Dishwasher - dishes in top rack dirty

[Lobster]

Have been trying to work out why our dishwasher is no longer cleaning properly (a 5-yr-old Bosch built-in; can't find a model number). Basically, stuff on the top rack, and sometimes on the bottom one, invariably comes out with gritty residue stuck all over it. Things I've tried out/checked:

- Ensured spray holes in rotor arms aren't blocked;

- Cleaned filter in bottom of machine;

- Opened door mid-cycle to check rotor arms move (but can't tell how vigourously though)

- Changed detergent (we're in a soft water area so no need for softener)

During the wash, water reaches the upper rotor via a flat grey conduit attached to the inside of the machine, and which mates up at the back of the upper rack with an aperture leading to the upper rotor; I'm guessing that for whatever reason not enough water is getting through? How can I tell?

One thing I've noticed is that after a cycle, if you lift the filter the water in the machine's sump is really mucky; is that normal or should it be basically clean 'rinse' water down there?

Any advice much appreciated!

David

[EricP]

Only thing you can do is start it and open the door when it's working on a wash.

That way you can see if the top impeller is working and the amount of water in the top.

It's not as dramatic as it sounds, but put a towel on the floor at the sides and wear some sort of eye guard.

[Lobster]

Yep, tried that (see above)! It moves, and there's water up there, but is it 'adequate'? Presumably not...

David

[EricP]

Ours does peculiar things. Washes perfectly a dozen times and then 13 and 14 look as dirty as when you put it in.

[Lee]

Just a guess, but I wonder if it's draining properly? Just thinking that maybe it's draining just quickly enough not to stop the machine from working, but not quickly enough to remove all the dirt

- so it's still there for the next wash...

Lee

[Chris]

Not being funny but does this model have a half load button ?, a mate of mines girlfriend accidentally set his dishwasher to half load and they thought the machine had stopped working properly until they spotted it

[Dave]

What I would do, is to put two identical bowls open side up. One on the bottom shelf and the other on the top one. run the machine on a rinse for a predetermined time. The bowl on the bottom should have about twice the amount of water in it that the top one has.

Logic being, the lower bowl will collect water from top and bottom spray nozzles, where as the top one will only get water from the top spray.

I would expect that to be clean cold water. The last thing a dish washer does, is to take on board cold water. This helps the drying cycle by condensing the steam/water onto the base of the dish washer.

Dave

[Lobster]

As I've just resorted to calling out an engineer to sort out the machine (cough, spit) I thought I'd report back on the outcome for the benefit of anyone else similarly afflicted... the guy pulled off the front of the machine and disconnected a flexible hose which led into the sump, through which the water circulates throughout the wash. It was totally clogged up with gunge; once that was cleaned out the machine is working like new.

Don't you just *hate* it when that happens? Oh well, at least I'll know how to d-i-y it next time it occurs.

David

[Brian Sharrock]

Out of interest:: how did the guy 'pull off the front of the machine'? I see a pull-down door-front . I'm really interested and will put the info into my 'Just-in-Case' memory.

[Andrew Gabriel]

There is some type of grease which dishwasher detergent fails to dissolve, and it does build up in the pipework eventually blocking it. You can avoid this by either running the machine with a dishwasher cleaner occasionally, or by adding one drip of washing up liquid to each wash, which does dissolve this mistery grease.

[Matt]

There is one type of dishwasher contamination that makes the dishwasher (and the whole house) smell just like a backstreet garage - the first and only time I put a few engine parts (actually a cylinder head) in there for a quick rinse before commencing a rebuild will be my last. Fortunately SWMBO was away on business for the whole week. It took me about a dozen dummy washes to get rid of the smell - a mixture of hot gunk and old engine oil was wafting through the house every time and I was rapidly running out of ideas. The final desperate solution with a few hours to spare was to use some shower gel - got rid of the stink and the dishwasher came up looking like new.

[Lobster]

Sorry, I was just being a bit flippant - he unscrewed the fixed metal plinth below the door to access the hose.

David

[graham]

A friend of mine used to be a nightclub lighting engineer.

They would dismantle some of the lights, remove the electrics so they were just left with the metal or plastic housing around the light itself.

He said a dishwasher was great for getting all the tar and gunk off the lights.

Graham

[Pete C]

Hi,

If the DW does a _cold_ prewash, IME it's possible to use a _lot_ more than one drop as a prewash detergent without it foaming excessively, and it helps degrease the plates etc for the main wash. I just keep adding 10 drops at a time until it starts to foam.

I'd expect the powder DW detergents work by dispersing grease with the aid of hot water, however it can then solidify in parts of the machine if they are cooler than the water.

cheers, Pete