Dishes still dirty

February 13, 2010 10:19 PM

Our dishwasher makes the dishes dirtier. Can you help?

Cleaning ability has detgeriorated and dishes come out with speckly black bits and also white blotches. The manual is no help. Everything sounds normal when it's running. It's a Kenmore, only a couple years old. Thanks.

posted by hollyanderbody to home & garden (23 answers total)

Clean the debris trap?
posted by fshgrl at 10:40 PM on February 13, 2010

How often do you clean the filter / debris trap? You should do that at least once a month unless you're one of those weird people who washes the dishes before you wash the dishes.
posted by majick at 10:54 PM on February 13, 2010 [1 favorite]

You probably need a Phillips head screw driver, and the courage to remove and clean the basin pickup for the "solids filter" in the tub of your dishwasher.

A lot of people start their dishwasher "cold," i.e. without running sink water until hot water heater level hot water is available in the kitchen. If they use dry dishwasher detergent, some of the undissolved dishwasher detergent, in every load, is captured in the "solids filter." You need to remove, dis-assemble, and clean the "solids filter," as well as any plugged orifices in the spray arm, spray tower, or pump drain. If your racks have any mineral buildup, you might want to run a few cycles of industrial vinegar, or CLR, but you can't expect a few cycles of such treatments to clean badly plugged "solids filters," or to remove heavy, hard water mineral deposits. If your dishwasher is leaving "speckly black bits" material on your glasses and dishes, you're going to have to physically dissassemble the various "solids filter" and "arm sprayers" to remove the solids, and give your dishwasher a new "lease on life."

You might also want to check your water heater outlet temperature, as this will be, at a maximum, what a dishwasher has to use as "hot" water. Some higher end dishwashers have a small, built-in "tankless coil," to "automatically" raise incoming water to 140°F to 160°F, as an aid to dissolving solid or crystalline dry dishwasher detergents, and sanitizing dishes washed. But the majority of low end home dishwashers take whatever "hot" water they are presented with, and go with that.

Many, if not most, American electric and gas hot water heaters installed in the last 10 years, have their internal thermostats set to a default temperature of 120°F. That's a responsible setting, to keep children and other family members from being scalded by hot water in bath and kitchen accidents. But, for many dishwasher applications, when the dishwasher is started without sink water being run to "heat up" the water line from the water heater, the dishwasher "tub" will fill with 2 to 3 gallons of water, at perhaps 70 to 80°F, which the dishwasher then uses as initial spray, and first wash.

Water at this temperature won't reliably dissolve solid or crystalline dishwasher detergents, or sanitize dishes.

So, even if you clean your "solids filter," you should check your hot water heater temperature, and adopt reasonable "pre wash" disciplines, with respect to running hot water in your kitchen sink, before turning on your dishwasher, to make sure you dishwasher is getting water that is hot enough to dissolve your dishwashing detergent, and sanitize your dishes, in a normal wash cycle.

Liquid dishwasher detergents avoid some of these problems, and generally contain free chlorine as a sanitizing agent, if you find that your "solids filter" is, in fact plugged with gunk. That's not to say you couldn't get the same level of sanitization/dish cleanliness with a powder or crystalline dishwasher detergent in your machine, only that the water/cycle temperatures need to be sufficient to dissolve dry dishwasher detergents, if that is what you use.
posted by paulsc at 11:04 PM on February 13, 2010 [27 favorites]

Wow, I've never heard of a debris trap. And I'm a reasonably clean person. Do people really clean them once a month?

I'd suggest cleaning this alleged debris trap out. I might do the same with my dishwasher, although now I'm kind of frightened. (Though I am, by and large, one of those aforementioned weird people who washes my dishes before washing them in the dishwasher.)

You do mention that the cleaning ability has deteriorated. When I use a less expensive brand of detergent, my dishes do not get as clean. I use some sort of super action power Cascade that is a vile blue color, and I hate using it -- but my dishes are always clean (couldn't always say this before when I was using store brand powder). I also find Jet Dry to be helpful for making the dishes a bit cleaner looking.
posted by k8lin at 11:31 PM on February 13, 2010

Hard to say where you poor wash ability is coming from. The white blotches are probably water marks caused by improper draining. The speckly black bits are often caused by either an impeller (part of the pump of the dishwasher) breaking down or some piece of black plastic (often a handle off a pot) getting chewed up by the impeller. If any part of the drain is partially obstructed the lack of expeditious drainage can cause dirty water to be recycled in subsequent cycles. Make sure the drain hose for the dishwasher isn't kinked under the sink. And check your spray arms for obstructed holes.

Many dishwashers have user cleanable traps which can be easily cleaned. If you're feeling adventurous then a little work with a screw driver in the bottom of the unit will often expose some or all of the pump housing.

paulsc writes "But the majority of low end home dishwashers take whatever 'hot' water they are presented with, and go with that."

