Dishwasher troubleshooting

October 30, 2018 6:35 PM

We know how to use a dishwasher, we've successfully used other dishwashers before — the problem is this dishwasher. We're currently stuck using it as a plate-warmer: unless we hand-wash everything before putting it in, every load comes out with a smattering of dishes still dirty. This is in a rental unit with a very hands-off landlord, so we're strictly in DIY mode. What things should we try before we give up and hand-wash everything?

Since it will probably come up: we're familiar with the theory that says "Prewashing tells the dishwasher to go easy, so for best results, prewash nothing." In our case, running a whole load with zero prewashing gives worse results, not better.

posted by nebulawindphone to Home & Garden (37 answers total)

Sorry if this is super obvious, but do you run the hot tap until the water is already running very hot when you are starting the washer? That's what makes a difference with mine.
posted by CheeseLouise at 6:40 PM on October 30, 2018 [5 favorites]

What model is it?
posted by aramaic at 6:45 PM on October 30, 2018

Is there any pattern to which dishes come out dirty, or is it random? What if the load is very sparse - in an almost empty load, are there still always a few dirty pieces?
posted by batter_my_heart at 6:48 PM on October 30, 2018

What kind of dishwasher is it? How old is it? Do you have hard water?

My dishwasher isn't great, but it's old and we have very hard water, so I raise the water heater temperature, and run the tap to get the water hot, and I don't over fill. I use good detergent, the old-fashioned rinse agents that you tie on the top rack, and boosters like citric acid to help with spotting. They all help.
posted by answergrape at 6:51 PM on October 30, 2018 [2 favorites]

Also, empty the waste traps every time. You might want to inspect them to see if they aren't clearing as they should.
posted by answergrape at 6:53 PM on October 30, 2018 [6 favorites]

(1) It might have a food grinder in the bottom and the food grinder might be clogged or even broken, so food just sticks around in the rinse water.

(2) If you have a garbage disposal, try running the garbage disposal right before you run the dishwasher.

(3) Open it quick during the cycle and make sure that water is actually coming out of all the jets. We had a dishwasher that got clogged jets due to hard water.
posted by muddgirl at 6:55 PM on October 30, 2018 [2 favorites]

Response by poster: It's a Bosch something — I don't see a model name or model number anywhere. I believe it's pretty new.

We have soft water.

The problem is with food crud stuck to the plates, not with spots or streaks.

I don't see a pattern to which plates come out dirty.

I haven't tried running a mostly-empty load — is there something I should look for when I do?
posted by nebulawindphone at 6:57 PM on October 30, 2018

Yeah, I've had the hand's off landlord and what I do is call the local appliance repairman and bill it to my landlord. It seems to get fixed right away then.
posted by Marie Mon Dieu at 6:58 PM on October 30, 2018 [1 favorite]

I JUST did this two days ago... It sounds like the food grinder is clogged. The video here shows you what to do.

Good luck!
posted by bird internet at 6:59 PM on October 30, 2018 [2 favorites]

Model not that important, they're all pretty much the same...
posted by bird internet at 7:00 PM on October 30, 2018

We have a newish Bosch too and it doesn't really like much food being left on the plates - I've found that it much prefers it if I rinse things sufficiently to get the food off at least - it hates dried on cereal in bowls especially (children, I'm looking at you). Checking/cleaning the trap is good advice, as is running a dishwasher cleaner through it - the kind that you leave in and run on an empty load.
posted by Chairboy at 7:02 PM on October 30, 2018

My friend recently food out that her dishwasher in her apartment NEVER HAD THE WATER TURNED ON. It was a new place and presumably they turned off the water to fix something(??) and never turned it back on. It took her about 8montha to find out because she always prewashed/rinsed so well.
posted by raccoon409 at 7:15 PM on October 30, 2018 [1 favorite]

Is there gunk (food debris) in the bottom of the machine? That would indicate a clogged grinder or drain line, which usually isn't hard to fix.
posted by metasarah at 7:20 PM on October 30, 2018

Seconding running the garbage disposal before the dishwasher. You can also look for a hose running from the dishwasher to the drain of the sink and try to attach that hose as high as possible. We had food going from the disposal to the dishwasher in a cheep (Home Depot) Bosch dishwasher.
posted by shothotbot at 7:24 PM on October 30, 2018

