Diesel leak

[pkdj2307]

I have recently fitted a new Stevo head and it all runs as sweet as a nut, Recently i have noticed a tapping noise (not a tappet noise) when you first start up and give a rev, its like a blow from one cylinder (i know its not ) and it goes away after a minute or so, but today i noticed the noise and looked under the bonnet, it seems to come from the nearside rear of the engine but i also noticed a diesel leak from the same area like a constant drip, and a minute or so later it stoped like the noise, any ideas i wonder if it could be a leak on an injector or something like that. it doesnt do it all the time.
any ideas welcomed as i am a muppet under the bonnet, the fitter who fitted the head is first class and a good mate, so no probs there.