Sealing toilet cistern doughnuts

Andy Dingley

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Apr 29, 2011, 6:26:52 PM4/29/11

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Close-coupled cistern. I've just replaced the syphon and I've got leak
problems. There are no bolt holes in the cistern, it uses a steel
plate beneath as a doughnut compressor.

How many thin rubber washers should be used? Obviously one is beneath
the syphon on the inside. Are others required around the steel plate,
or should the doughnut alone be sufficient?

The Medway Handyman

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Apr 30, 2011, 3:37:54 AM4/30/11

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Should be just the doughnut. If the seal between the siphon and the
cistern is leaking you will have a constant dribble - if it only leaks
when you flush its the seal between the cistern & the WC - the doughnut.

Usually one rubber washer between base of syphon & hole in cistern - I
always liberally LS-X that.

There are two types of 'doughnut', one is square section & t'other is
rounded over on the bottom face. You have to replace like for like.

You did fit a new doughnut? They never work if you re use them.

Also - make sure the bolts are threaded all along their length - some of
the 'kits' available (Homobase) have partly threaded bolts & you can't
tighten them enough.

If a new doughnut don't not sort it, Plumbers Mait is the answer. Don't
use silicone, it just makes a mess.

HTH

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

Nick Leverton

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Apr 30, 2011, 5:23:21 AM4/30/11

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In article <j%Oup.41906$o81....@newsfe28.ams2>,

The Medway Handyman <davi...@blueyonder.co.uk> wrote:
>On 29/04/2011 23:26, Andy Dingley wrote:
>> Close-coupled cistern. I've just replaced the syphon and I've got leak
>> problems. There are no bolt holes in the cistern, it uses a steel
>> plate beneath as a doughnut compressor.
>>
>> How many thin rubber washers should be used? Obviously one is beneath
>> the syphon on the inside. Are others required around the steel plate,
>> or should the doughnut alone be sufficient?
>
>Should be just the doughnut. If the seal between the siphon and the
>cistern is leaking you will have a constant dribble - if it only leaks
>when you flush its the seal between the cistern & the WC - the doughnut.

Probably teaching my granny, but make sure the new syphon is nicely
centred and flat. I had no end of trouble with leaks last time I
replaced one, because the silly cramped cistern only just had room for
the new syphon and a Torbeck valve, and each time it got flushed the
syphon pulled a little further off centre. It tested OK each time I
re-fitted it but the leak just got worse. Eventually had to replace
the Torbeck with a good old ball valve so the syphon could sit straight !

Nick
--
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"The Internet, a sort of ersatz counterfeit of real life"
-- Janet Street-Porter, BBC2, 19th March 1996

Andy Dingley

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Apr 30, 2011, 4:45:13 PM4/30/11

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On Apr 30, 10:23 am, Nick Leverton <n...@leverton.org> wrote:

> Probably teaching my granny, but make sure the new syphon is nicely
> centred and flat.

I think that was the trouble in the end. It's a nasty old '70s cistern
& pan (double syphonic!) and has a vast hole in the bottom of it. The
syphon had shifted sideways a bit and there was no good contact at the
edge of the rubber washer.

I put it back together with a spare O ring dropped loosely over the
syphon to hold it central. Now it seems OK and leak free.

Now I just need to wait for the cement patch in the wall to cure
before I can screw it back onto the wall properly. The thing has been
on and off so many times that the old wooden plug has fallen apart and
the hole has broken out bell-mouthed 8-(

Jim K

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Apr 30, 2011, 5:37:08 PM4/30/11

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altogether now :-
"resin anchors and squirty foam, topped off with one hit filler as
necess, wet finger finish to suit"

Jim K