My toilet seems to have developed a leak where the flush pipe joins the bottom the cistern.

However the joint only leaks when the toilet has been flushed. Once the cistern is full again the leak stops.

Any ideas on how to fix.

Rod Clarke, October 2005

take a look at cisternfittings.co.uk they have everything you need and also friendly advice..

andrew scales, January 2014

Could be the rubber seal on the flush pipe is at fault or the ring nut has come loose. re-tighten.
It could also be the larger nut holding the syphon in the cistern, re-tighten.
Still leaks! then replace the rubber seals on both.
If its just coming from the flush pipe then sometimes smearing a generous layer of vaseline around the rubber seal works.
Rob

Rob, November 2005