29 Jan 2010
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United Kingdom

I am fitting a 'new' (well, brought new some years ago, but only now fitting) close coupled WC Pan and Cistern (Manufacturer: Olympus, Model: Cayman) and am struggling to connect the two.

The units came with a foam connecting washer (110mm diameter) and the WC pan has a 100mm diameter recess at the back to take the washer. I have tried to connect the two using the foam washer and cannot get a good seal, despite a number of attempts. Also the foam washer does not look like it will give as good a seal as a rubber washer, but I would be interested in peoples thoughts on this.

After doing a bit of Googling is seems that this problem (i.e leaky foam washers) is a common problem and most people end up getting a rubber doughnut washer to replace the foam one, which is what I have done. The best one I could find was from Screwfix ( I also tried my local Plumb Centre). See attached picture of the two washers and Pan.

The problem is that the rubber doughnut from Screwfix is 110mm diameter and the recess in the pan is 100mm. Can anyone advise on whether the rubber doughnut will work (the guy from Plumb Centre said the doughnut will push into the recess under weight of the cistern) or whether I need to find a 100mm diameter doughnut to match the recess? The rubber doughnut really does seem too big to ever fit the recess.

Any hints on positioning the doughnut, cistern and pan (to ensure the washer (either foam or rubber) will stay flat and in position while connecting up) when connecting the pan and cistern would also be appreciated.

Many thanks


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I didn't mention in my post that the washer you have suggested was the first one I brought, but decided not to use it as it appeared to be too small when placed inside the pan recess, which has an inner diameter of 3" while the washer outside diameter is only slightly larger at 3 1/4". I thought the washer may get pushed down inside the inlet hole of the pan.

Also, the washer has to be stretched to get it over the large back nut on the cistern, whereas the other, larger one I brought is hex shaped (See pictures in first post) and fits well over the back nut, making me think that washer was more suited.

I have attached a few new pictures showing how the washer you have suggested looks on the cistern and pan.

Have you used this type of doughnut washer successfully on similar sized units ?

Thanks for your help.


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Frank, expect it to sit proud as it will compress and don`t be tempted to add silicone.
There should be a seal inside the cistern ,between the bottom of the flush valve and the cistern . is it in place ? The foam washer that came with the w.c should be fine. Are you sure the leak is actually coming from that joint ?
steve32 - thanks - just checked the screwfix washer and it is in fact a 2" one that I brought. I will hunt around for a bigger one as the seal it give seems good. However when the cistern is on the Pan using this washer the cistern ceramic is resting directly on the pan ceramic, so the washer is obviously too thin unfortunately, as well as slightly too short in diameter.

Justpumps - thanks - as per above, the 2" doughnut washer is definitely not sitting proud, but the foam one is. Just can't get the foam one to sit evenly in the recess, which may be a cause of the leaks. See below.

terryplumb - thanks - Yes the seal is in place, just checked. Perhaps in hindsight I could have tightened the back nut slightly more when fitting, but as this seal is also foam (approx 5mm thick) I did not want to squeeze it down too much when tightening the back nut. I am not 100% sure that the leak is coming from the foam coupling washer, but I do know the foam washer is not bedding down evenly, as it seems to always pop up just as I lower the cistern on to it. However last time I did it (and connected the supply pipe and flushed) I think it was a quite good fit, but I suspect there may have been a crease or compressed area on the foam somewhere. I am wondering how the foam can produce a good seal even when fitting correctly, but it sounds like you have confidence in the foam washers which is interesting / good to hear. Must be just my skill in fitting it. Any suggestions on how to do this ?

Thanks for your help chaps.
1. Make sure the big nut is tight.
2. Use the seal that came with the WC
3. Fit seal onto the big nut / underside of cistern ,and lower onto pan .if its a loose fit on nut, support from below whilst lowering cistern to pan. The long screws will help location .
4. When tightening the wing nuts that hold cistern to pan ,do them evenly ,both at the same time if you can ,so even pressure is applied to the foam washer.

I have a feeling that you may not have the valve ( flush )tight enough to the cistern. And get rid of the PTFE tape on the fill valve thread. Its totally unnecessary .

Thanks. Much appreciate your advice.

Only just looking at the forum again since last weekend, and will be trying to get the toilet working today.

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