Easiest Way To Replace Siphon Diaphragm On Ancient Cistern?

My shop has a very old high-level cistern, made of rubber I think. The supply and flush pipes are lead.

The diaphragm is split, as the chain takes a lot of pulling to flush. Most siphons need to be completely removed to replace the diphragm, but I don't really want to disturb the lead flush pipe, as it has many layers of paint, and hasn't been disturbed for decades. I forsee many more problems.

I notice that the plastic (i think) siphon fitted has 3 screws near the base inside the cistern. If I remove these screws, can I split the siphon and not need to disturb the joint under the cistern?

TheOP said:

My shop has a very old high-level cistern, made of rubber I think. . Most siphons need to be completely removed to replace the diphragm, but I don't really want to disturb the lead flush pipe,

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• TheOP
• 9 May 2011
• 1

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Try the screws but don`t hold your breath . you might find though - that the syphon plunger will come out without removing it all - even undoing the flush pipe isn`t really a problem - the paint will just flake off the lead . nothing else

by replacing the toilet

Sorted. Removed the 3 screws, and the top comes off the siphon. Turns out it's a Dauntless siphon for a wellbottom (rubber) cistern.

New diaphragms are available online, they're the circular ones, with a circular hole in them that fits over the siphon tube in the cistern.

Many thanks.

Thomas Dudley Dauntless Rubber Well and Rubber Line (now superseded by the Tri-Well) cisterns usually had D shaped syphons and so needed a D shaped washer, not circular.