I guess something could be worn in the pump throwing the timing off. Replaced an inline fuel filter and the canister fuel filter, along with new fuel lines. The unit is old and looks rough but only has 245 hours on the meter, so I can't imagine the IP ever being removed. I haven't checked the pump timing, but that is next on my list. From listening and feeling, the tapping or knocking seems to be fuel related because you can feel the tapping in the injection lines. Unit runs smooth and clean with hardly any smoke. I think it actually is a bit louder now than before, so maybe the new injectors are spraying harder and possible IP timing being off, just made it worse sounding. I thought it was maybe a bad or several bad injectors causing 'injector knock', so just replaced with new Denso's. Valves have been adjusted twice and they should be in spec. It does have an issue with a loud ticking sound though. Runs good now with no overheating issues. Replaced the head and gasket with aftermarket. It was running hot, so pulled the head and found cracks. I recently acquired a 1989 Sullair compressor with a Kubota V1902 engine in it. I am just wondering if I really do have an issue with the pump that needs addressed or maybe these units are just noisy? Anyone running a V1902 in their tractor that can give me some insight? Thanks for the help! Unfortunately, I can't recall if it made this tapping before the head replacement because I was so focused on the overheating issue.

Kubota v1902 cylinder head