Leaking concealed cistern with no thread on the pipe going to the flush pipe

[Tessa1]

Hi, i noticed that the downstailrs loo was leaking and have managed to take apart the cover and have found it is leaking where the flush pipe joins the cistern. The cistern is in a metal back to the wall frame, and the flush pipe was attached with the pipe just sliding on to the pipe coming out of the cistern. There were a couple of thin rubber/plastic washers but that is all that was keeping the water in the pipe and it looks like it has been leaking for some time.
Looking online to see how this should be attached it seems that normally there is a thread on the pipe coming out of the cistern, and the flush pipe is attached with a compression nut and washer. But there is no thread so cannot get a compression nut and washer to sort this out.
Does anyone know how to make a watertight seal when the pipe coming out of the cistern has no thread. For now the toilet is out of use until this conundrum can be fixed.
It was clearly made that way so there must be some sort of solution.

 

[denso13]

Any photos?

 

[Tessa1]

 

[Tessa1]

The outlet from the cistern just has the two little washers as you can see above, and the flush pipe just slid over the top and was leaking. Sorry the photo comes out so large, but you can see if you scroll down what i mean.

 

[Tessa1]

I seem to be talking to myself but if anyone sees this and has an idea, would this work
https://www.screwfix.com/p/mcalpine...VwaaDBx19_BIQEAQYASABEgI6AvD_BwE&gclsrc=aw.ds

 

[oldbuffer]

1. I've not seen one like that before. Is it possible that the white plastic part with the two O rings is itself screwed onto the more normal threaded end of the syphon or flush valve within the WC cistern? Is it possible to remove the insulation jacket and have a closer look?
2. The Mcalpine part you refer to is unlikely to solve the problem. The outside diameter of the part with O rings would have to be 50mm, +- a millimetre or two. You would also need a pipe to connect to the WC of the same outside diameter.
3. If you still have the pipe which connects to the WC, then I would suggest:
3.1 Remove the O rings.
3.2 Thoroughly clean and de-scale the part in the photograph and the inside of the mating pipe, without using anything very abrasive. Make sure in particular that the O ring grooves are clean and unobstructed.
3.3 If the O rings are in good condition, coat them in silicone grease and refit.
3.4 If the O rings are perished / flattened, get new ones. You need to measure the inside diameter of each ring (or measure the diameter of the grooves) and the cross sectional size. You can usually get single / two off rings from Amazon or Ebay. I'd buy two of the measured size and two of the next inside diameter down. Grease and fit.
3.5 Fit the pipe and make sure it is supported in a way that it cannot slip down on the O rings.
4. The alternative is probably to replace the flush valve / syphon with one having a more normal termination, and buying and fitting a suitable flush pipe to connect to the WC.

 

[ChrisJP]

The two O-rings no doubt provided an effective seal when they were new. They've now become degraded and that's why the joint has been leaking. Remove one of the O-rings so you can gauge its size and get 2 replacement O-rings. Fit these, smear a little silicon grease on them and refit the flush pipe. If the new O-rings are the correct size then the flush pipe should need a little pressure and twisting to get it into place. That should fix the leak.

 

[Tessa1]

Hi, thanks for responding oldbuffer. The bit that sticks out is one piece with the rest of the cistern outer. So i would have to totally replace the cistern, and getting one to fit the frame would probably be impossible so would probably need to remove the whole item and replace. Which i am hoping to avoid but its kind of looking likely. The flush pipe cracked when i pulled it off but i have bought a replacement 2 inch pipe from screwfix. Would it help to do as you say to clean the rings and then use something like plumbers mate to help seal it?

 

[Tessa1]

Hi Chris, that sounds hopeful, i will give it a try.

 

[oldbuffer]

If you carefully measure the outside diameters of the part with O rings and your new flush pipe, you will probably find a "Fernco" coupling to fit. If this looks feasible and you have enough access to tighten the clips, remove the O rings and fasten the coupler above the upper groove or between the two grooves.