Every single dishwasher I've ever worked on had a built in water heating element. They don't usually heat the water before it enters the unit instead they heat the water pretty quickly once the cycle starts. Could be some ultra low end model out there without an element but it would be a rarity rather than a norm.

Dish washing detergent doesn't need much help dissolving. It's mostly wetting, surfactants and anti sudsing agents and will dissolve just fine in cold water (try a spoonfull in a glass), though the water coming into your dishwasher will be at least room temperature. And the spray arms highly agitate the water/detergent mixture to mix it up.

Unless you are doing something else with the warm water out of your kitchen tap you'll be wasting quite a bit of water every month getting maximum hot water to your dishwasher by running your kitchen tap and it shouldn't be necessary as the first fill is mostly about knocking the big chunks of food waste off your dishes. The last fill is where any sanatizing takes place.
posted by Mitheral at 12:05 AM on February 14, 2010 [2 favorites]

"... It's mostly wetting, surfactants and anti sudsing agents and will dissolve just fine in cold water (try a spoonfull in a glass), though the water coming into your dishwasher will be at least room temperature. ...
posted by Mitheral at 3:05 AM on February 14 [+] [!]

Good suggestion.

I dropped a tablespoon of crystalline Cascade in a glass of cold tap water (about 40°F), 15 minutes ago, and, as far as I can tell, except for a slight change in odor over the normal, somewhat sulfurous, fairly calcium heavy Jacksonville, FL city water I drink and make iced tea with, everyday, it's just sitting there, in the bottom of the glass, undissolved, uninterested in dissolving.

Your thoughts?
posted by paulsc at 12:26 AM on February 14, 2010 [1 favorite]

Are you using a rinse aid? If you don't have any, try filling the rinse aid reservoir with white vinegar before buying any. That's all we use and never get spots on our dishes.
posted by DakotaPaul at 3:14 AM on February 14, 2010

They have dishwasher cleaners out there- after a while, mineral deposits build up on everything and water doesn't flow freely. Every time the stuff on my top shelf starts coming out more oily and dirty than it was when I put it in there, I run a cleaner through there and everything works fine again for a couple of months. You can find them in the same area you find the rinse aids and the soap.
posted by headspace at 6:37 AM on February 14, 2010

Don't bother with expensive products for cleaning the dishwasher. Just use Tang!
posted by SuperSquirrel at 7:03 AM on February 14, 2010

Had this exact same problem with my Kitchenaid dishwasher just recently (same type of dishwasher as the Kenmore, I think, but just with a different brand name slapped on.)

In my model the debris filter did indeed need cleaning (twice), and it also had a chopper blade attached at the top which was supposed to spin around and chop large food particles up enough to allow them to pass through the solids filter immediately below. This was not working properly because one of the gear teeth that held the filter/blade in place had broken off, and the blade wasn't spinning well enough to effectively "chop" up the particles. Thus the food was getting stuck on the filter and not allowing the water to flow through properly at all. The items on the top rack were barely getting wet because the spray was so ineffective. I ended up calling a repairman who had to order the part and replace it - total cost for everything - parts and labor - was about $120 (although I'm kicking myself as I've since found a set of do it yourself instructions, complete with pictures, right here.) That filter attached to the blade that you see in the picture probably needs a good cleaning. Just run it under the tap and pick the debris off with your hand. If you actually need to REPLACE the blade/filter assembly, you'll probably have to find the part number and special order it online. I don't think you can walk into your local Loews or Home Depot to pick one up.

Unfortunately, however, in my case that missing gear tooth (which was never found), ended up getting sucked up into the pump and the dishwasher started making terrible grinding noises and getting stuck midway through the cycle. Repairman came back and this time replaced the pump and the motor (so essentially it's almost like a new dishwasher again) - this time to the tune of $300. Sad me because I'm out the cash, but happy me because I am no longer eating from dishes lodged with filth.
posted by Rewind at 7:22 AM on February 14, 2010 [3 favorites]

For mineral deposits, running a ton of cheap white vinegar through a wash cycle cleans up most of it. You will see white film caked on especially plastic parts, and it's typical in hard-water areas. Your white blotches sound like hard water spots -- a vinegar rinse will clean those off your dishes. (Can't help with the black dots.)

I have very hard water; when I throw a dinner party, I always spend half an hour with vinegar cleaning my knives and wine glasses so they're not so spotty. :)
posted by Eyebrows McGee at 8:01 AM on February 14, 2010

I have heard, but cannot verify, that the liquid detergents have [something] in them that can cause trouble- something about the ingredient that keeps it liquid can also cause drain pipe issues. My mom got rid of a dishwasher because it didn't work any more, and uses the liquid, I cleaned some gelatinous goop out of the bottom (soapy goop, not biological goop) and have been using it for years not. YMMV.

