Pigletjohn help please, leaking cistern on flushing.

[Smugandproud]

We have a cloakroom toilet that is old and a strange set up.
However it was working fine but would just randomly flush sometimes.
Two weeks before Christmas and a houseful of guests dh decided to replace the siphon.

Now the toilet is leaking from the pipe leaving the cistern to the bowl.
The plumbers merchants have gone through the set up thoroughly so I know he’s connecting the pipes correctly.
It only leaks on flushing but it’s quite a lot of water.

Any advice gratefully received.

Could be the doughnut washer if it is close coupled
or if the cistern is separate it will be the seals / washers around the flush pipe at the bottom of the cistern or where the flush pipe goes into the back of the pan
new washers and seals on any of the above are in expensive and should sort it out

We bought all new washers etc.
This is what's baffling.
I think its maybe not tight enough.

From your description, if there is a pipe from the cistern to the pan then you have what's known as a low level suite.
Can you tell if the pipe leaks from the top or bottom? If it only leaks on flushing then it's just either the top or bottom connection.

If it's the top then there should be a washer that sits around the pipe behind the large nut and tightens in place as the nut is tightened. If it's not sealing properly then a few turns of ptfe tape around it may help.

Where the pipe connects to the pan then there around be a large flush cone either rubber or plastic and pushed well into the back of the pan. Make sure the flush pipe is pushed well into the flush cone.

As for the intermittent self flushing, then I'm not sure.

Thank you. It leaks from the top.

Google ghost flushing. As you have a leak then this will trigger the toilet to flush once the water gets low enough. Must be an incorrectly fitted / tightened part. PTFE tape could help or silicon sealant depending on where the leak is (don’t use on moving parts, only to seal cistern).