Yeah if you're in a rental there's a good chance the waste traps have NEVER been cleaned. Which is something that should be done actually pretty often. In mine there's a mesh trap at the back bottom and over the drain. They come off with a socket wrench. Warning, get gloves. It can be REALLY gross. My drain traps both come off and can be washed. We found broken glass stuck in the bottom of our drain - not from any of our dishes - that also got in the way of draining. Be careful if you're digging around. Then you can wipe up all the edges use vinegar or a cleaning solution and see if it helps.
posted by Crystalinne at 7:26 PM on October 30, 2018 [6 favorites]

Some Bosch dishwashers require the use of dishwasher salt. If you haven’t, try a different detergent, like cascade complete pods.
posted by Kalatraz at 7:38 PM on October 30, 2018

We never got truly clean dishes in our Bosch dishwasher until we switched detergents from the Costco liquid brand to a different brand powder.
posted by pised at 7:59 PM on October 30, 2018

Rinse aid helps with our bosches... but honestly, they are the most overrated appliances ever. I don’t know how they wound up with such a stellar reputation.
posted by slateyness at 8:22 PM on October 30, 2018 [1 favorite]

Bosch owner here. There is no food grinder/disposal on these units, you DO need to scrape or prerinse off any major food particles to get a good cleaning. You should also clean the filter and trap regularly like in this video. Also check that the sprayer arm holes are not clogged with debris.
posted by JoeZydeco at 8:27 PM on October 30, 2018 [4 favorites]

I JUST did this two days ago... It sounds like the food grinder is clogged.

Bosch doesn't have a food grinder. It has a filter at the bottom of the tub that you must clean every couple of weeks.
See this video.

When you remove the filter to clean it, also poke a finger carefully in the opening and use a flashlight to see if anything is stuck in the opening that would block the flow.
posted by JackFlash at 8:28 PM on October 30, 2018 [1 favorite]

Definitely check the trap/filter (with caution- this is a place where broken glass from a previous tenant could hide).

In any city of reasonable size are small appliance repair people who will come to your house and attempt to deal with this- I know you don’t want to deal with your landlord, but if you really really don’t, and nothing here works, and you also have a hundred bucks you can spare, it would be worth it to me at least to pay out of pocket for a fix so I don’t have to do all the damn dishes.
posted by charmedimsure at 9:14 PM on October 30, 2018

Also check that the sprayer arm holes are not clogged with debris.

Seconded. I used a cake fork to dislodge some of the crud in mine and it made a world of difference.
posted by krisjohn at 9:47 PM on October 30, 2018

I had a Bosch at my last place and have one now. Citric acid if your sprayer jets are clogged. Cheap, in bulk, throw a couple tablespoons in per load after a larger dose to clean the funk out post scrubbing as above. You can eat it, so it’s safe to use.
posted by OneSmartMonkey at 11:56 PM on October 30, 2018

honestly, they are the most overrated appliances ever. I don’t know how they wound up with such a stellar reputation.

The first time I ran the Bosch dishwasher we've now had for four years I was super impressed by how quiet it is. On opening it after that very first cleaning cycle, I realized that the main reason it's quiet is that it really doesn't wash things very well.

Things that help a bit include knocking all the loose crud off plates before they're loaded in so it doesn't end up blocking the swing arm jets, and getting religious about cleaning out the sump filter.

But the single most effective thing is always using the hottest cleaning cycle, and not using half-price generic dishwasher powder. The Bosch seems to rely more heavily than most on the sheer caustic chemical power of dishwasher detergent in hot water. All that the jets are really good for is delivering vicious chemicals to the surfaces of the dishes. Physically dislodging undissolved crud off those surfaces seems a bit beyond them.
posted by flabdablet at 1:17 AM on October 31, 2018 [2 favorites]

We also have a Bosch.

When we ran out of dishwasher pods & temporarily switched to powder, nothing we washed came clean. We had the same problem with cheap off-brand pods, so now we only buy Cascade Complete.

If we find things aren't getting clean now, it's always because crud has built up in the filter & drain bit in the bottom. Cleaning those out fixes it every time.
posted by belladonna at 5:21 AM on October 31, 2018

After cleaning trap and sprayer arm holes, fill a cup with vinegar, put it on the top rack, and run a cycle without any other dishes. (I also pour in some extra in the bottom, though I don't know if that helps.) It makes a big difference.
posted by Mr.Know-it-some at 6:57 AM on October 31, 2018 [1 favorite]

We have a Bosch dishwasher that I installed myself, and it's awesome (with the right detergent and with rinse aid, as instructed). People have already mentioned the filter at the bottom and the possibility the drain line is clogged, but the thing that shothotbot said about the routing of the outlet hose is critical. The high routing of that hose acts to prevent backflow both from the dishwasher itself and from anything else that goes through the disposal. That hose should go from the dishwasher up to nearly the level of your counter, and then down to the disposal. It shouldn't loop. It shouldn't go up to the disposal. There's a clamp in the mounting kit that's used to attach it to whatever high point, so if that clamp is missing the hose is probably not really preventing backflow.
posted by fedward at 7:27 AM on October 31, 2018 [1 favorite]

