Buzzing pump and knocking engine

Just been recovered after losing power on the motorway, the car was running fine, 98 300Tdi EDC, then a strange buzzing, ticking noise and lost power.

Idles rough and knocking sound, maybe cause running on 2 or 3 cylinders, not sure, loud buzzing from location of injector ump when power switched on and also when engine running

Any ideas of what to check

sounds like solenoid buzzing at back of pump-if not solenoid,pump will buzz with air in it,fit clear pipe between filter outlet and injection pump inlet and look for bubbles-no bubbles allowed.

Thanks, I found the cause, after removing front cover and checking timing and clear pipe to check air in fuel, removed the rocker cover and the middle rocker shaft stud, that goes through to the rocker cover had snapped in the middle and pulled out of the alloy head.

Looks like the valves where not opening enough.

I had some threaded bar that fitted, is that OK to use it seemed to tighten up OK, or must it be high tensile?

Cheers