waste reducer boss leaking

[FRANKIEJUNIOR]

The 110mm waste pipe comes straight down from the ustairs toilet into the ceiling void,then branches to the left running into an internal soil stack,boxed in corner,and out to drain. As well as branching to the left in ceiling void it also branches to the right approx a foot or so, where a reducing boss is fitted to take the 40 mm bath waste pipe.
The old boss leaked and i changed it for a new one. It leaked when the toilet was flushed,just a slight drip but enough to do ceiling damage over time. The leak came from the fit of the boss into 110 mm pipe, and not the fit of the bath waste pipe into boss. Is there silicone i can apply like i was thinking of tec 7 as there doesnt seem to be a burr on the inside dia of 110 mm pipe and the leak def doesnt seem to be running from anywhere else that i can see. All help appreciated.

 

[muggles]

Go to your local plumbers merchants and ask them for a tube of gap filling adhesive, that should cure it

 

[FRANKIEJUNIOR]

Go to your local plumbers merchants a
nd ask them for a tube of gap filling adhesive, that should cure it

Thanks,would bathroom silicone sealant do the trick then or maybe it doesnt stick to rubber

 

[muggles]

Rubber? Is there not a plastic outer to the boss going in? Something like this? http://www.bcprofiles.co.uk/soil-pipe/soil-pipe-40mm-boss-clip-110mm/prod_132.html

You should be able to glue round the plastic outer. Bathroom silicone might do it but it takes much longer to go off than GFA, I'd say you'd have to stop using anything connected to the stack above the leak for a good 36 hours to be on the safe side, and even then it might not seal, GFA doesn't need anywhere near that long.

If your boss isn't similar to the one in the picture, any chance of a photo so I can see what your situation is please?