Silent Running Toilet eluding capture

[slocombe9]

I have three toilets in the house. Two have been "silent running" for a while now (constant trickle of water leaking from the cistern into the bowl).

They are identical Ideal Standard units as shown in the picture.

I successfully fixed one of the toilets by replacing the seal at the bottom of the flush unit.

But the second continues to run, despite:

• Replacing the seal at the base of the flush unit
• Swapping out the flush unit with the third (always ok) toilet
• Swapping out the flush unit holder that screws into the base of the cistern
• Tightening the screws that hold the cistern onto the bowl as much as possible.

The offending toilet I dismantled and reassembled a year ago as part of a wetroom installation. Perhaps it's something to do with the screws that hold the cistern to the bowl? When I did this work I felt confident that it was done correctly.

I'm out of ideas. Anyone got any suggestions?

 

[ShaunCorbs]

Is the base plastic smooth eg where the silicon / rubber seal mates ?

 

[slocombe9]

Is the base plastic smooth eg where the silicon / rubber seal mates ?

If you mean the screw fitting that holds the base of the flush unit, then, as mentioned I swapped this, as well as the flush unit with another toilet that wasn't leaking, and the leak stayed with this toilet. In any case, I did check that the surface that mates with the seal at the base of the flush unit was completely clean, flat and free of any debris/scale.