washing machine wont drain till most water removed by hand

[Neilj]

Hi
My washing machine (Miele W 754 S) wont drain when full but will drain and spin when most of the water has been removed!
Once the pump is going I can recycle all the water that I've just removed from the drum, into the powder inlet and it will drain the lot)
Worked fine for years up until a few days ago.
I've checked:
- The pump is working.
- The filter chamber is cleared.
- Five tubes connected to filter chamber:
-- Inflow to filter - Clear
-- Outflow, filter to base of drum - Clear
-- Outflow, small tube for emergency emptying - Clear
-- Outflow to drain hose - Clear
-- Inflow from side of drum (Is this an overflow?) - Clear

The filter did have coins and hair-grips in it which I removed. It was also stuck solid with limescale which I've de-limescaled. There was also lots of gunk that I've cleared.
It's stumped me.
Any ideas?
Cheers
Neil

 

[Mikefromlondon]

Not sure if I understood fully, you said when the machine is full, it does not drain nor spin,

Then you said if you empty the water, preasumably manually??? but how? do you have to advance the programme switch to drain cycle or do you have to open a hose from underneath to drain water ? and then you said when you have drained water manually, it will pump the remaining water out all the way and spin dry. So please elaborate a bit more.

However, the general principle of most domestic washing machines is that
there is a diaphram pressure switch, which is normally bolted to the top part of the machine, it has a small plastic pipe leading from the pump housing or sometimes even a lower part of the drum, the idea is when the water is filling in the drum, the level starts to rise and this creates the water level rising in this narrow tube leading to the pressure switch, when a certain amount of pressure is built up on the diaphram, this pushes microswitches or other contacts, and notifies the control board that the machine is now filled up and stops the solinoid taps to stop pouring any more water and starts the washing cycle.

The draining cycle commences when the load has gone through a complete wash cycle that you chose, it is the control board that determines this, and signals the pump to start pumping water out, so if your pump is not coming on then the problem has got to be the control board.

But oif your pump runs, and it is still not draining out , this is usually associated with blocked pipes, which in your machine is no longer the case as you have just cleaned it up and checked none of the pipes are blocked.

But becarefull, the smaller tube connecting to diaphram pressure switch can cause unpredicatble results if they are blocked with gunge, soap residues and so on, so they need to be clear real well, often they may seem open but things can get blocked again and again, so make sure this pressure switch tube is absolutely clear to where it is connected, and that the inside of this pump housing is also very very clean, as any loose debri can enter the small tube again soon after you cleaned it up and blocks this pipe.

i have seen washing machines that would not stop filling as this p/s pipe is blocked, and then continue pouring water into the machine until it overflows from the top, and flood the kitchen, and on the other hand it may not stop draining and continue to pump even when the water has emptied, because the blockage is still keeping the microswitch active and so it continues running the pump for hours!

But other than this, the important thing is that it is the control board that has to first attempt or signal the pump to empty, whether or not your pipes are blocked.

Some machines have multiple level pressure switch where depending on the wash cycle and programme, it can part fill the drum, to save on water, or fill to normal level for a full wash. One word of advice, never alter any settings on these pressure switches, as nearly always the cause is blocked pipes and not the settings.

 

[Neilj]

Hi Mike
Thanks for your response. Here we go then ...
When machine is full, it does not drain nor spin:-
Machine seems to work right up to the rinse cycle. At the point where it should drain, it simply clicks through. When it gets to the final spin, it simply clicks through and leaves a pool of water.

Emptying manually:-
I open the door and use a bowl to scoop the water out into a bucket. I have also drained it with the drain pipe but that takes longer. Once most of the water is removed (a bucket full), I close the door and try the ‘spin’ and behold(!), it spins and drains.
Re pressure switch. Interesting your points re the the pressure switch. Here’s a thing. If (switch off and) move the programme to the point where the pump should kick in and I disconnect the pipe to the pressure switch, (then switch on), bingo(!) the pump kicks in! I also notice a slight hiss when I disconnected the pipe to the pressure switch suggesting that the slight pressure caused by the well of water in the drum was causing the pressure switch to switch off the pump???
Re control board. I fear you might be right. Unless above changes your thinking?? Why would the pressure switch under pressure stop the pump and release of pressure allow the pump to run? Beats me.

