I have a 2003 Jetta TDI ALH. It’s making a ticking noise which seems to be coming from the valve cover. I just replaced the camshaft and lifters hoping that would solve the ticking. Sadly it did not. I thought maybe there was a pre ignition from a injector so I cracked open each injector one at a time at idle but no change to the ticking. It’s quite a loud annoying tick. It ticks at any rpm. Any ideas of what to look at next?