Can't Get Seal to Cistern Fill Valve

[RBZ5416]

This is doing my head in.

Had a slight leak from the feed to the Fluidmaster fill valve. So just as i did around 8 years ago, popped it open & the fibre washer was shot. Replaced it & re-assembled but it won't seal. Pulled it apart & replaced the washer with an O-ring & that won't seal either. Pulled apart again with a fresh fibre washer & still leaks. Significant leaking past the thread, not just a weep.

Only thing that makes any kind of sense to me is that the plastic shank on the fill valve is somehow worn, but I can't see any nicks or other damage. Any suggestions before I bite the bullet & buy a replacement valve with a brass shank? That would be in hope rather than expectation.

The inlet connector has a collar for the washer to sit on & the washer should seal against the end of the shank.

 

[oldbuffer]

1. Usual issue is that the connector nut has been cross-threaded onto the white plastic shank. Only realistic cure is inlet valve replacement.
2. Other possibilities:
2a. Remains of old fibre washer lodged in connector nut.
2b. Leak coming from cistern and only appears to be from connection. Resolution is to tighten white plastic nut holding valve into cistern.

 

[just pumps]

https://www.googleadservices.com/pa...jGhr_B9YH2AhVUolwKHRqhAoIQ9aACegQIARBr&adurl=
Could try one of these if you dont want to replace the whole fill valve.

 

[Deleted member 292770]

get one of those soft tapered bung type seals.
if that fails then the cistern is cracked.

 

[Deleted member 292770]

one of those

 

[RBZ5416]

1. Usual issue is that the connector nut has been cross-threaded onto the white plastic shank. Only realistic cure is inlet valve replacement.
2. Other possibilities:
2a. Remains of old fibre washer lodged in connector nut.
2b. Leak coming from cistern and only appears to be from connection. Resolution is to tighten white plastic nut holding valve into cistern.

I've had the valve out to inspect the mating surface & the backnut came off smoothly, so definitely no cross-threading. Unless the brass nut is cross-threaded, which seems unlikely against a plastic shank.

No debris present.

Can actually see the water pushing up past the thread, that's just gravity fed so not even mains pressure.

Could try one of these if you dont want to replace the whole fill valve.

Not sure how that would help as both existing contact points would remain in play. But the feed is solid copper anyway, so an extension would introduce an angle at best & more likelihood of cross-threading.

get one of those soft tapered bung type seals.
if that fails then the cistern is cracked.

The leak is definitely past the thread & not from the cistern.

Just off to Toolstation for a new valve.

 

[Deleted member 292770]

I've had the valve out to inspect the mating surface & the backnut came off smoothly, so definitely no cross-threading. Unless the brass nut is cross-threaded, which seems unlikely against a plastic shank.

No debris present.

Can actually see the water pushing up past the thread, that's just gravity fed so not even mains pressure.

Not sure how that would help as both existing contact points would remain in play. But the feed is solid copper anyway, so an extension would introduce an angle at best & more likelihood of cross-threading.

The leak is definitely past the thread & not from the cistern.

Just off to Toolstation for a new valve.

make sure it has that type of seal, you wont go far wrong.

 

[just pumps]

I've had the valve out to inspect the mating surface & the backnut came off smoothly, so definitely no cross-threading. Unless the brass nut is cross-threaded, which seems unlikely against a plastic shank.

Not sure how that would help as both existing contact points would remain in play. But the feed is solid copper anyway, so an extension would introduce an angle at best & more likelihood of cross-threading.

Just off to Toolstation for a new valve.

Err you what? Only one contact point would remain the other would be new brass.
Introduce an angle and increase the chance of cross threading - How?

 

[RBZ5416]

Err you what? Only one contact point would remain the other would be new brass.

If the issue is with the plastic shaft then that will still be connected to inside of the extension. If the issue is with the feed connector then that will be connected to the tail of the extension. Hence both of the original contact points would still be in play.

Introduce an angle and increase the chance of cross threading - How?

I probably should have said that feed pipe runs horizontally with an elbow connector to the valve. Extending the shaft would take the feed pipe beyond 90 degrees & create a slight angle to the valve. Hence the increased likelihood of cross-threading.

New valve with brass shank fitted & fingers crossed, it seems to have done the job.

 

[just pumps]

If the issue is with the plastic shaft then that will still be connected to inside of the extension. If the issue is with the feed connector then that will be connected to the tail of the extension. Hence both of the original contact points would still be in play.

I probably should have said that feed pipe runs horizontally with an elbow connector to the valve. Extending the shaft would take the feed pipe beyond 90 degrees & create a slight angle to the valve. Hence the increased likelihood of cross-threading.

Sorry dude but you're wrong on both cases.
Good luck with the new valve