I have a 99 endeavor V6 62,ooo miles which makes grind/rattle for 1 second after starting. It also makes this sound at various other times when driving, generally on light acceleration out of a corner. Only for 1 or 2 seconds. It will only ever do it 2 times when starting, when trying to find the source I have to wait an hour to get the sound when starting again. Does not seem to be a cold start thing as it does it when driving. It seems to be coming from the area down near the serpentine belt i believe. I had previously had it in to the dealer to check on a louder grinding which happened only when turning left. Of course it just stopped doing that when i tried to show dealer, and oddly has very rarely done the left turn grind since.
What do the Cat's sound like when they rattle, does anyone know?