My Old Dishwasher Runs Like New Again… After Cleaning Out All That Black Gunk!

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Wondering how to clean a clogged dishwasher that has black gunk inside? I’m speaking from experience… because it happened to me.

So here it is 2 years later from the first time our dishwasher drain clogged and I was forced to do a major de-gunking in order to get it running back up to speed — because there was lots of slimy black stuff in the dishwasher.

That was then, this is now:

Today, when I glanced at that dishwasher basket in the far back, I noticed black stuff in the dishwasher. There was lots of black gunk that had built up underneath the basket itself.

There was so much black stuff in there that you could actually tell from a distance there was some serious build-up going on in there. No water backing up this time, just lots of slimy black gunk.

Here’s what I did. My process was much the same as last time, with 2 entirely new steps.

So without further ado, here’s how to clean a clogged dishwasher…

How To Clean A Clogged Dishwasher

I decided to get a jump on it before the dishwasher doesn’t drain again like before.

So I armed myself with all of the necessary dishwasher cleaning and de-gunking materials:

  • 1/4-inch Wrench (to unscrew those 2 long screws that hold the dishwasher basket in place)
  • Flashlight (to visually confirm that, upon closer inspection, yes there was some serious black gunk building up underneath that dishwasher basket)
  • Paper towels (lots — to quickly wipe up most of the mess & toss right into the trash)
  • Soft cloth, wet (to leave the dishwasher in pristine clean condition after removing all the black gunk)
  • Turkey baster (to siphon out some of the water that had accumulated up to the rim of the basket/flapper — there wasn’t water on the dishwasher tub floor this time)
  • Mirror (to see way in the back and make sure that I’d removed all of the black gunk)

After I removed the dishwasher basket from the back (the part that keeps large food debris out), I cleaned out all of the black gunk. I’m telling you, this is some thick and slimy stuff!

Then, I put the basket back in place using the steps that I outlined here.

These are the before and after photos:

My 2 New Steps… How To Clean A Clogged Dishwasher

By the looks of things, I’m guessing I’ll have to do this type of dishwasher cleaning every 2 years or so.

I’m also taking a few extra precautions by following these 4 tips for keeping your dishwasher running smoothly for years.

The 2 things that I plan to do regularly from now on are:

#1 – Each time before running the dishwasher, run cold water through the sink garbage disposal for 30 seconds first — to prevent food and debris that’s in your garbage disposal from getting sucked into your dishwasher’s drain line and clogging it.

#2Fill the detergent and the drying-agent dispensers with white vinegar, then run the dishwasher empty on the pots-and-pans cycle — to keep the dishwasher drain lines clean and free-flowing. (Because vinegar is a great de-gunking dishwasher drain cleaner!)

Tip: Some recommend pouring 1 entire gallon of vinegar into the bottom of your dishwasher and letting it sit for 1 hour. This will loosen the most stubborn scum and gunk that has settled in. Then, run the dishwasher on a short cycle with no detergent.

How To Clean A Clogged Dishwasher Before The Water Backs Up

I would strongly recommend that you always keep a step ahead of your dishwasher on the de-gunking process — because it’s 2 to 3 times more effort (and much smellier and messier) if you wait until the water has actually backed up inside your dishwasher and wreaks havoc on your floor!

Take a look at the first photo in this article again — you can barely tell there’s anything wrong.

But if you look at the next picture — you can see all of the black slime and food stuck to the underside of the dishwasher basket. It was also lining the entire tub of the dishwasher underneath the basket. Ugh!

A Tip From The Family Handyman:

This photo by Bill Zuehlke at The Family Handyman magazine shows the dishwasher float switch and the dishwasher filter.
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When your dishwasher no longer gets your dishes clean, a food-filled filter is most often to blame. If it’s clogged, water can’t make it to the spray arms to clean the dishes in the top rack. The fix takes 2 minutes… Simply pull out the lower rack and remove the filter cover inside the dishwasher. Then, use a wet vacuum to clean off the screen. While you’re there, slide the nearby float switch up and down. If it’s jammed with mac and cheese, you won’t get any water. If the cover sticks, jiggle it up and down and clean it with water.


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22 thoughts on “My Old Dishwasher Runs Like New Again… After Cleaning Out All That Black Gunk!”

  1. My problem wasn’t the filter, but the air gap where the drain hose from the dishwasher connects to the hose to the disposal.

    I found a big chunk of shrimp tails, crab shells, and hair in it — so nasty!

    The passage for that water is as narrow as a couple millimeters at the narrowest, so any solid stuff that gets past the basket filter can definitely cause problems.

    Here’s a useful explanation if you don’t know which bit the air gap is: https://www.popularmechanics.com/how_to_central/home_clinic/1275531.html

    Reply
  2. wow…the inside of your machine looks JUST like the one I am dealing with…yep- a GE. I have bailed the water but not quite to the extent you have, I have used the last of my vinegar (ughhhh the stuff that floated up) and poured some boiling water. My gunk is more white than black… I wonder what gunk colour can tell you! Now I have put the filter basket in the top rack and I am currently running the machine with dishwasher detegent…and THEN I find your post .
    So if the machine is still not draining…I guess I’ll have to clean it a bit more thoroughly and then if that fails…call the plumber cause I’m not doing pipes. There has to be a line drawn somewheer!!! Putting LARGE bottle of vinegar on the shopping list now.

