close coupled cistern leak- help appreciated!!

[shaunyab]

Hi,
I changed a syphon on a stelrad doulton close coupled wc, changed the mounting kit and changed the foam washer. It leaked constantly from the front and back, so tightened up the syphon as much as I could replaced and it still weeped slightly.
So changed the foam washer and put plumbermate between the siphon and cistern, as well as the top of the donut and pan. Still leaked slightly (whether flushed or not).
Changed the donut, trying not to use silicon, but any ideas, I'm giving up the will to live
I really would appreciate some advice!

 

[ALCPlumbing]

Is the washer under the syphon on the inside of the cistern.

 

[shaunyab]

Yes it is, I changed it to a wider diameter, as it did not seem to be sealing well.

 

[Burnerman]

Slightly confused......I guess its the area between the pan and the cistern where the leak is - use a good squidge of silicone over the new doughnut washer. Try to keep the cistern back parallel to the wall - they don't like distortion.
However, this leak would only show when the loo is flushed - if there's water there all the time, its the seal between the syphon and the cistern thats the issue. You need a tight fitting washer over the threads and once again, silicone is your friend!
This design isn't the bolts - through - the - cistern type is it......or the type that has the bracket on the underside of the cistern, captive with the syphon threads?
John

 

[shaunyab]

sorry misread the question, it is under the syphon,not under the cistern

 

[Burnerman]

I see - you have a rubber washer over the syphon threads before passing it through the cistern ceramic, right?
Give it some silicone and it will do no harm. Are the new syphon threads the same diameter as the old one? (Some 1 1/2", some 2" diameter).
John

 

[shaunyab]

Its the normal close coupled mounting bracket with threads external to the cistern.
The surface at the bottom of the cistern is slightly raised, so that is why I changed the washer under the syphon and put plumbers mait under it to try to get a good seal, but to no avail.
The syphon is the dudley (dualtec) adjustable height syphon and the washer I have put on it is tight to the threads.

 

[shaunyab]

you got it in terms of the siphon. Got to admit I didnt check the diameter of the old syphon, but the new syphon is not "too small" for the hole.
If I was to put silicon on the washer, is it best to go on both sides?
Also would this stop the leak between the cistern and pan? or is it a case of siliconing the donut top and bottom as well?

 

[Burnerman]

If the internal ceramic of the cistern isn't flat - for one reason or another - then you'll have a bit of a job with the seal. Examine the old one - is there a heavy ring of silicone present, or a heavier, thicker washer there?
Personally I have no problem with using silicone here - plumbers mait is fine for its intended use, but not for big gap filling.
It wouldn't be the first time I've reused the old washer, either!
John

 

[shaunyab]

GULP......................its in custody with the council..........

 

[Burnerman]

I'd be inclined to have a hunt round B&Q or Plumbcenter I think - just to see what they have in stock.
John

 

[shaunyab]

OK when I go back to the job tommorrow, ill measure the diameter of the hole in the cistern and see what PTS have got any syphons that are larger.
The syphon lokked as though it had never been changed, then diaphragm was gone and the merchants didnt have any replacements.

 

[shaunyab]

Thanks for the ideas! got a bit more to go on.