Quiet when cold, but when it's warmed up, it "ticks" loudly from the rear of the head. Cam inspection shows nothing odd. Replaced the followers (?) between the cam & valves, pre-lubed, work done to instructions.
If it's the driver's side head I've heard the sound lots. Seems to be related to the EGR tube cooling at a different rate than the exhaust pipe. If it ticks when the engine is running,then I'm no help.
Try running car with valve cover off and make a cardboard shield to keep mess minimal. Watch and
listen to the lash adjuster if ok remove cap for cam
journal and inspect for crack in camshaft. Also keep an
eye on valve movement it could be sticking. Good luck.