The something is the timing chain cover is cracked where the bolt from the head bolts to the top of the timing chain cover,

When the oil goes down that hole and you put a bolt into it without first cleaning it, the oil will hydraulically create a hole in the timing cover at the end of said hole.
I was tightening a bolt in this exact situation and I heard a "pop" and saw a piece of the timing cover bounce off the floor. I picked it up and was like <img src="/forums/images/graemlins/angry.gif" alt="" />

1985 SR5 4Runner
eLocked with Carter Lock
4.7:1 single case
Davez Offroad twin stick