hey all its been a long while since last being able to be on here.. 2 jobs is NOT your friend for free time.. anyways i have a few questions reguarding my 2002 f150 with the 4.2 v6 and 5spd standard trans...

1st is i have a slight rear main leak... i say slight now and i know it will eventually progress to worse.. my question is it is a 1 peice, do i have to drop oil pan and crank to replace or can i do it with only loosening oil pan, or not even loosening anything up and just doing it with the flywheel off?

2nd comes with the territory with the first, i keep a real tight eye on my oil levels from the fact of the rear main leak, and the lowest i have ever dropped was about a quart low.. but here and there i hear what seems to be lifter rattle.. is there any adjustment to fix that or are they set hydraulic lifters and only repair is replacement? oil pressure idiot gauge never moves, naturally (working on installing a oil psi gauge, anyone know where i can find pillar pods designed for this truck lol)

3rd but not least is i get a intermittent p0420 catalyst system below threshold.. ive talked to several people from the counter guys at parts store, to guys that have worked in and ran garages for years, and i get mixed answers, its split about 50/50 that it is bad cats... or a bad downstream o2 sensor... i personally think the o2 makes more sense being intermittent but want another opinion or 12 from maybe someone who has had the same issue...


i apologize for the book but like to include all i can for a better analysis..
and i thank any and all help and hopefully will be able to repay the help in the future here

 

The rear mane seal is in the back of the motor.
You will need to drop the trany to replace it.
Not sure about your other problems. ):

 

Thank you.. but I already know of the position and know the trans would need dropped as well as the flywheel removed... just not sure if I can pull the old one and install the new one without unbolting the oil pan or crank... thanks for the input tho...