Hello i have a 2002 ford explorer sport 4.0 4x4 and im replacing the timing chain guides and im having a issue, on one guide i can get to it looks like i have to take off the bottom part where the oil pan is. i was wondering in order to take it off do i have to take off the oil pan first? or can i leave the oi pan on? are there any screws in the oil pan that i have to take off?