Non-flushing Dudley siphon.

[chainsaw_masochist]

I wonder if anyone has any tips re this problematic Dudley siphon ‘11’ (2-part) that is failing to flush.

I expected to find that the membrane would be torn but on inspection it just appeared to be curled upwards slightly towards the top of the siphon. So I removed it, turned it up the other way and reattached it to the flush chamber. I allowed the cistern to fill to the max level and tried to flush but, really, to no effect. I noticed that there was no washer between where the two siphon parts connect so I tried wrapping a few layers of PTFE around the top of the joint to make it as air-tight as possible. But still this gave no joy. I scrutinised said siphon closely but there are certainly no splits or imperfection in the plastic. I have managed to find a washer (taken from another 2-part Dudley siphon) shown in the middle photo that I hope will do the trick and will return to this tomorrow.

Any comments of advice would be most welcome.

Dudley siphon

• chainsaw_masochist
• 7 Dec 2014
• 1

Dudley siphon with washer

• chainsaw_masochist
• 7 Dec 2014
• 1

Dudley siphon membrane

• chainsaw_masochist
• 7 Dec 2014
• 1

 

[Bosswhite]

Throw it away and get a Flapper valve instead !

 

[MeldrewsMate]

Do you mean o-ring when you say washer?
Make sure you lubricate the o-ring on assembly (soap will do if you don't have silicone grease) to effect a good seal. Remember, this is a syphon, air getting sucked in will stop it working.

 

[chainsaw_masochist]

Yes, sorry, I do mean o-ring. That’s a good point about silicon grease so I will take a tub with me. What may be the problem is that the two parts of the Dudley siphon are held together by a yellow pin and this may be less effective in achieving a good tight seal (when a bit old) rather than the types which have a screwed thread. Thanks, M'sM.

 

[MeldrewsMate]

What may be the problem is that the two parts of the Dudley siphon are held together by a yellow pin and this may be less effective in achieving a good tight seal (when a bit old) rather than the types which have a screwed thread

No, the o-ring doesn't have to be clamped hard to form a seal, it merely has to be the right size and not distorted. So make sure the mating surfaces are clean, and there is a small resistance felt when assembling the lubed part. The pin does not have to be tight, just tight enough that it doesn't fall out!

 

[chainsaw_masochist]

You're right, M'sM, it now works fine so a big thanks for your input.

 

[MeldrewsMate]

Flushed with success.