I have a 2003 f150 4.2. Have had rear main seal changed 3 times and still have a leak. A little history on the truck. First two seals leaked right away. Third one garage added a sleeve because of little nick from removing old seal. This tme lasted 2000 miles no leak. Now its worse then ever. What do I need to know or look for?

 

im not sure about that truck but see if it has a breather and check to see if its pluged it sounds like your diff is building up to much pressure and is blowing the seals

 

If there is aleakage problem it is needed to be replaced as soon as possible....because making it replace each and every time cost you more than the newer one...so its better to replace..contact to any authorised dealor and ask what can be done.

 

I'm having the same problem with my 2001 Explorer Sport with a 4.0 V6 SOHC. I have over 242,000 miles on it. After review with 3 different RMS and a dozen mechanics, we've come to the conclusion that there is slack in the crankshaft that's causing oil to pass through the rear main. When I originally took it in, there was only a seep. Now, a small puddle build on the ground whether running or not. I also noticed while working closely with the last mechanic that I am beginning to hear a slight intermitten knock at the bottom of the block which seals the deal with the crank theory. I'll be getting my long block rebuilt soon.

My suggestion would be to start it up, watch the drips and keep an ear out for tapping/knocking loud or quiet at the bottom half of the engine. If you do hear something, take it in to get mic-ed by a mechanic. That will tell you what's going on and where. Good luck! Hopefully it's something else.