Re pump runs and it is still not draining out. Yes but when the pump runs it drains. The pump does not start and stop or fight a blockage. I’ve only discovered this in my many attempts to fix it, in the process of checking and degunking the various pipes.
Re pipes connecting to diaphram pressure switch. I did previously blow down the tube (in direction away from switch to drum) and it seemed clear. This morning, I had a go at cleaning the air dome / drum end and de-gunged that end of the pipe and later I will take it apart again and send a wire from the other direction and see if any residues there.
Interesting what you say about pump “continue to pump even when the water has emptied, because the blockage is still keeping the microswitch active and so it continues running the pump for hours!” Once I’ve got the pump going by the ruse above (emptying manually), I notice that the pump carries on ‘emptying’ long after all the water’s gone. So perhaps there is still some gunge in the air dome / pressure tube. I’ll have a look.

As you advise, I wont alter any settings on these pressure switches. I have one last degunging job to attempt and then it’s ‘call the engineer’ (Miele have sent my details to an engineer and I’ll make contact after the bank hols).
Cheers Mike.

 

[Mikefromlondon]

Glad to hear that my post was of some help, now that i have some more ideas what may be causing the problem, but i will need your help first.

I got a feeling that somehow the pressure in this pipe escapes slowly, so there has to be some sort of slow leak, somewhere, such that when the machine has finished the wash cycle and is ready for the final drain and spin, then by this time the pressure has already escaped and the pressure switch contacts returned to normal, and the control board thinks the water has already been drained!

in other words, when your machine starts filling up, the pressure rises fairly rapidly, despite the slow leak, causing the pressure switch to operate and close off the water filling solinoid valves to shut, and commence the wash cycle.

after the wsh cycle, when the machine is ready to spin dry, the pressure from the pressure switch has already leaked away, and so the machine never commences the spin dry cycle.


So check for any leaks or slow leaks, how you do this?

very simple, but you need a clear tube to see where the water level has risen to when you have just started a new wash cycle, allow the machine to start filling up, when it has filled up to the normal level, the pressure switch will trip the contacts, and water solinoid valves will shut of filling up, and the machine will start to conduct the wash cycle slowly spinning one way then pause and then spin in the opposite direction.

Just then, switch off your machine from the Mains switch, and wait for an hour and then switch it back ON, if the machine continues to where it left, then the pressure switch may be fine and there is no leak and the level of the water in the tube should have remained at the same level, but if the level has dropped off, then and the pressure switch has tripped back to normal, then the machine may either refuse to continue from where it left or it may start filling up again despite the fact thhere may already be sufficient water in the drum.

So please conduct this test and come back, it may seem that all you probably need is a ne switch or a new pipe that may be leaking slowly.

But if the machine starts to fill water again for longer than say 10 seconds, then switch off as you may risk overfilling it,

to drain, remove the tube from the pressure switch and see if you can hear any clicks or a hiss, as the trapped air escapes if there still is some in there,

but now you must somehow trip the pressure switch On, with some pressure, you can either use a small pipe from your own garage, or junk! or if you can't find a suitable pipe, then blow back into the tube such that the tube is now completely empty of any water, so you would hear some bubbles coming out of your drum, then quickly place your thumb over the tube end, so as to stop water getting back into the tube from the drum, and quickly shift it to the pressure switch nossle, and push it on, hopefully as you do this, the water will enter the emptied pipe and start rising and trip the pressure switch on, after doing this switch your machine to spin and dry setting and then switch On from the mains., hopefully this will drain your machine, and you would know that you now need is a new pressure switch or a new tube that may be leaking slowly.

