I have a 2001 Toyota Tacoma, V6, that was driven approximately 3 miles
without any oil in the engine. After reaching the truck I filled the
engine with oil, started it, and let it ran for a while. Since all
appeared to be fine, the truck was driven for approximately 30 miles.
After reaching the destination a slight noise was noticeable on the right
side of the engine. After letting the truck set for two hours, it was
driven, on the return trip, the same number of miles. While driving the
noise got a little louder. The truck set overnight, so when it was
started, the next morning, the noise developed into quite a loud tapping.

I thought the noise was coming from maybe worn lifters or camshaft lobes,
but there was no miss while the engine was running. After pulling the
value covers off, I measured the camshaft lobes and found that they were
all within tolerance and the lifters looked fine.

Please advise on what is the possible problem or problems.