my 1997 f150 4.2 is squeaking at start up and at take offs.It sounds really bad at start up,so i replaced the entire cam pos sensor and shaft driven from the oil pump.The top sensor was in good condition so i reused it,magnet was intact.I did see metal shavings in the cavity below the top sensor,i figured it was from the worn shaft sleave.Well a month later the noise is back,driving me crazy trying to figure out what it could be.I have new engine,oil pump,water pump,idler pulley,alt,etc. I just over hauled the whole truck,and yes the noise was their before the rebuild.I have heard that the starter can drag on the flywheel but it seems to be a longshot.any feedback would be welcome....thanks .....this forum is the best, i enjoy these forums.