U-bend under sink has come detached

[Arbu]

The plastic U-bend under my sink has become detached. Unfortunately it must have been so for some time (in a better alignment than in the photo) and has been slowly leaking. It's in a disgusting state, I know. I tried screwing it back in without success. Should I clean it up and try again? Or does it need replacing?
Thanks

 

[Burnerman]

Probably no need to replace it, but for sure it needs a good clean!
You'll need to see if the water seals are all there though, once the thing is dismantled.
If you do need a new one, McAlpine are the make to go for
John

 

[Arbu]

I think you can see the pale blue item in the central connection in the photo which is presumably the water seal. Anyway, I cleaned it up, retightened it, and it has slipped off the central connection again after a few days. Also it leaks a little at the connection which is partly off the image at top right. So I suppose the next thing is to try a new one. I measured the downpipe at 40mm diameter so I think this is the thing to order - https://www.plumbers-mate-sales.co....ppliance--sink-trap-wm4---40004026-1652-p.asp?

 

[CountryFan]

Looks like it may have dropped, are you able to lift it up and try re-tightening?

 

[Arbu]

Looks like it may have dropped, are you able to lift it up and try re-tightening?

Yes, but in doing so I have to put quite a bit of force in pushing the two horizontal pipes upwards. After I've tightened it up the tension I have put into these two pipes pushes the central connection off again.

 

[Arbu]

The grey pipe to the left which feeds my boiler is unsupported and puts a lot of weight on the fitting. So I've put a paint pot under it to hold it up. But there also seems to be a problem that the downpipe from the left sink is not long enough and I just can't get a good seal on it. So still leaking unfortunately.

 

[endecotp]

the downpipe from the left sink is not long enough

I bet that originally the U-bend (let’s call it a W-bend) was higher up and more of the pipe from the left sink was inserted. Then the boiler (condensate?) pipe (grey) was added and to make it fit the W-bend has moved down. Now there’s not enough inserted for it to remain attached. That’s not easy to rectify now because the grey pipe is all glued together.

What’s going on with the right sink? It seems to have two traps, its own bottle trap and then the combined W-bend.

I would either try to add some more permanent support to hold everything in the right places, or replace all of it.

 

[Arbu]

Yes, I did wonder why the right sink is treated differently to the left one.

I made a mistake about the grey pipe - it's actually not connected to the boiler but to the outlet from the washing machine - hard to see down there.

Could I simply fit a longer pipe for the left sink? I note that the existing pipe has just been cut to size anyway.