Miele G646SC plus filling/drain problem

[stylers]

Hello All,

a neighbour of mine has a miele G646 SC plus dishwasher which recently started leaving water in the machine at the end of the drain cycles, and turning on the inlet / drain LED. I’ve had a look and from what i could see, it appeared to be pumping out fine, bt i checked the drain pipe, sink outlet and trap and the non return valve for blockages. everything appears ok and it is pumping out at full whack, but seems to time out. This is an electronic timer machine, and the drain time must be set in the software. I think its overfilling, and have checked the pressure switch and tube. When it times out, the water is just at the level of the removeable mesh filter.

What level should the water fill to on these machines, and is it possible that the pressure switch setpoint has shifted, or the pump timeout period has somehow changed ?. ( I’m not too familiar with miele’s )

I can get it going by restarting the cycle and pumping all the water out, at which point it fills and washes normally, but fails again on pumping out..

any help appreciated..thanks.

Owen.

[eastlmark]

Re: Miele G646SC plus filling/drain problem

The ‘set point’ will not change but the way the machine measures its water, by air pressure, is probably blocked hence the overfilling and not knowing its empty. You may also have burned out the heater if you keep trying to use it. Its a specialist appliance this one and would recommend calling an engineer.

[stylers]

Re: Miele G646SC plus filling/drain problem

Hi,

I have checked the pressure switch and tubing, and it seems ok. my guess is the pressure switch anyway..

thanks,

Owen.

[qas]

Re: Miele G646SC plus filling/drain problem

Most Miele dishwashers operate on a timed fill and timed drain cycle. The pressure switches are to check for overfill and sufficient water level to operate the heater.

The fill is controlled by a flow regulator inside the inlet valve and a set time so it is rare for these to overfill. Things which can cause overfilling are: a faulty inlet valve which doesn’t close fully or quickly enough, the valve being replaced by one with an incorrect flow rate or, on some models, a switch which extends the fill time (check the user manual for this)

If it is not draining properly, the likely causes are a blockage in the outlet hose or a worn impellor on the drain pump.

I would suspect the drainage as the most likely cause unless the machine has been played with or “fixed” by someone who doesn’t know what they are doing. I would never recommend anyone other than a professional to repair any Miele appliance as they are very advanced and it is easy to go wrong.

Steve

[qas]

Re: Miele G646SC plus filling/drain problem

stylers wrote:Hi,

I have checked the pressure switch and tubing, and it seems ok. my guess is the pressure switch anyway..

thanks,

Owen.

And the short answer: A pressure switch is most likely dearer than a professional (It is in Australia). It can be much cheaper to have it fixed than trial and error parts replacement

[stylers]

Re: Miele G646SC plus filling/drain problem

Ok, I’m not going to try and fix it (even though i do part time appliance repairs), I’m just curious as to the problem here.

I have checked the pump, non return valve and drain pipe, and all seem ok. i did notice though that it seems to work ok on the prewash, and it filled to what looked like a correct level, but when i put it on a wash, it filled to the same level, but on later inspection there was more water in it. Maybe the inlet valve is passing ?.

If the pressure switch is used as a safety switch in these, what happens if it actuates ?. Why is the timing of the drain pump so short ?

Anyway, talking about miele service, this machine was looked at before for what looked like a leak which was tripping the float switch. I diagnosed it, they hauled it off, couldnt find anything and left it back, where it worked up until now. When i had a look this time, the float switch was just left hanging above some wires to keep it off the bottom tray. effectively disabled !!. that would be nice if it actually flooded..

Owen.

[qas]

Re: Miele G646SC plus filling/drain problem

stylers wrote:Ok, I’m not going to try and fix it (even though i do part time appliance repairs), I’m just curious as to the problem here.

I have checked the pump, non return valve and drain pipe, and all seem ok. i did notice though that it seems to work ok on the prewash, and it filled to what looked like a correct level, but when i put it on a wash, it filled to the same level, but on later inspection there was more water in it. Maybe the inlet valve is passing ?.

If this is a machine with a “waterproof system” (the valve is at the tap end of the hose), this is very unlikely as these are a dual valve system and both valves would have to fail in the same way. If not a waterproof system then this is entirely possible. Does the machine fill at all between uses?

If the pressure switch is used as a safety switch in these, what happens if it actuates ?. Why is the timing of the drain pump so short ?

There are two pressure switches. One activates when there is sufficient water being pumped around inside the machine to operate the heater, the other operates when the machine senses overfill and operates the drain pump untill the switch resets.
The fill time and drain time are equal. When the pump is operating at full efficiency, the machine can drain twice the volume of water that the inlet valve will pass – if the inlet and drain are both operating, the machine will never accumulate water. (drain time should be about 1 minute)

Anyway, talking about miele service, this machine was looked at before for what looked like a leak which was tripping the float switch. I diagnosed it, they hauled it off, couldnt find anything and left it back, where it worked up until now. When i had a look this time, the float switch was just left hanging above some wires to keep it off the bottom tray. effectively disabled !!. that would be nice if it actually flooded..

Owen.

Unfortunately, there is always a range of service quality. My only comment regarding the above would be to not use that service company again.

Steve

[grooveguru]

Re: Miele G646SC plus filling/drain problem

Hi everyone

I have exacly the same model and the same problem.

I am a computer engeneer and Miele dishwasher is better built then some pc-!!!!

I opened it all up and discovered than the plastic part that is based at the bottom of the machine is cloged with some pinkish stuff that looks like grease to me. I tryed openning it to clean it inside but it looks like its sealed. Is it possible to open those up? I guess not…

I think this is the problem for me and not the timer.

Can someone please tell me if you ame accross this problem before?

Also, what is the part called? I could not find it on any spares sites.

Thank you!

[JulesWebb]

Re: Miele G646SC plus filling/drain problem

I have a Miele G692 SCI Plus which had a similar problem a while ago.
The inlet/drain light also comes on when there is water in the base pan. There is a float switch that also triggers this and over time if water has collected in the base pan the float switch can stick. Pull out the dishwasher and tilt it towards to back. If there is any water in the base pan it will come out. To be thorough, put the machine on it’s back and remove the base pan (4 screws by the feet), the float switch is a circular plastic casing with a polystyrene float in it. It comes apart for servicing, the float can jam if there is any rubbish in the water.

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