mk6 duratorq 2.o head knoking/ticking noise

[leo s]

hello to everyone,
i have a mk6 transit with the duratorq 2.0 di 100ps engine,i drove this van for the last 35k km,now is 213k km.
it work fine,maybe lack a bit of power,but driving i can ear a ticking noise proportional to the rpm,but slower (maybe same as the crankshaft rpm),the noise is more prevalent when i lift the foot. from the engine bay is more a knucking noise that increase when accelerating.
i've read of problem with cams rocker's roller and hydraulic tappers,and/or injector clamps that get loose.
do you recommend trying to change the oil first? (now semysint 5w30 25k km )

so the point is i if have to take down the cams cover>i need some special tools to put back the injectors in place (with new seals) ?
how i recognise the bad /worn hydraulic tapper?
what are the recommendation/tricks?
as i said in my presentation i 've worked on several engines but never on a ford diesel so go on with the advices!
thank you

[leo s]

hi guys,today i started the tear down,the egr valve was full of black stuff,i think the duct was closed of 50%,also there was a leak between the egr and the inlet mainfold,which i'm going to clean .
after i will post couple of pics

[leo s]

problem was:
one hydraulic tap was stuck,one bearing on a rocker was destroyed.
both on cyl n4,one on the inlet an the other on exaust.
now is rolling on the street again