Roca dual-flush leak

[Johnny2R]

We have a Roca toilet with a dual-flush mechanism. 4 years ago I replaced the dual-flush unit because we were getting a problem with water continuing to dribble into the toilet from the cistern after a flush. The problem wasn't wholly solved, though, as intermittently it would continue to dribble if the 3 litre (lesser) flush was used. I decided to try to address this the other day but I've not succeeded in improving the situation.

A bit of searching on the Internet suggested that the typical cause of these problems was a problem with the seal at the base of the unit, and the way to solve it was to make sure the washer at the base of the unit, and the lip of the receptacle the unit clicks into, were thoroughly cleaned of any limescale and general gunk build-up. I did this, but found to my surprise that the dribble was now occurring after the 6 litre flush was used.

What puzzles me is that this is intermittent in its effect. Sometimes there is no dribble, and sometimes there is a lot more dribble than other times. Given this and the difference between the 3 and 6 litre flushes, it doesn't seem to me that a seal problem would be the cause, as surely this would be a lot more consistent?

Clearly it could be a problem with the unit itself, but given that this would be the second one with this kind of problem, that seems unlikely (unless it's a known design fault).

Any suggestions as to what to look at next would be welcome.

 

[CountryFan]

Check for detritus in the bottom of the cistern. Are you using any toilet cistern blocks? What type of mechanism - does it have tubes or just push rods?

 

[Madrab]

Is the flush valve a twist and remove it out of the cistern version? Do you know the make of flush valve?

 

[Johnny2R]

It's a Roca D2D New Style Dual Flush Toilet Valve, and yes, it's a twist and remove one.

 

[HERTS P&D]

Replace it with a fluidmaster:

Fluidmaster Dual Flush Push Button Valve

Fluidmaster's dual flush push button valve offers you the option of two different flushes. This adjustable flush gives the user control over how much water they use, thanks to the water-saving reduced flush option.The push button valve will fit both 1 1/2" and 2" flush outlets, and it has a...

www.toolstation.com

Andy

 

[Johnny2R]

Replace it with a fluidmaster:

Is that a simple replacement, which can use the same buttons?

 

[HERTS P&D]

Is that a simple replacement, which can use the same buttons?

No, its a cistern off but comes with new buttons.

Andy