Leak on rad valve stem

[diytryer]

I've just noticed a small leak (very small) on a rad feed pipe, its where the valve is screwed into the pipe, it looks like its been over tightened to the point its split the top of the pipe (very slightly)

what can I use to seal this small leak bearing in mind it has a small amount of water coming through it?

[greenday]

make good the joint

i.e redo it