 

[Neilj]

Thanks Mike
I like your idea of pressure escaping from the pipe slowly.
And I agree with your logic as my thinking (if I had thought of that) would run the same way.
However ...
Having just finished cleaning out the gunk from the air dome which is connected via tube to the pressure switch I reconnected and tested and got same problem.
So, whilst ‘full’ of water and in the point of cycle where it should be draining, it sits there as before ... so I disconnect the pressure tube. There’s a hiss, indicating some pressure and ... immediately, the pump kicks in.
This is what happened last time I did this, so at least the machine is consistent.
The only snag is, I would, like you, expect it to empty on high pressure not low pressure??? But it seems to be doing it the other way around. Plot thickens. Makes no sense to me. It’s counter intuitive (and suggests that if I had a slow leak then eventually the pressure would drop enough and the machine would empty!)
However, I still think there’s mileage in your idea and next time I have the front off, I shall have a play with the pressure tube and pressure switch.
Cheers Mike

 

[Mikefromlondon]

So there appears to be no leak, and as you said it appears to go when it shouldn't i.e. when you remove the tube from the pressure switch, it then goes, which is totally opposite of what it should do!

My next step would be to check the contacts on that pressure switch, for which, you may need a cheap multimeter that you can pick one up from Maplin or halfords, or some other electrical stores for under a tenner, yes you do not really need a pricey one for most DIY home testing, but make sure it has a continuity tester buzzer, this really helps as you hear a beep when checking continuity between contacts, but at the same time observe the contact resistance which should be almost down to 0.05 ohms or less, as close to zero as possible, anything more than about 1 ohms means a likely problem with contact resistance.

If you do not know how to , let me know, a picture of the switch with any contact markings could help, and sometimes there could be more than 3 terminals as some switches use multiple contacts, so it can be possible one of the sets of contacts is playing up.

Let me know how many wires are connected to this switch, and note their colours where they go if you need to remove any wires, they must go back exactly where they came out from, so always jot them down.

The terminals may not be marked, but it is relatively easy to determine which is a common (C) and which is Normally Closeed (NC) and which is (NO) normally open contact by using a continuity checker on a multimeter, and then you check again this time by pushing a mouthfull of air into the switch until you hear a click, this time the continuity will reveal that the NC contact has become NO and NO has become NC when measuered with the common terminal, and check the resistance, any problems with the resistance can cause the board to malfunction.

Finally, as we know your machine appears to work opposite to what it should do, it should drain when the pressure switch is still tripped, and it doesn't and it responds when the pressure switch drops out when you remove the tube, this strange fault can be down to corroison on the board, so check the board has no undue corrosion or any sign of water ingress, including no jokes, but sometimes insects and mice piddle can cause havock!Also just sorted out another problem with a similar diaphram switch on a boiler fan faiure switch, that had gone wrong, the contacts were showing high resistance so replacing just the switch cured the fault on a CH boiler!

so let me know if you can test your switch contacts, and if not then I can guide you how to do it.


But before you do anything please let me ask you one important question: when it is doing the normal wash cycle, you know the drum spins in one direction then pauses and then in the opposite direction, and after a good few minutes of washing, it gets to a rinse cycle, where the soapy dirty water is expelled and fresh water is induced to start rinsing process, .......so now tell me if this draining process functions ok, that the dirty water gets drained? after a few rinse cycles, may be 3 or even 4, to get rid of the soap, after the clothes are rinsed of any soap, and on a final rinse cycle the conditionr is dispensed with more fresh water, which is a final risns cycle, then after tye conditioner cycle, the Final drain and spin dry cycle begins, this is where I beleive your machine gets stuck, so can you confirm if rinse cycle before the final drain and spin cycle functions Ok?

 

[Neilj]

Hi Mike
Thanks for the tips.
Why the pressure switch appears to be doing the opposite of what it should do, foxes me completely!

