Break-time over

Ah well, back to it.

Currently we're having a white/brown goods situation, so let's start with the dishwasher, which presented itself like this,

mmm, lovely.

After emptying the machine by hand and checking that the pump wasn't blocked and was running freely, running a rinse cycle replicated the problem so it wasn't a flyer. Taking the machine out of its' alcove showed that the waste path out of the washing chamber didn't seem too bad.

Water handling matrix of a Neff S51E50 dishwasher

The waste flow is the corrugated pipe coming in from the pump on the right-hand side and going up into the matrix, the flow then loops over and exits out via the white pipe to the back of the machine. Visually it looked OK. There does appear to be some residue in part of the matrix but A) I'm not sure this is causing the problem and B) there is no way in to clear it out as the matrix appears to be a sealed unit. Running a rinse cycle into a bucket worked fine.

The next port of call was the path from the waste pipe into the sink waste water plumbing. No need to see that part of the process, it was pretty foul (it'd gie yer the boke).

40mm waste water pipework

40mm trap seal (L - old/R - new)

After cleaning out many years of grot and replacing a dodgy 40mm trap seal that had been stretched and was leaking slightly it went back together no problem.

So all good, replaced the dishwasher waste pipe and ran another rinse cycle and hey presto! No change.

Disconnected and repeated the rinse cycle running it into a bucket: no problem. Is the pump not efficient enough? Ran another rinse cycle with the waste pipe elevated above the height it would usually connect at; no problem. Hmm..., reconnected it back to the waste piping and now it's back to working normally.

What was the problem? Basically I'm not sure. Current and final thoughts are

• Waste water was not draining, but pump was working. Therefore, probably, not due to a blockage in the waste path.
• So either the programmer or an associated detector wasn't working properly.
• No reason why it should just start working again if it was the programmer.
• A flaky sensor is a possibility but that is likely to reappear as a fault.
• Or the check valve on the waste outflow (if there is one) was allowing waste to siphon back into the machine.
• But on the first occasion the water was very gunky, indicating that it hadn't been through the rinse cycle at the end of the programme, so siphoning seems unlikely.
• Or the pump wasn't working properly.
• But if this was it, it must have been a blockage rather than a mechanical issue with the pump.
• Or repeated rinses may have removed an obstruction or crud and this might have brought it back to life.

Or in short, I have no idea but don't care as long as it keeps working.

Time spent : Day and a half, off and on.
Cost : £0.59 for replacement washer.