td5 injector problem

Hi, is a bit 'of time with my TD5 110 80000km 2004, when the engine is warm, as if there was a ticking injector that doesn't sprays fine, like a "cla cla cla cla" sound .. The problem is that it only happens on idle running only when the engine is hot, when is cold, there isn't any problems ..
Injector loom new and (for now) no diesel in oil,oil level is ok
I've checking all with the nanocom but there isn't imbalance with injectors, everything is normal..

What can it be??

injector seals, ickle copper things

Mean O-rings that are on the injectors, and copper washers that are at the bottom of the injectors?
Why they may be the cause?