OK, this is something that is bothering me. Coming home from work on tuesday, my fathers grand marquis suddenly started knocking. 87, 5.0L, the usual package. But the odd part is, that it doesnt seem to knock till the motor has been run for a few minutes. Pulling the plugs turned up a Badly fouled plug on #7 cylinder. all of the others are fine. However, the knocking is coming from the bottom of the oil pan, near the back, making it a safe bet that its a rod bearing. But what bothers me is that it would just start knocking unprovoked. the car is regularly maintained(by me), the oil was up to range, the pump puts out 40psi on idle, anyone have any ideas what caused it? or is it just a fluke?