I've never had a dishwasher that actually washed dirty dishes. Never ever. Some (the Bosche and WhirlPool new ones) would wash some dishes, as long as nothing was sticky.
posted by The_Vegetables at 7:48 AM on October 31, 2018

One more thing to check for is the spraying arms thingies being able to rotate freely. If you give them a good shove and they stop within a full rotation they need to be decrudded. On ours they can just be pulled off their hubs, other machines may have a locking cap on the hubs to hold them.
posted by Stoneshop at 8:06 AM on October 31, 2018 [1 favorite]

If you give them a good shove and they stop within a full rotation they need to be decrudded.

Not just crud. I've noticed on mine that there's very little clearance between something large (like a dinner plate) sitting sideways in the rack and the bottom of the sprayer arm above. If I get a bad load, it's usually because something is blocking the arm from rotating.
posted by JoeZydeco at 9:19 AM on October 31, 2018

Another Bosch owner here. As others have said, do clean the filter frequently, but also make sure you are using JetDry or the equivalent rinse-aid. It allows the water to run more freely over the dishes so it should help remove particles (as well as aid in drying).
posted by mcgsa at 9:42 AM on October 31, 2018

"Since it will probably come up: we're familiar with the theory that says "Prewashing tells the dishwasher to go easy, so for best results, prewash nothing." In our case, running a whole load with zero prewashing gives worse results, not better."

Sorry for this tangent, but where on earth would such a faulty theory come from? How would a dishwasher even begin to detect the state of dishes in this way? AFAIK they don't have so much as a weight sensor to see how heavy the load is. IN general, having seen a few videos of the inside of a dishwasher in action, it's kind of a miracle any of them ever clean anything. Often it looks more like dishes skipping through a lawn sprinkler, entirely unlike anything being pressure washed or what have you.
posted by GoblinHoney at 11:15 AM on October 31, 2018

RE: automatic soiled dish sensor:
From GE, not Bosch.
Use only as much water as needed with the new state of the art sensor using laser technology that controls the wash selections by sensing water turbidity and measuring water temperature 100% of the time. It then adjusts the wash time, water temperature, water amount and number of fills for efficient effective wash performance. The sensor will indicate if the water is still soiled and will call for more water to be added or extra cycles as needed.
The Extra Clean sensor is located in the water containment area below the filter. Prior to 2001 the sensor was in a glass tube.

These systems work much better on washing machines than on dishwashers in my opinion.

Water temperature is also a thing many have mentioned. Most operate best at a temperature above 120F, which is a moderately to very hot tap water temperature, but most dishwashers (Bosch included) heat the water themselves, they don't rely on tap temperature.
posted by The_Vegetables at 12:42 PM on October 31, 2018 [1 favorite]

... where on earth would such a faulty theory come from?

I've read that in Consumer Reports, a couple of times. They say there are dirt sensors in dishwashers, and if there isn't enough dirt, the machines act as though the dishes don't need washing. I'm not convinced. I have a Bosch, and find that Costco pods work well.
posted by Kirth Gerson at 2:26 PM on October 31, 2018

If there is a lot of food stuck to the plates then it sounds like not enough water is being sprayed on the dishes, as others have written. This could be a problem with volume or a problem with arm rotation. Check that the arms rotate freely and are clear. Run it without arms fitted to try and blast any junk out, and run some dishwasher cleaner through.

I had a tabletop Bosch that used to suffer with the impellers being eaten away. The impellers were some kind of glass-reinforced plastic injection moulding and after a while (a couple of years) the flow would reduce. If you took the rotor off and ran it, bits of plastic about as big as a fingernail appeared in the cabinet. On that machine, you could just about see the impeller, and certainly feel it with a finger.
posted by StephenB at 2:53 PM on October 31, 2018

One thing I remember from the Bosch user guide is that you're supposed to push the top rack in all the way by hand, and not let closing the door do it. The impeller attached to that rack is fed by plumbing that plugs into a pipe at the back, and the door apparently doesn't push it all the way in.
posted by Kirth Gerson at 3:33 PM on October 31, 2018 [3 favorites]

Bosch owner heren three things lead to this. First and foremost, you MUST use rinse agent(Jet Dry), rinse filter weekly and use Cascade Complete.
posted by nenequesadilla at 3:58 PM on November 5, 2018