So I just rebuilt my 2.3L/ 4 cylinder on my Ranger. Since then I have had to replace the rear main seal about 4 times. I cant figure out why it keeps leaking. Pretty much all of the valves and sensors were replaced. I cleaned out the oil separator and replaced the PCV before reinstalling the engine. All the vacuum lines seem to be free and clear of obstructions. Today I am replacing the EGR Vacuum Solenoid(totally overlooked replacing that to begin with). Any other ideas on what could be causing this? Thanks for the help.