Replacing a toilet syphon

[treacletown08]

I am just replacing a toilet syphon and noticed that the original installer put silicone sealant between the cistern washer and the threaded part of the syphon near the hole that goes into the toilet pan. I scrapped the old sealant out but didn't put any new sealant down to replace it. I now have a small leak so I must go out tomorrow and buy some sealant. I have looked at several fitting guides but none mention silicone sealant.

Is it normal to use silicone sealant when fitting a syphon ?

Thanks in advance.

 

[Bosswhite]

Belt and Braces, it stops possible leaks.

 

[Madrab]

In a perfect world and perfect manufacturing processes then sealant shouldn't be required but sometimes there are irregularities in the casting of the toilets or in the manufacturing of the sealing washers so I always put a small bead of silicone around both flat surfaces of the rubber washer just to be sure.
How tight is the big nut BTW?

 

[treacletown08]

Thanks both.

The big nut on the outside has been tightened with a large adjustable spanner and was tighter than finger tight.

I had hoped I would complete this job tonight but it will go into tomorrow.

Thanks again