Excellent answer paulsc.
posted by gjc at 8:20 AM on February 14, 2010

> Wow, I've never heard of a debris trap. And I'm a reasonably clean person. Do people really clean them once a month?

I just discovered the one in my apartment (clothes) washing mashine. I though it was some kind of bleach-holding thing. I'm pretty sure the last person who lived here didn't know it existed. Nasty, nasty, black goo.
posted by Decimask at 8:49 AM on February 14, 2010

I had a Kenmore dishwasher that exhibited the same problems as yours. It sounded normal, but didn't clean anything. It turned out the pump had gone bad (it was only 6 months out of warranty!). The repairman who came out demonstrated the problem to me by pushing some kind of switch thing on the front of the machine thereby tricking the dishwasher into thinking that the door was closed. In that way, you could see the inside of the machine while it was running ... and it was quite obvious that the water wasn't shooting out at nearly as much pressure required to get the job done. Hopefully that is not your problem also because it was very expensive to get fixed (I just bought a new one instead).
posted by Dave. at 9:16 AM on February 14, 2010

Wow, I've never heard of a debris trap. And I'm a reasonably clean person. Do people really clean them once a month?

My guess is no. I have helped with the washing up at a number of dinners and house parties in the homes of well-off, educated people who had the nasty, nasty, black goo problem in spade and had no idea that just removing the goo, instead of planning to call a repair man, was the answer for making the dishwasher "work" again.
posted by Lesser Shrew at 9:19 AM on February 14, 2010

I dropped a tablespoon of crystalline Cascade in a glass of cold tap water (about 40°F), 15 minutes ago, and, as far as I can tell, except for a slight change in odor over the normal, somewhat sulfurous, fairly calcium heavy Jacksonville, FL city water I drink and make iced tea with, everyday, it's just sitting there, in the bottom of the glass, undissolved, uninterested in dissolving.

Your thoughts?

Give it a brief stir, maybe? It's not like the detergent doesn't get knocked around a bit by the spraying water in the dishwasher. Very few things would dissolve immediately upon being dropped into cool water (e.g., a tablespoon of salt would mostly do the same thing until you stirred it).
posted by jedicus at 9:38 AM on February 14, 2010 [1 favorite]

Excellent thread! I also have a dishwasher that tends to get dishes dirty instead of clean. I now have the debris trap soaking in bleach water in my sink - the underside was solid black crusty EW. There is also some bizarre translucent chunky growths that look like coral. Minerals perhaps?

Hopefully the dishwasher will better after this. It can't be worse. :)
posted by WowLookStars at 10:35 AM on February 14, 2010

So, did your debris trap just come off, or did you need to do some heavy duty disassembly?
posted by leahwrenn at 11:07 AM on February 14, 2010

WowLookStars writes "There is also some bizarre translucent chunky growths that look like coral. Minerals perhaps? "

Maybe, if you've got really hard water. Often they are chunks of plastic or glass though that have been somewhat smoothed by erosion.
posted by Mitheral at 11:24 AM on February 14, 2010

We had the same problem. The dishes were so dirty that I thought maybe something was broken and water wasn't spraying in there correctly. I had a repairman come look at it and he said it functioned correctly.

Are you storing your dishwasher soap under the sink or somewhere similarly damp? According to the repairman that will seriously degrade the effectiveness of the soap. He suggested getting those "power pack" things that are individually wrapped. I thought that was complete BS, but using fresh dishwasher soap that stored in a dry place has helped our dishwasher a lot. We only buy the power packs now because they are so much better.

We also use Lemi-Shine in every load. That seems to help quite a bit. I tried Dishwasher Magic once and it didn't seem to help at all.
posted by 26.2 at 11:24 AM on February 14, 2010

bizarre translucent chunky growths

Detergent build-up?
posted by SuperSquirrel at 11:53 AM on February 14, 2010

Mine was attached with two small bolts. It was a little awkward reaching over the door and the water sprayer to undo them. The ratcheting socket driver was a big help. My kittens did their best to be a big help as well, but they were less useful.

The weird growths are definitely grown there, rather than a lodged piece of junk. They completely surround some of the little slats on the filter. They've dissolved in the bleach water without any help, so probably it was detergent build-up, yeah.
posted by WowLookStars at 11:56 AM on February 14, 2010

Unless I missed it above, I haven't seen anyone mention one key feature for a healthy dishwasher... Always, ALWAYS run your disposal with hot water before you run the dishwasher. Crap in the disposal can cause a backup into the dishwasher. gross.
posted by Edubya at 12:54 PM on February 14, 2010