What could be the reason for a ticking noise from a Citroen C3 HDI diesel engine?

It could be one of the injector fire seals.

There is a forum post dedicated to the Citroen C3 injector fire seals here:


and a youtube video demonstrating the sound of a leaking fire seal (ticking or chuffing sound) here:


or, it could be the crank pulley.

There is a video of the sound a worn crank pulley makes and information about the parts required to fix it at