Cistern bolt hole irregularly shaped - causing leaks

[Skipper]

Hi All

I've had to replace my cistern bolts recently as they had become rusted and were starting to crumble and cause leaks. After replacing the bolts, I've been getting a consistent leak out of the right side bolt. I took the bolts off to check if I did anything wrong and it seems like the bolt hole on the right side is not properly round, so it seems like the rubber washing isn't sitting perfectly flush which seems to be causing the leak.

I figure I need to find some way to plug that gap caused by the shape of the bolt hole, but I've had few people tell me I should avoid silicone/putty if possible. I'm at a bit of a loss about what to do at the moment. When I removed the previous bolts there was a mass of some sort around the right bolt, so I'm guessing whoever installed the toilet initially solved the issue with a sealant of some sort.

Right side hole

New bolt that I fitted.

Would appreciate any advice on what I could do/use to solve the problem.

 

[ShaunCorbs]

How tight are you tightening it ?

 

[Skipper]

How tight are you tightening it ?

I tighten it as far as it goes by hand, then give it 4-5 more rotations with a spanner. That manages to get the leak to about 1 drop an hour.

 

[ShaunCorbs]

Bit of clear silicon should sort it

 

[Timmy D]

You could get a diamond coated needle file and reshape the hole. However, that seems hard work. As Shaun replied, bit of silicone.

Or my preferred, CT1 as it sticks in the wet.

 

[SimonG]

I silicone the lot. If the cistern comes pre assembled I take it back apart and silicone on the inlet valve, flush valve and cistern bolts.

Easier than pulling it all apart later because theres a leak.

 

[cjg]

plumbers gold on all seals, just a light smear seems to work as it sets under water,
no leaks up to now,(fingers crossed now i"ve said that)