Maytag dishwasher leaves black spots all over insides of cups/mugs on top shelf

I cant understand why my Maytag dishwasher leaves black spots all over insi des of cups/mugs/glasses on top shelf.
The spray arms constantly became blocked but even when I cleaned them out, the black bits persist! Cleaning out the main filter doesn't assist eithe r. I have torn down the whole area above the main pump assembly (But neithe r are filled with black material)
It often looks like black powder baked into the enamel during the drying cy cle but surely enough water is swilled around the unit while it is running, - and the dirty water drained out early in the cycle to clean out black p ieces from the water swilling around the unit during later water cycles?
Has anyone had this problem and identified what causes it?
Weak pump weak - so no water getting through to the top of the machine? (P ump sounds OK)
Blocked drain so the black pieces dont drain out with the water? (draining SEEMS to be OK and all water seems to drain out at the correct rate)
Blocked input or defective water level switch so not enough water gets into the machine to do much to the top shelf?
2 cups of white vinegar cycles didnt help either, and afresh never does
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On Wednesday, March 13, 2019 at 5:27:18 PM UTC-4, DManzaluni wrote:

sides of cups/mugs/glasses on top shelf.

, the black bits persist! Cleaning out the main filter doesn't assist eit her. I have torn down the whole area above the main pump assembly (But neit her are filled with black material)

cycle but surely enough water is swilled around the unit while it is runnin g, - and the dirty water drained out early in the cycle to clean out black pieces from the water swilling around the unit during later water cycles?

(Pump sounds OK)

g SEEMS to be OK and all water seems to drain out at the correct rate)

to the machine to do much to the top shelf?

What does this stuff look like? Is it possible the pump impeller or simila r is disintegrating? If no black stuff is going in, then it has to be comi ng from somewhere.
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On 3/13/2019 5:27 PM, DManzaluni wrote:

Do you have problems elsewhere? Have you tried draining the hot water tank to see if there are minerals built up in there? Are you using some cheap detergent?
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On Wednesday, March 13, 2019 at 6:47:25 PM UTC-4, Ed Pawlowski wrote:

insides of cups/mugs/glasses on top shelf.

ut, the black bits persist! Cleaning out the main filter doesn't assist e ither. I have torn down the whole area above the main pump assembly (But ne ither are filled with black material)

g cycle but surely enough water is swilled around the unit while it is runn ing, - and the dirty water drained out early in the cycle to clean out bla ck pieces from the water swilling around the unit during later water cycles ?

? (Pump sounds OK)

ing SEEMS to be OK and all water seems to drain out at the correct rate)

into the machine to do much to the top shelf?

And what's the history, how old is it? Did it work fine for years and this is a new problem? He said the spray arms are constantly blocked too, which isn't right.
These things are quirky. The ge here usually works fine, but every couple o f years, suddenly dishes come out dirty. Rarely have I found a cause. Migh t be one opening in an arm blocked, but can't account for stuff on both lev els not getting cleaned. Like the poster, I've taken out the screen, checke d, cleaned it all, they still come out dirty. Then after a few more uses, s uddenly back to normal again.
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When I got that with my original dishwasher, it turned out to be that it occasionally had a brain fart and didn’t do the wash cycle because it decided that it hadn't got enough water to be safe for heating it to the full wash temp. I only noticed why it did occasionally do that after I had retired and noticed that it finished quicker than normal with those runs that didn’t wash the dishes. I used to put it on just before I headed out to work because it was a bit noisy.
Eventually it scaled up the input solenoid badly enough so that it wouldn’t wash at all.
The current Bosch is much better at indicating that its got a water problem because it has a proper set of lights that indicates those common problems. The original dishwasher was entirely mechanical and had no way to indicate a problem or even any way to decide what the problem was. It just skipped to the end when it didn’t get enough water to heat.

I never had mine fail twice in a row, even if I did nothing.
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No, no other problems and I dont think it is a disintegrating impeller, the dishwasher is only about ten years old. It might be stuff coming off my teflon sheet. But it remains swilling around the machine cycles after I have stopped cleaning the sheet,
So I am wondering why the cycles dont simply drain the powder away during a first wash, not to mention the second wash
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There doesn't seem to be water making its way through to the upper level tray
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On Wednesday, March 13, 2019 at 7:13:25 PM UTC-4, DManzaluni wrote:

tray
Can you follow the path of the plumbing inside and it looks OK? On mine the re is piping from the bottom up to the top and the arm under the top basket plugs into the piping. Mine the arms come off via one bolt so you can insp ect and clean, make sure the holes are really open. I've used the air compr essor to blow mine out.
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More evidence of a blockage in the pipe going to the top spray arm.
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Do you wash filthy baking pans etc in the dishwasher ?
That’s the only black stuff I see much of on what I put in the dishwasher and not all dishwashers get all that off in the first or second wash and could be the problem if the filter or pump is the problem.
I'd try a test run with clean cups in both the top and bottom trays and see if you get the black stuff on the ones in the bottom rack. If you don’t, it’s a problem with the top spray system, maybe a blockage back in the feed to the top arm. And it may be that the black stuff is that blockage coming to bits now.
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On 3/13/2019 7:09 PM, DManzaluni wrote:

