Leaking toilet waste pipe - solutions?

I've just noticed that my next door neighbour's external waste pipe from the loo is leaking - it's just a drip at the moment but I'd like to help fix it for them as they are very elderly. The pipe is cast iron, a bit rusty and I'm guessing original, so that would make it about 100 years old.
I've not taken a really close look, but is there any way I can seal it eg with mastic? How do a get a good seal on a wet and probably crumbly pipe?

Otherwise I guess the only answer is for them to get it replaced with plastic, but I'd like to try and help them avoid this expense.

Thanks in advance

SB

what you need is a 1lb club hammer

seriously tho its probably the joint thats leaking
you will need to dry it first then plumbers mait or sealant

You're right kevplumb - to hit you on the head!!

Thanks for tip, will pop out and get some gunk (technical term that)
SB

PS Are we the only two saddo's with nothing better to do on a Tuesday afternoon? I'm supposed to be revising for exams - what's your excuse?

"Fernox LSX" is a sealant, similar to clear silicone, that bonds even to wet surfaces. It comes in little tubes for about £4. There are all sorts of similar things for sealing burst pipes etc that will probably do the job.

If you go to your local plumbers' merchant they will be able to sell you all kinds of esoteric gunk that will stick to anything and seal anything. Word of advice, buy some disposable gloves and wear them whilst applying it. Don't worry about looking like a mincer, anything gunky will make your hands VERY sticky for hours.... you will be glad you wore the gloves later on when you reach for the toilet paper.

I really must advise the merchants to be the place to go, they will have a better range, better advince and it is my experience that anything to do with sealant is cheaper there than in any shed.

Everyone has their favourite gungey stuff for jobs like this and I'm the bastard that uses denso tape