I’ve ordered a multimeter from ebay and apparently it’s been dispatched already.
I’ll readup on how they work when it arrives ... ‘contact resistance <= 0.05 ohms’ and >= 1 then possible problem ...

Re possible board corrosion, didn’t notice any but wasn’t looking for that. Will look for it next time I have it apart.
I agree re bugs and boards, they also do the same when they get into computers.
I’ll post again after I’ve had a go with the multimeter.
Cheers Mike
Neil

 

[Mikefromlondon]

Brilliant, a multimeter is a very handy tool, one is lost without it, if you need to know how to use it effectively then let me know or ask, no point seeing some figures on the display unless you are very sure what you are looking. Youtube may have some helpful videos on how to use these.

Yes at the moment i am stumbled as well regards to why your machine gets stuck after a wash cycle, although it may not be, but it is best checked if the contacts are operating as they should, without any resistance, you never know as often a few ohms over a good clean contact can prevent a function, as per my recent example of a boiler fan failure switch, a Gloworm Micron 40FF has a micro switch in its fan failure capsule, that switch has very soft button, and it wasn't functioning properly and its contact resistance would vary from time to taime and so it often worked and other times it didn't, after changing the microswitch it cured this erratic behaviour.

One of its NO contacts when closed was only showing like 200ohms as opposed to almost zero ohms.

Toady I went to have a look at a Service 1200 washing machine, as the owner complained that it stopped half way in its wash cycle, so he had to remove the clotrhes and wash them by hand and was showing me a blistrer on his thumb! (lol)

But i checked the machine, suspected motor brushes, but they were all fine, checked field coils, and hall effect sensor, all were fine.

Checked board, no corrosion, no sign of any [parts having got overheated, so put it all back, checked heating element, and its all fine, so couldn't see anything unsual, multimeter read everything fine, checked door lock override and micro switch, all was fine, so put everything back telling the owner that I cannot see anything that should make that machine stop half way, and asked him if he was sure 100% that it had stopped and not just assumed it had stopped as it could be waiting for the water to heat up, so he said he was sure it had stopped, I did a full run and it worked all the way through! Couldn't fine anything wrong! so left him to run it a few times in case it is a random fault.

 

[TicklyT]

Had similar symptoms with our old washing machine not pumping out water when full.
After years of (ab)use, the suspension had settled a bit, kinking the hose from the drum to the pump. The weight of a full (over)load plus water kinked the hose further, just far enough to pinch off the water flow to the pump. Unload some of the weight, and the kink opened up enough for the pump to work, and pump out the remaining water.

 

[Neilj]

Thanks T, that was a great idea. Hadn't thought of it myself. Got my hopes up for a minute. Sadly, just had a look inside and no files bent only the concertina pipe under the drum and that is as it should be. Thanks for the thought. Neil

 

[Mikefromlondon]

any luck so far? did you check if the contacts were Ok, changed over from NC to open and NO to closed with respect to Common terminal, and I asked you if yours pressure switchy has 3 wires or more?

Sounds like a control board problem if the switch is OK, the board would obviously rely on inputs from sensors and switches, hence why I first asked you to check contact resistance of your pressure switch contacts.

The problem on the board can be the firmware, or simply things like dry joints, or corrosion, so may be worth checking for a close inspection after removing the board out from the machine and check its other side as well.

sometimes just taking the bioard out and re fitting it solves some issues with contacts with the conectors plugged on the edge of the board.

 

[Neilj]

Hi Mike

Multimeter has not arrived yet. (Hand pump wastepipe unblocker has arrived but I no longer need that!).

Re contacs on pressure switch (TNR 1418664). Yes I did take a look (and photo). Seven wires:
11. Two Black wires, one of which goes to #21.
12. White.
13. Green-White.
21. Black connection from #11
22. Brown
23. Brown-White.
24. Two Black-Yellow wires

All the contacts looked Ok, well seated and not corroded.