Now the rest of the story? What Teflon sheet? Can you see disintegration?
If it is blocking the spray arms there is not enough water to wash it away. It is also in inorganic material that does not react to the detergents very well.
I'd clean the machine well and ditch the Teflon sheet or wash it by hand. You may have to dry the inside and vacuum the particles out.
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No, I don't think this is relevant as the problem occurs numerous cycles af ter I have left a teflon sheet in to wash. And I did dissemble the whole upper arm but the problem persisted under circumstances where I thought the black speckles/powder should have been cleaned off during an initial cycle .
Interestingly, whereas the black stuff is left inside cups/mugs, the stuff which blocks the upper arm holes is white or whiter than the deposits. Mean ing cereal particles? Meaning the impeller isn't getting rid of these parti cles which remain so large that they block the arms?
Curiously, the black particles are ONLY in the cups/mugs! They don't manife st themselves at all within any other parts of the dishwasher.
I am beginning to lean towards the disastrous implication: That the pump is not pumping enough water around the machine at all and certainly isnt pump ing strongly enough to push water into cavities such as cups/mugs?
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Does/can a weak pump sound normal?
If it IS the pump, is the problem terminal?
Is there any way of replacing or repairing a pump economically?
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On 3/14/2019 10:16 AM, DManzaluni wrote:

The machine is 10 years old. Replacing the pump will probably be 30% to 50% the cost of a new machine. I'd consider just replacing it and be done.
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On Thursday, March 14, 2019 at 10:29:41 AM UTC-4, Ed Pawlowski wrote:

Depends on who does the replacing. If you DIY, it's just the cost of the pump which he can find online. But even then, if the pump is say $40, and you're not sure it's the real problem, not sure it's worth it on a ten year old DW. If you get one for $250, it's like paying $25 a year for the use of it over ten years.
Whatever that black stuff is, it could just be that it's some really nasty stuff, just small enough, just sticky enough, that it's going to be there until it all works itself out. Unless something is deteriorating inside the works and that's the source. If it's so bad that it's not worth running to clean dishes, I'd just run it over and over, do 6 or 10 times and see if it's getting better or worse. I'd also try some extra heat cycles, if it has that option. The commerical cleaners for DWs use citric acid, which you can buy at Walmart in the fruit canning supplies, for a lot less. But I don't think that will do anything with this black stuff.
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It can do. Uncommon tho.
But the lack of enough water thru the upper spray arm may just be a blockage in the feed to that arm.
That’s why I suggested a test run with clean cups in both the upper and lower trays to see if the problem is just seen in the upper tray. If it is, its more likely to be a blockage in the feed to the upper tray than the pump.
But even if it does clean the cups in the bottom tray properly that may still be a weak pump that can deliver and adequate water flow to the bottom spray arm but not to the upper one because the upper one has more pipe leading to its arm.

Nope, you can replace it.

That varys with the dishwasher. The later Bosches have a fully integrated pump and water heater and that thing costs more than a whole new dishwasher as a spare part.
If the problem with the pump is that the impeller has come to bits it may or may not be possible to replace just that depending on the pump. If the impeller has come to bits, it might well still sound fine but might have one of the bits jammed in the pipe going to the upper spray arm blocking the water flow that upper spray arm.
Only way to find out is to test it properly or dismantle.
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On Thursday, March 14, 2019 at 10:11:25 AM UTC-4, DManzaluni wrote:

after I have left a teflon sheet in to wash. And I did dissemble the whol e upper arm but the problem persisted under circumstances where I thought t he black speckles/powder should have been cleaned off during an initial cyc le.

f which blocks the upper arm holes is white or whiter than the deposits. Me aning cereal particles? Meaning the impeller isn't getting rid of these par ticles which remain so large that they block the arms?

fest themselves at all within any other parts of the dishwasher.

is not pumping enough water around the machine at all and certainly isnt pu mping strongly enough to push water into cavities such as cups/mugs?
Assuming the cups don't have black particles in them when you put them in, then when they are there at the end is proof that water is reaching the cup s. Also, if you put a decently dirty cup in, does it come out clean, except fo r the black particles? Then I'd say that's a good indication that the proble m isn't with the water flow. How many cycles have you run now without putti ng anything in that could account for the black stuff? Is it getting better, staying the same or getting worse?
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On Thursday, March 14, 2019 at 10:33:52 AM UTC-4, trader_4 wrote:

s after I have left a teflon sheet in to wash. And I did dissemble the wh ole upper arm but the problem persisted under circumstances where I thought the black speckles/powder should have been cleaned off during an initial c ycle.

uff which blocks the upper arm holes is white or whiter than the deposits. Meaning cereal particles? Meaning the impeller isn't getting rid of these p articles which remain so large that they block the arms?

nifest themselves at all within any other parts of the dishwasher.

p is not pumping enough water around the machine at all and certainly isnt pumping strongly enough to push water into cavities such as cups/mugs?

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Thinking about this more, it's pretty simple to test. Take an range of cup s, small pots, etc with easy to clean stuff on them, to tougher stuff. For easy, dried on tomato sauce would work. For harder, a pot with some cooked on stuff that should still come off. Put that stuff in the top rack where you think water may not be getting to and run it. If it all gets cleaned u p like normal, then you know it's not a water pumping issue.
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On 3/13/19 4:27 PM, DManzaluni wrote:

Suppose you disconnect the washer from the water supply. Connect a hose to the supply and run the water directly into the drain. No idea if it would help but it should at least eliminate one potential problem.
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On Wednesday, March 13, 2019 at 7:17:08 PM UTC-4, Dean Hoffman wrote:

insides of cups/mugs/glasses on top shelf.

ut, the black bits persist! Cleaning out the main filter doesn't assist e ither. I have torn down the whole area above the main pump assembly (But ne ither are filled with black material)

g cycle but surely enough water is swilled around the unit while it is runn ing, - and the dirty water drained out early in the cycle to clean out bla ck pieces from the water swilling around the unit during later water cycles ?

? (Pump sounds OK)

ing SEEMS to be OK and all water seems to drain out at the correct rate)

into the machine to do much to the top shelf?

Wonder what would happen if you put a smartphone in a sealed plastic bag an d tried to video what goes on inside when it runs? Probably would be too b lurry to work.
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