My 159's developed a really bad and audible ticking/clicking (tappet??) over the last few months, very noticeable on cold start (seems louder in the car!!), quieting down ever so slighly when up to temperature. Anyway while looking for the source of the noise I noticed a fair amount of diesel pooling on top of the inlet manifold by the swirl valve linkage on cylinder 1. A good 1/2 teaspoon was sloshing about from cold start to operating temp and more appeared to be bubbling from the linkage pivot point. Could this be linked to the tappet noise? Looks bad to me, can't figure out where the leak would be coming from.