Well the only logical hypothesis for the tappet noise would be either "clogged" or smudgy or dirty or name it how you want tappets because of oil residues or tappets wear that would be a cause, as you said, of an aging pump, which is highly unlikeable I guess and very rare, they rarely fail and when they do, you'll certainly know it haha. As I said, I added a Lukoil tappets additive which should clean the tappets and should be really good as I've read, but not even the slightest improvement to be heard. At this point it's still a guessing game, once the things are stripped down then I can see what's what. I ordered the timing tools and then I'll get to it, I hope it's just the secondary belts aging related wear causing the ticking and not one of the pulleys, especially the ones with the damper as you said, because they cost a small fortune
