Close Coupled WC - Sealant

[dunc21]

Why do the instructions for fitting a close coupled wc say NOT to use any jointing compound when installing?

Last time I fitted one (15 years ago) it took me ages to stop it leaking out of the cistern/pan rubber joint - ruined my new cushion floor.

Now have a new one to fit. Can I use silicon sealant around the rubber before mating?

 

[kevplumb]

which rubber?

 

[brumylad]

these things are a pain I agree, especially cheap continental tat. If I have to resort to using sealant I usually use plumbers mate. I think they advise against sealant because of the potential for movement between the pan and the cistern(which should usually be fixed to the wall) every time someone sits on the bog ?

Also the chances are the solvents used in any kind of sealant or joint compound will degrade the rubber over time.

 

[dunc21]

Ok Brumy - thanks. Looks like the advice is to stick with the instructions then. The suite was from Wickes - I think it is uk made but nothing actually says where. I do have some plumbers mate that I used for the sink and bath so maybe I might smear a bit round the rubber seal at the pan connection - maybe not!!?

The cistern is boltes through from the inside onto the pan and uses rubber washers here too. Was going to assist those as well, but maybe I should just rely on the rubber seals.

Oh dear!

 

[shaggy]

Dunc, I have come across a leak from where the bolts that go through the bottom of the cistern that couple it to the pan. The problem was caused by the pan being fixed too far from the wall and when the cistern was fixed back to the wall it was pulled at a slight angle and the rubber washers did not seal. In that case, rather than move the pan, I made some spacers so the cistern could sit upright but I did use silicon round the washers to make certain.
I personally don't think that silicone will affect the rubber seal as the solvent evaporates very quickly and just leaves rubber.

 

[dunc21]

Ok thanks Shaggy. I am surprised this topic doesn't come up more often- I did a web search and could find nothing on it.

I think i might use some plumbers mate now rather than my trusty silicon sealant, as I have to get the old one out and the new one in and usable within the day - otherwise the family will be jumping up and down!

I will put a bit inside and outside the bolts through the cistern and a bit around where the rubber seal connects to the pan.

 

[dunc21]

Well - just spent the afternoon installing new close-coupled wc. After the advise here and a similar topic (see here ), I decided to use the Hylomar which I bought from a local car accessory/parts shop (Hylomar Blue).

I used it as directed and assembled the cistern to the pan (bolt through the cistern type). It is leaking at the moment! . As the water is gradually seeping from around the cistern base, I guess it is one of the bolt/rubber washers leaking.

This brings me to another point then - just how much are you supposed to compress he rubber cone washer? I take it that the cone point goes into the hole in the cistern with a washer over the flat end. Tightening the bolt with the washer and nut on the underside compresses the cone into the hole. But the instructions just say "until the rubber washer is compressed" - but by how much.

I was a bit loath to tighten too much for fear of cracking the cistern, but I did tighten a good bit, so the rubber was bulging out from beneath the washer. Should I tighten until I cannot tighten any more? or what???

This means I have to take it all apart again - if I have to I have to, but only once... please. My back aches.

Any suggestions?

 

[taydo]

It could be leaking from the base of the syphon?

I always use silicon sealant on all the washers it is not worth the time and effort putting them together without and then finding out they leak.

 

[dunc21]

well Taydo, I guess it could, but again I did follow the installation instructions - Hand tight, then half a turn - it was quite tight. Again applied with Hylomar top and bottom.

I was wondering if perhaps I put a spanner inside the cistern on the fitting bolts and tightened whilst holding the wingnuts under the pan, whether this might seal it (if it is those and not the syphon base) or would this draw the nuts under the cistern into the top of the pan holes and damage the pan???

If I do have to dismantle it and reseat - do I have to remove the Hylomar? leave it and put fresh on? buy new rubber fittings?

 

[jasy]

GO TO ANOTHER FORUM

 

[kevplumb]

bu**er off back to general chat you

 

[dunc21]

ok - it seems clear then that nobody knows the answers to my conundram - or at least don't want to tell me.

I left it a day wrapped in a rag to soak up the seepage, but I guess it's time to take it apart and have another go.

 

[shaggy]

Dunc, it is possible that there is a defect in the cistern. The holes are cast into the porcelain and not machined so there may be a leak path through a badly made hole that the rubber washer cannot seal on it's own. I would have a good look and if it's really bad then get a new one. I have taken wash basins back when the waste didn't sit right and that was Armitage.
I would expect to be able to seal the washer with silicone though, but leave it all day to cure.

 

[DP]

Use of sealing componds for motors can cause rubber to creep resulting in leaks. If the makers intended the sealing to be effected by addition of sealants, instructions would have told you. Never known a gasket (which the rubber is) to pass if both sealing surfaces are clean

I would check cistern internal face for defects or cast fangs.

 

[kendor]

Silicone sealant can lose adhesion if moved, you are better off using a smearing of silicone grease applied to the rubber washers /gaskets before assembly.