MM wrote:
On Fri, 2 Jan 2009 19:41:00 -0000, "Roger Mills"
wrote:

In an earlier contribution to this discussion,
Cicero wrote:

In the light of
this I think you're looking at the wrong place for the fault. The
fault is probably a defective sealing washer at the base of the
siphon unit where it fits through the hole in the cistern. This is a
thin (about 2 / 3mm) plain rubber washer about 2.25" inner diameter
and a seating diameter of 3.25".

In view of the volume of water being lost you may be able to feel
some wetness at the base of the cistern where it joins the pan as
the rubber doughnut might have absorbed some of the leakage.


You beat me to it - I was going to suggest the same thing.

I think the OP needs to re-assemble the syphon and then remove the
cistern from the pan, support it in some suitable way, and part fill
it with water. It should then be possible to see whether water is
coming out from *inside* the outlet tube (leaking syphon seal) or
*outside* it (leaking syphon/cistern point). I suspect the latter.

I should be able to test this by blocking off the large hole (e.g. by
manually pressing the "plunger" part from the syphon with the black
seal on the end tightly against its seating), then pouring enough
water in to cover the boss. If this IS the problem, is that
2.25"/3.25" seal/washer available as a spare?

Probably at a proper plumbing place, but LSX above & below would sort it.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk