Can't get Fluidmaster cistern outlet to seal properly.

[TyrannosaurusTex]

Can't get Fluidmaster cistern outlet to seal properly. Its a soft-ish plastic tank and hard plastic housing for the flush mechanism and large rubber seal which goes on the inside of the tank. Should I be using silicone?

Thanks

 

[ALCPlumbing]

Generally you don't need silicone but if you can't get it to seal then a bit won't hurt. Are you using grips? Hand tight isn't enough.

 

[stardanny]

Make sure surface of cistern where it sit is clean of scale, dirt and muck.

Check there is no hairline crack in cistern, around hole.
Are you using cone shape washer on tail between valve and cistern?

Tight it with flat surface spanner, don't use grip with teeth.

Daniel.

 

[TyrannosaurusTex]

Thanks very much for both responses. I've used a wrench to tighten half a turn and then tightened a bit more each time I check for leaks but no joy. The wrench I have used does have teeth, its the only I have which is large enough for the job. I think I'll give the silicone go.

Thank again.

 

[TyrannosaurusTex]

Sorry, that should say I tightened to hand tight and then used a wrench to tighten half a turn.

 

[TyrannosaurusTex]

re. the washer, I'm using one that came supplied with the cistern. This is quite wide and flat and ribbed. It also has a small rim that sits inside the outlet hole at the bottom of the tank. To my mind, I would think that as the nut tightens, it pushes up against the rim which in turn might compromise the seal against the inside of the tank. As it came supplied, then I suppose its supposed to work.

 

[longdogs]

re. the washer, I'm using one that came supplied with the cistern. This is quite wide and flat and ribbed. It also has a small rim that sits inside the outlet hole at the bottom of the tank. To my mind, I would think that as the nut tightens, it pushes up against the rim which in turn might compromise the seal against the inside of the tank. As it came supplied, then I suppose its supposed to work.

Not everything that is supposed to work, actually works. It sounds like the washer is a bit too soft/stretchy for the job and over tightening it would pull the washer out of shape. If you look inside the cistern you can normally see the misshapen washer. If silicon is used inside the cistern, it might make it worse because it becomes too slippery when tightening

If you want to try silicon, I would suggest that you apply it underneath the cistern, around the hole (see pic below) and don't over tighten.

View media item 76246
If that don't work you might have to obtain a new washer.

 

[TyrannosaurusTex]

Thanks Squeaky, much appreciated.