Miele G646SC dishwasher water leak - applies to most models

[jenningsp]

My Miele G646SC has developed a water leak between the main circulation pump and the main filter housing. It just drips into the water collection tray and trips the flood protection switch. This stops the machine from running and then continually run the drain pump until the water evaporates away or the water is tipped out. I normally try to repair these types of fault myself. Any advice on the practicality of this and the basic sequence to dismantle. It looks as though the whole pump and motor assembly needs to be removed. Any views on the cost if using an independent engineer. Miele seem to want £250 albeit with a years warranty etc for any other fault. Many thank for any help.

 

[jenningsp]

Having now done the research the union seal between the main circulation pump and the collection pot can be replaced as follows (see image of diagram in my album Miele G646SC Water Leak):-
1. Remove all water from the Sump.
2. Remove the Fixing Bolt (Item 5), from the Casing Rear Panel (Item
4).
3. Lay the dishwasher on its back.
4. Remove the Drip Tray (5.30).
5. Disconnect the Connection Plug (Item 7).
6. Remove the Heating Level Switch (5.39) - only if replacing the pump.
7. Release the Hose Clips (Items 3 and 8 ).
8. Press the Rear Casing out slightly, to remove the Spacer (Item 9).
9. Loosen the Circulation Pump (Item 6), and remove it.
10. When refitting, ensure the Seal (Item 2), is seated correctly.

Service Tip
The use of a small amount of Rinse Aid may assist in getting the
seal positioned correctly. Do not use liquid detergent, this will
cause an oversudsing condition.

The Miele part number of the seal is 5229531 and is widely available on Ebay for less than £10.

As a matter of interest I noticed my pump was slightly out of line with the housing. I stopped mine leaking after pulling it back into line. If it leaks again I will replace the seal.

Hope this helps - does not appear to much info on the net - suppose generally they are very reliable machines.

 

[jenningsp]

Just to complete this post it did leak again so I can now tell the full story. As well as the union seal there are also two seals in the pump housing.
1) An O ring Part No 6090860. Dimensions are 105x3.55mm. This can be purchased as an individual item from Miele or Ebay - cost about £2.00.
2) The housing seal which is only supplied with a new partition housing kit - Part number 5011733 - cost on Ebay from Germany about £67.00 for a genuine part. This kit also contains a new impeller and the O ring.

To check out what is happening:-
1) Remove the fours bolts securing the housing to the motor
2) Remove the top part of the pump housing
3) Remove the impeller - Left Hand Thread - hold the shaft by putting a screw driver into the cooling fins at the base of the motor
4) The housing seal is now exposed

Inspect the O ring and the housing seal. If the housing seal is OK and there is evidence of the O ring perishing you may get away with a cheap repair. If not will need the partition kit at a cost of £67.00. Not cheap but a proper repair which is likely to last the remaining life of the machine.

The housing seal was damaged on mine and was the real source of the leak. I managed to salvage a decent partition housing from a scrapped machine - a cheap option if you can find one.

While all this was going on I kept the machine running without the under tray of the machine being fitted. Screwed a couple of wooden blocks where the back of the tray is normally secured to act as rear legs and put a shallow tray underneath to catch the drips whilst it was still leaking.

Everything now working fine.

Have added a photo to the album to show the offending bits.

 

[Simon Hedges]

Thank you so much for this very useful repair guide. We would not have attempted the repair without this guidance.

Only one comment is that the step:
"Press the Rear Casing out slightly, to remove the Spacer (Item 9)."
Implies that the spacer can be slid out whilst leaving the motor in place. In actual fact it is fitted into the back of the motor so we got it out by flexing the casing and pulling the bottom of the motor and the spacer out together. Refitting is the reverse.

Thanks once again.

 

[Arkers]

Hi,

I stumbled upon this thread after trying to figure out why our Miele G 638 Plus has started to fail. I'm not sure if the issues are related, but it sounds possible.

The problem with our G 638 Plus is as follows:

1. After pressing Start, the pump runs for a few seconds and then stops, with the Inlet/Drain light illuminated on the front panel. This is reproducible most times I attempt to run the dishwasher.
2. The only program that completes the most reliably is the 75ºC cycle.
3. I've checked the impeller for free movement (no issues there) and attempted to reset the machine.
4. I've also checked and cleaned the inlet hose where it connects to the water supply and I've checked the drain hose for any obstructions. Both seem clear of any issues.

I just ran the dishwasher empty, after sitting dormant for a couple of weeks, and it completed a 75ºC cycle with no issues. Weird.

I wonder if I have a leak (similar to the leak described above) that has dried out during this warm spell of weather. It's a pretty old machine. I would estimate it's 17 years old as it came with the house when we moved here 10 years ago.

I would eventually like to replace this dishwasher, but both Miele and Siemens have sporadic stock in the UK at the moment (they are blaming coronavirus and social distancing in the factory) and figured I might be able to attempt a DIY repair until they sort out their stock issues.

Do you know if this repair might also apply to a G 638 Plus, please?

Thanks,

Steve

 

[jenningsp]

I am really sorry I did not reply to you question. Unfortunately I have only just updated my email on this site and the old one was just going into the ether.

Most, if not all, these machine have a flood protection system which is triggered when water drips into the under tray.

This dries out on its own in time and suddenly you can get a clean run as you have seen. However, used regularly the leaking water will build up again and the flood protection system will kick in.

There are various possibilities for a leak, including the one I described. You need to have a good nose around the machine to see where the leak is coming from. Some of the possible leaks are very simple and cheap to fix.

Hope this helps.