How can I unblock washing machine drain pipe?

ThisIsWeird

Okell said:

I won't be back at home until after Christmas so can't provide photos (of what?) at the moment.
The waste pipe is just a vertical plastic pipe about 1.75" in diameter, about 30" high with a U (or P?) trap or bend at the bottom.  It exits the kitchen wall and outside it joins the waste pipe from the kitchen sink.
Nothing like grease or fat goes down the kitchen sink - it all goes in the bin - and I can't imagine what from the sink could possibly cause a blockage.  The sink drains perfectly well - I can tell that from watching it drain and listening to it drain from outside.  And wouldn't the sink back up anyway?
Also the washing machine is currently draining into the sink - no problems whatsoever.
As regards what could come out of the washing machine to cause the blockage, I assume it's lint and fluff etc as suggested by @EssexExile.  Obviously it's been small enough to get through the drain pump* and filter as that is all working ok.  In the 25 or so years we've lived here, this has happened no more than half a dozen times and it's always been sorted out with the snake.  I'm puzzled as to why this seems to be immovable.
I don't want to, but I suppose I'll have to disassemble the waste pipe

*My wife has a tendancy not always to check her pockets etc are empty when washing her clothes so we've had to clean out the drain pump and filter several times.  The machine itself is draining perfectly well so I assume the drain pump and filter are OK.  (She's a rower and after working on her boat she once left a 9" screwdriver with her clothes and it ended up in the washing m/c.  Fortunately it made such a racket we were able to stop it before any damage was caused.  This was several years ago.  Hair pins too...)

Photos of the items you may need to dismantle, so we can guide you. Hopefully they will be 'compression' screwed connectors, so relatively easy.

If previous blockages have been cleared using a snake, then that suggests it ain't anything more worrying than stuff coming out your W/M. I have to say, that is unusual, tho' - the relatively small amounts of flint are usually swept right away with the large quants of water. And larger, solid, objects such as coins and hairclips should normally be caught in the WM's filter. 

Possibly there's summat caught in your U-bend, a sideways hairclip, so if this isn't removed, you'll remain prone to repeated blockages - which, I'll repeat, is otherwise unusual. I have never had a blockage in my white W/M waste pipe. Plenty in the filter... 

Anyhoo, 'hope you have a nice Christmas, and come back when you are ready.

CliveOfIndia

Okell said:

The waste pipe is just a vertical plastic pipe about 1.75" in diameter, about 30" high with a U (or P?) trap or bend at the bottom. 

The trap at the bottom - is that solvent welded to the downpipe, or is it a screw-fit assembly?  If the latter then it should be a simple job to unscrew it and give it a clean.  There's no guarantee that's where the issue lies, of course, but as it's a very quick and simple job, there's nothing lost by giving it a go.

Okell said:

It exits the kitchen wall and outside it joins the waste pipe from the kitchen sink.

Whilst you've the u-bend off, you may as well take the opportunity to use your snake to clear out the pipe that runs to the outside.  You'll probably be able to give it a more thorough clean than you would if you attacked it from above with the u-bend still in place.

Wyndham

I know you say that the machine itself is draining, but you have checked the filters haven't you? I'm amazed at what mine pick up sometimes, and tend to clear them around once a month.

Apologies if you've already tried this, but I thought it might be useful to mention it, just in case others see this thread and are looking for things to try.

JohnB47

If this keeps happening, I would not keep trying the same old method, time and time again.

I'd just get in there and completely remove and replace the existing waste pipework, and trap, all the way from where the washing machine hose hooks into the top, to the point outside where it joins the pipework coming from the sink (which seems to be clear).

So, don't try unblocking it, replace it. And take it to bits to see what's been causing this all along (I agree with others  that it's probably some sort of permanent small restriction that encourages a build up over time).

Reminds me of a problem I had after workmen put in a new driveway. Some 3 or 4 months later our sewer backed up. Long storey short - it was a small blob of mortar stuck to the side of the sewer S bend in an inspection chamber they'd been working at the top of. I 'cleared' that blockage only for a repeat some 6 months later. It was at that point that I discovered the blob of mortar. I knocked it off with a hammer and chisel and it hasn't been a problem in around 12 years since. Just that one little piece of restriction was enough to allow a build up over time.

ThisIsWeird

Replacement is almost certainly unnecessary, and would also move what should be an easy DIY job for 95% of folk, into a different league where tools and saws and all that malarkey are required.
We are waiting for a pic, and if it's easily for the OP to remove, it'll be very straightforward to check and clear anything that could be causing this.

poppellerant

What detergent are you using in the machine? Liquid can cause build ups in the pipes and the machine itself.  I've heard of people using liquid pods on quick washes, which often don't allow enough time for the pod to dissolve completely.

I know you've said the washing machine is draining fine and I believe that.  But once you get the pipes unblocked, run 250g of soda crystals on the machine's hottest wash - normally cottons 95c.  Don't be tempted to rush the program by using time saver options, but use any options (such as Aqua Plus) that increase the water levels if available.  Better still, use the drum clean cycle with the soda crystals if your machine has such a cycle.