leads from the bottom area up the side and to the top sprayer arm. I have passed a length of bicycle brake cable through that tube, so I know it is not obstructed.

What I wonder about most is the little check ball that rides on a little ramp and blocks off this tube in the impeller housing. I can't understand how the water flow would ever allow this ball to get out of the way so the water could travel up the tube to the sprayer arm.

Anyone know what I should look for next? I am completely out of things to try next.

Thanks in advance.
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Old 05-15-04, 08:58 AM
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I have not been around these for service... But I know they use a ball to "cycle" the top and bottom wash arm back and forth... I am guessing they may have another set of ball check valve some where else.
Old 05-15-04, 11:08 AM
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Thanks for the insight Jay11J.

The ball is sitting at the bottom of a ramp and blocking the upper spray arm tube. At the top end of this ramp, there is another hole of equal diameter, so it sure looks like the ball is supposed to be able to go up and down the ramp to block off each hole in turn.

But it sure beats me what would make the ball ride up and down the ramp to change position! Seems to me the water flow would always drive it against the lower hole and block off the top sprayer arm.

There must be more going on that I haven't figured out yet. I wonder if there may be an electrical switch that somehow changes it back and forth. Maybe that could be faulty.

Any other ideas anybody?
Old 05-15-04, 11:37 AM
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Thought I should mention it the diswasher goes by the name of White-Westinghouse QuietClean I.
Old 05-15-04, 06:47 PM
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Lightbulb Alternate Possibility

Hello: LifelongLearner

May not have anything to do with the check ball, etc. Just may be the pump and or the impeller in the pump housing. May have a restriction or the pump is defective. Not allowing enough water volume and or pressure.

Just a few additional possibilities.

"Thinking Out Of The Box"
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Old 05-16-04, 12:43 AM
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Wiring diagram found

I went to and put in MDB124BFS2.

Selected wiring diagram, and got this link:

There is a short operational description in the wiring diagram. I've learned that the upper spray arm does not even come on during the first half of the cycle, which is probably when I was checking. No wonder I never saw it turning! More detective work required.

It doesn't say how the water is redirected between the lower and upper spray arm, except to say that it is done by short pauses of the motor. Still don't know how.

The wiring diagram includes a timer switching diagram. It shows one component that might control the water switching between the arms. The component is called "pump" and I can't figure out what that means or what its function would be. I don't think it is the pump motor because the motor has its own line in the switching diagram.

Anyone know what "pump sub. int." means?

Thanks again for any help.
Old 05-31-04, 05:41 PM
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As Sharp Advice said, it might be something else.

Turned out to be the impeller whose blades had been shaved down by a piece of chipped ceramic. Got a new impeller for $10 and it's working great.

The check ball moves back and forth between inlets by water action. A small bypass hole allows water to build in a column. When the pumps stops for a moment, this water drives the ball to the other hole, and the pump starts again then. That's how it cycles back and forth.
Old 06-01-04, 11:48 AM
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Hello: LifelongLearner

Thanks for posting the updated information which resolved the problem.
Sharing, we all learn more.

Glad to know I was able to provide some help and you where able to do it yourself fix the problem too.

Sometimes..."Thinking Out Of The Box" is a worth while benefit...

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Old 11-14-04, 04:11 PM
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I had a similar problem with a GE and now I have it with a Maytag. The upper spray arm does not turn although some water comes out of it. The dishes in the upper rack do not clean as well as they used to. This is especially true of dishes around the outside of the rack. It used to be that a plastic cup on the upper rack would often flip over from the force of the spray from below. Now the plastic cups on either rack never move. I checked the water level and it seems OK; it covers the heater and if I throw in an extra litre of water the dishes do not get cleaner. I cleaned the spray arms and the screen around the pump intake but nothing improved. The spray arms do not look cracked and the impeller looks like new. I replaced the o-ring around the pump impeller housing but performance did not improve. The motor still sounds like it is running fine. The noise of water hitting the inside of the dishwasher is not as strong as it was when it was new but if I open the door a crack and hold the door switch so the dishwasher starts, lots of water sprays out across the room. I was going to try replacing the spray arms. Perhaps I should replace the impeller.
Old 09-23-05, 03:06 PM
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I bought a Frigidaire dishwasher because it had an upper wash arm. But the upper arm didnt work when I first installed the dishwasher. Cups and glasses werent clean, and they had bits of food in them when it was done washing.

I was pretty pissed about it until I read LifelongLearner's post about the check ball, and it got me to thinking about how it all worked. So, I re-read the installation manual. Turns out I missed something because the manual wasnt clear:

The dishwasher has to be level to work right. And to be level, the door has to be parallel to the floor when its open. I left the four adjustment legs screwed all the way up when I took it out of the box thinking that would be level, but the door was angled upwards when open, rather than laying flat as it showed in the manual.

I had to screw down the rear legs about 1.5 inches each to get it level. Now it works great!
Old 01-01-06, 12:42 PM
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I had a similar problem. The dishwasher was making a loud whining noise during pump operation. Items in top rack did not get clean. The top arm not moving when door was opened during operation. I thought the motor was going bad and thought of buying a new dishwasher. After reading this post I removed the verticle spray nozzle,discovered a wadded up drink straw blocking the ball from moving. After removing the straw and replacing the nozzle the noise is gone and all is well.
Thanks, Dave

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