So I just finished a in frame rebuild on my 4.0 everything went well and it runs great with good oil pressure.

The only issue is the rear main seal is leaking. I did everything by the book I oiled the seal, used rtv where required and torqued to spec. I was reading somewhere that rear main seal might leak for a while when new until it swells? Is this really a thing?
Areas where I checked for leaks include oil filter, oil filter adapter, valve cover and oil pan. No leaks from those places and I verified the bolts are tight.

Thank you.

 

Never heard of them needing to swell. They should seal up right away. Sure it's not the back of the pan leaking?

 

Just out of curiosity, what is the brand of the seal and gaskets you used?

 

Mine stopped leaking immediately.

Are you SURE you didn't put the top half in backwards? You didn't damage the seal groove in the block or crank when you drove the old one out?

 

I guess I could’ve put it in backwards. If i did scratch the crank then I guess it will never stop leaking now. It was an engine tech brand from my re build kit. I guess I’ll drop the oil pan and give it another shot. Does fel pro make a good RMS? My local parts store only has that brand.

 

I only use Fel Pro seals and gaskets and have never had a problem with leaks...in my opinion they are the best you can buy.

 

Thanks I will go get one and hopefully I can fix this.

 

I prefer Fel-Pro as well, and if they have two versions get the more expensive one. Very true for the valve cover gaskets - spend the $35 instead of $9 and get the nice reusable silicon rubber one instead of cork that will leak within a few years.

 

I put a fel-pro in mine as well.

 

Felpro or Mahle only for important seals.

 

I know it's been awhile but I finally got time to work on the Jeep. I re did the rear main seal with a Felpro and so far no leaks.
Thanks everyone.