Flush Unit Leak

[chester24]

Hi

Long time reader who has solved many problems by reading the forums.

However, this time I can't seem to find an answer.

I've fitted a new flush unit to a boxed in cistern in my bathroom.

I cannot for the life of me get is to stop leaking where it exits the cistern. I have had to remove the cistern due to access problems to fit the new flush unit. I've tried tightening the large plastic nut by hand and using grips but the moment I put some water in the cistern it starts to leak. I'm filling it just from a tap so it's a quick test for leaks. The plastic cistern looks in good condition (only 2 years old) and the large rubber washer was new with the flush unit.

The flush unit has a large black rubber washer that slips over its thread. Part of the washer then goes through the hole in the cistern. A large plastic nut then sandwiches everthing together.

Any ideas how to stop the leaks?

Thanks

Mark

 

[Burnerman]

Just wondering if the cistern outlet hole is a little on the large side.....the rubber washer passes over the flush valve thread, and then its passed through the cistern hole to receive the backnut.
If the washer is entering the cistern hole then its sure to distort!
John

 

[chester24]

Hi John

Thanks for the reply.

I think the washer is designed to go through the hole. It is a stepped shape.

The smaller diameter part goes through the cistern hole.

Mark[/img]

 

[Burnerman]

I understand what you mean, Mark!
So long as the stepped bit of the washer doesn't protrude through the base of the cistern all should be well, really.
Just examine the plastic thread of the flush valve for cracking, and then maybe consider a smear of silicone around the rubber washer.
Don't over tighten the plastic back nut - although a little plier pressure should do no harm.
John

 

[chester24]

Hi John,

The thread looks in good condition - I can't see any cracks.

The end of the washer does protrude past the base of the cistern.

Looks like you have found my problem. Many thanks.

What's best now - another washer or some silicone?

Mark

 

[Burnerman]

You can use another washer Mark, but obviously it won't need to be a stepped one. The DIY sheds do sell polythene washers that may do the trick, but if you are feeling brave then you could trim the 'step' of the original rubber washer so that it doesn't protrude.
A squidge of silicone does no harm in either instance.
John