You can try using sea foam in the engine oil for 15 minutes before oil change, I do that to all my vehicles except for my diesel truck, I used to own a 2000 Isuzu Rodeo 4x4 and they are famous for having that tick, once I did a few oil changes like that and changed to Rotella diesel oil the problems went away. Now I own a 1999 Montero and have done all the basic maintenance and timing belt, etc. no tick on mine but I do use the sea foam at every oil change and Rotella diesel oil still and have over 230k on mine and no issues yet, no tick.