    Reply
  3. Well I was having the same problem with water not draining. I went to remove the drainage basket but mine have no screws. So I took a screw driver and just inserted into the holes to make sure there were no clogs. Some of the holes were clogged. Then, since there were still some water remaining. I used a plastic cup like a plunger. Seems like its working. I guess the final verdict will be when I run a full cycle of plain water.

    Reply
  4. You saved my bacon, friend! My husband was NOT thrilled that I had clogged the garbage disposal and dishwasher. I followed your directions while he was at work and am running the test cycle now. THANK YOU!

    Reply
  5. This was the best advice ever. Just fixed my dishwasher. It was not emptying. Did all the above steps. Put it on the rinse cycle to check and water is not emptying properly. Excellent diagnosis and repair suggestions.

    Reply
  6. this was great. thank you. i am running it now on a short cycle to see if it worked. i did find some plastic and glass. i did not have a mirror so i used a toothbrush on the opening that i couldn’t see. if this does not work i will do the vinegar.

    Reply
  7. Whoever posted this fix thank you. I did exactly what you recomended and it worked! Thanks I thought I might have to replace a dishwasher that I cant afford to replace. Cheers

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  8. Cool. I have the same crappy dishwasher, and had to boil off the gunk that was under the plastic screen. We’ll see if the baking-soda-and-vinegar fix works again or if we have to call the maintenance man.

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  9. I have to thank you for saving us $ 100 just to get a diagnostic on the dishwasher. I found your page and did the vinegar step and my dishwasher stopped jumping to speed cycle! Thank you 🙂

    Reply
  10. Uhh, it’s easier (and less gross) to siphon without sucking. Fill the tubing/hose with tap water then hold a thumb over each end. Put one end under the sitting water, put the other end (lower) into a basin. Release both thumbs and sitting water should siphon out.

    Reply
  11. Your dishwasher’s drain line should not run into your garbage disposal. In every area that I have lived it’s against code to do so. Code or not, it’s just a bad practice. If your sink’s drain plugs up, all of that nasty crap will flow back into your dishwasher.

    Reply
    • The dishwasher is supposed to go to the disposal, just not directly. It’s supposed to go thru a device called an “air gap” which keeps it from siphoning, or stuff from the disposal going back to the dishwasher. Also the air gap can become clogged as well. There is a very easy way to clean it. Just take a roll of paper towels and pull off the top of the air gap (usually just lift straight up.) Then put the tube of the roll of paper towels down over the air gap and make a seal by pushing down firmly on the roll of paper towels to the kitchen sink. A full roll is usually too big to work, about a half roll works best. Then put your mouth to the other end of the tube of the paper towels and blow as hard as you can. If there is a blockage you’ll feel the resistance and then it opening up. You might have to do this a few times after each running of the dishwasher till you have the system free of debris.

      Reply
  12. Just FYI, (because someone asked) white gunk is usually grease/oils. Black gunk is mold/bacteria/algae from the decomposing food.

    Reply
  13. The other day a co-worker gave my husband a portable dishwasher. This was awesome because “Hello there” I am this family’s dishwasher lol. What is not so awesome….the nastiness of this dishwasher. We had no idea until the guy brought it over. I am crossing my fingers that thoroughly cleaning it will be easier than getting rid of it. Gunk in it (like what you described in yours) but I am willing to bet anything that you have seen not anything grosser than our new dishwasher. There was fuzzy mold and (I’m not kidding by this next part at all!) chicken bones. My guess is someone thought they could cook a chicken in the dishwasher. Plus a few cigarette butts when I was down in there deep cleaning. Finding your blog through Pinterest, a YouTube video how to on taking apart the inside of the dishwasher and a few more Pinterest and Google searches, I’m really hoping in one more hour this thing will be clean enough to wash my dishes in.

    Reply
  14. If you’re having dishwasher drain issues (stuff left in the tub) get a mop bucket and unclamp the hose under the sink. You will probably find gunk in there which you can get out with a “brush” made from a coat hanger (bend an oval shape with no sharp points). You can also run the dishwasher with pine sol so it drains in the (5gal) bucket.

    Reply
  15. That dishwasher looks like the Hotpoint dishwasher I had at my current apartment. I cleaned that thing and next month exactly 30 days from when It was as white as the plastic I had STILL black gunk. I opened the door when the load was fully going and the water doesn’t even come up all the way to the trap. That filter there sucks and because it’s Hotpoint it too sucks! only apartments get cheap crap like that. I complained to the manager who just gave me a bottle of dishwasher cleaner that didn’t do shit either. One day I noticed my Jet dry solution wasn’t draining like it should… I though that was odd So I took the entire assembly apart, the seals around the side of the dishwasher was black mold. even behind the unit. The air drain that keeps moister from building up has caked on mold. I demanded at this point to give me a proper dishwasher that wasn’t toxic to my families health. The guy came over, looked at it and just ran a load with another bottle of dishwasher cleaner, told me that it works fine so they are not going to replace it. I went down to Home Depot. I purchased a new dishwasher that had all Stainless Steel, a food disposal a high temp sanitizer. $429. just needed a $25 hose kit which I forgot to get. had to come back. Installed it myself. I wrapped the old dishwasher in plastic and left the dishwasher in front of the managers office with about 20 pictures of the mold over the last few months. From there I got a call from the owner who apologized to me and credited the amount of the dishwasher off my next month’s rent. Better that or take them to court for a few thousands I suppose. Now I don’t have a problem. I can stand an old washer/dryer and crappy electric stove but my dishes which I expect to be clean and sanitary I won’t put up with that shit!

    Reply

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