About six months ago my 02 4.0 made that horrible "I have no oil" tappet / lifter noise for about 2 seconds when I started it up one morning. It was short enough time and the fact that it had never happened before that by the time my brain noticed it, processed it and realized what it was, it was gone. It worried me but it was so brief that the more I thought about it the more unsure I was that it was what I thought it was.
It was about two months later it did it again. In the next several months it did it maybe twice.
So far in the last week it has done it three times . The sound is without a doubt that ' motor with no oil ' sound. I change the oil regularly, it only has 38k miles on it , the weather / temperature seems irrelevant to the occurrence. It is brief, only a second or two seconds, and only when starting it after it has set all night , never after it has set all day (while I'm at work). Oil pump going bad ? That would seem like the obvious answer to me but then something about the fact that it only does it after it has set 12 hours or more... thought I would ask around before I waste time / money replacing the oil pump.
Farrell Christeson