Black sooty build-up around 306hdi injectors

[macaroni]

My sister has a 306hdi (2000my) and there appears to be a build-up of a black, hard, sooty deposit around the injectors, especially 1 and 3.
Any idea what this is and if there is a solution to this?

[wheeler]

its like a kind of carbon build up,your injector seals are leaking,replace the copper seal at the bottom & the plastic sleves that sit in the cylinder head around the injectors,they should cost pennies from a main dealer.if you leave this for too long the injectors will become very hard to remove so do it sooner rather than later.