I see you said you open the oil cap up when running and didn't hear it there,,did you get your ear full of oil
. Jokin aside it sounds like you have a weak lifter or you may have (in the timing chain area) slack side guide broken, I also have a ? for you, What weight oil are using? the reason I ask this is the KA24E has had trouble using 20w50 and never use PTFE stuff in your ride especialy the KA if you will change too 5w30 for winter time and 5w 50 summer you'll notice a big differance and maybe the tick will go away,,also it could be injector making the tick. But sure it's the lifter...Good luck...also Goto this site lot of cool rides.
www.4x4parts.com goto forum do a search on your problem lots info there...