Will test switch when multimeter arrives.
Dont know what NC to open and NO to closed is but will worry about that when the mm is here.

Interesting what you say about taking out and refitting the board. I'm tempted.

Cheers Mike

Neil

 

[Mikefromlondon]

with so many wires, it appears to be a complex presure switch, and a multistage one too, that is it is used in some more complicated and expensive washing machines where different wash choices are available such as half wash, full wash, and to conserve water etc, or often where wash cycle takes lower amount of water than during a rinse cycle, there is a whole lot of variations in what you can get these machines to do through the firmware, but the firmware needs feed back via the seners and multistage pressure switches, so there you are, a likely candidate for a malfunction may be to do with your pressure switch, this can of course be checked using a multimeter, how to test it we can device a contraption, I use a clear plastic tube of about 20mm diameter, and one end of this tube is sealed and at the bottom you drill a small hole to take the tube to the pressure switch, and start filling water from the other end, and as the water in the tube rise, the pressure switch stage 1 contacts operate and then as you continue filling more water stage 2 contacts close and there may be stage 3 contacts, but nothing there you can't check to determine of you need a new PS, but most people would just go and try a new PS and if it wasn't the culprit then you have wasted a few quid, on the other hand buying your own Multimeter and fi9nd that the PS worked Ok, you really haven't wasted your money as you now have a MM that you can use often on other th9ings, and it is a hyandy gadget for all DIYers.

To test a switch like the one you have, you start from one end, and put one of your mm continuity probe on say the left most terminal and with the other see if you can establish any relationship with any other terminal, this you do with the conector from the machine disconnected, and then as yt

 

[Neilj]

Thanks Mike

Just had the back off to check that all connections were well seated and they seem fine to me.

Yes, it's beginning to look like the pressure switch. It's not allowing draining when under pressure.

From previously attaching another tube to the pressure switch and blowing gently, I think there are three clicks.

Next step, multimeter.

Cheers Mike

Neil

 

[Mikefromlondon]

Brilliant, just wait for your multimeter, and you will have more fun and feel proud that you have fixed your own washing machine, and begin to understand the basics, with this knowledge you will never be shy to look at problems again, that is how you learn most things in life by doing them yourself. give me a shout and I will guide you how to use a multimeter and how you could test your switch and its multistages, step by step.

but try and get a plastic clear tube from somewhere,and block its bottom end by filling it with hot glue , or some other way, and drill a small hole at the side of the tube as near the bottom as possible, and attach to it a small plastic tube, or you could borrow the one from your machine, but note how it is routed as that effects the pressure switch settings,so when you replace it back, it must run through the same route.

I am not sure if I have covered this before, but I should have before asking you to fiddle with your pressure switch, .....Your pressure switch may be nothing wrong with it, but quite possible the control board is either issuing a command for something to happen like for example heat the water, and since the element may have gone open circuit, and so the water is not heating and therefore the temperature sensor may be still showing water as being cold, and the board stops the machine, cycle does not complete and hence the draining or spinning may not start, so have your element also checked with the multimeter, it show a relatively low resistance like less than 10 ohms, as the resistance depends on its Kw rating,

One way to test this problem without a multimeter is to get a couple of buckets of hot water, and slowly pour it into the machine from the drawer, open the drawer and pour hot water into the machine, and then fill it up to the bottom of the door window, around couple of inches of water you should be able to see, then choose a programme that is of lowest temperature wash like 30 degrees, and choose a quick wash or a programme that is for delicates, as this would take a lot less time to wash and may not require all 3 stages of the pressuer switch operation, so run this programme and see if this time it completes the cycle, if it does then, it may be that your heating element may have gone open circuit, this you can measure with your multimeter on a Ohms range of 200, and should read under 10 ohms, but disconnect the wires from the elment when ,measuring, the element is at the rear bottom and you will see two studs poking out with an erath connection on an oval shaped element seen from the rear.