Cistern flush pipe connections

[Frank Stacey]

Just discovered that the flush pipe on a concealed cistern is leaking. Fortunately no serious damage has occurred. This is a system installed

40 years ago and has not been touched meantime. The leak is at the flush pipe to cistern join. The flush pipe enters at an angle. I propose to replace the flush pipe with an L shaped one which will align the join. However I don't know how the connections at each end are constructed. Can someone explain? The cistern end has a plastic nut but I cannot see how that is sealed and cannot locate a replacement part in any of the plumbing catalogues - well screwfix & toolstation actually. Flush pipes seem to be 1 1/2" diam. How is this join sealed? The WC end seems to use some form of "gooey tape". What is this and how is it used.

Your collective advice is much appreciated. Frank

PS My earlier "urinal flush mechanism" problems [nothing to do with an aging prostate!] are well on the way to being solved thanks to your replies. I just have to remove a stubborn 22mm olive on the existing pipework!

[A Plumber]

The cistern end of the flush pipe will have a rubber "O" ring on it to seal. on the other end, you need a plastic connecter that goes into the back of the pan boss. fit this onto the flush pipe then press into the boss at the back of the toilet boss. or there are rubber ones that go over the boss at the back of the pan.

[The Medway Handyman]

You can buy a complete kit from a decent plumbers merchant.

scroll down about 3/4 of the page to 'Flushpipe' and below it 'Flushpipe to Pan Connectors'

The top end uses a tapered rubber seal & compression nut just like a compression join or elbow.

The botom uses a push in 'Flushpipe to Pan Connector' - the finned one sems to be more common IME.

Things may have changed in 40 years :-)