John Stumbles wrote:
On Sun, 09 Dec 2007 13:25:42 -0800, dog-man wrote:

My toilet was leaking slightly from where the flush pipe goes into it
whenever we flushed the toilet.

I renewed the plastic bung that the pipe goes through and also the
pipe as it looked a little short to me.

It is still leaking!

There is only the pipe going through the plastic bung that fits into
the hole at the rear of the toilet. No washer or seal of any kind.

Should there be something else there to stop the leak?

No, if the surfaces are clean and the flush pipe goes into the bung far
enough (and straight) it should seal OK,

By far enough, do you mean as far as you can push it?
I'm about to install a cistern to marry up with one of the old 2 part WC
bowls where the soil pipe is straight down rather than out the back (so
changing it would be a pain). I can see the cistern has to be positioned
accurately in terms of height for the flush pipe to be straight but I
wonder how much leeway there is in the length. Is it usual to shorten
the pipe if the cistern is closer to the WC?
I'm trying to gain a couple of inches behind the new cistern to put some
insulation on the wall, which I reckon I can get with a slimline plastic
job.