Oil leak from too much crank case pressure?

[Fancy89]

Hey guys i was wondering how yall set up your PCV system and oil catch cans? I have had a persistent oil leak from my 4.9L stroker engine. I am currently on my third oil pan gasket and rear main seal. This latest go around, I bought the moroso oil pan gasket to go with my moroso oil pan. I also installed a new fel-pro rear main seal, i clocked it, added a tab of RTV on the end of the gasket, i added anaerobic sealer and then torqued the bearing end cap to spec. I cant get this oil leak to go away! my engine builder was saying its possible from too much crank case pressure because i have such a large stroke and displacement from OEM. On my current set up i have a 3/8 hole drilled in my back PCV and kept the front one stock. I then added the two sides of the PCVS to a T and ran it straight to a moroso oil catch can with a air filter on top. I am curious if i need intake vacuum to help relieve pressure? I don't think i have engine blow by, i have a trusted engine builder who has been rebuilding engines for decades. I am curious if you guys have ran into this problem yet or if i just got the one faulty oil pan lol.

[mpgMike]

A picture is worth a thousand words. It's a bit difficult to envision what you're describing. My catch can is off the rear (restricted) port. It then goes to a 2nd "catch can" with pot scrubbers and -- water. It's a water vapor injection system as well.

PCV6.png

[Fancy89]

so my back PCV is drilled out.

[Gorilla]

The Felpro RMS gaskets have a reputation for leaking. Frankly the 4.0L in general has a reputation for leaking. I'd had a leaking rear main in my 4.0L since about 3 years after it was built (I bought my TJ new). Decided to swap it for a Felpro last spring. Went 1000 miles with no leak. And... now it leaks worse than new.

The consensus in the WranglerTJforum world is that Mopar is the RMS you want and doing some specific things in prep seem to help with getting a good lasting seal.
https://wranglertjforum.com/threads/rea ... t-4-0.826/

Added to this, some have started to run a bit of paper towel with degreaser or brake cleaner through the upper channel 3 times.

While RTV is required on the corners of the pan seal, it is not recommended on the RMS. Only anaerobic sealer should be used and sparingly in a specific way. In turn the engine should not have oil added to it and especially not run for at least 24 hours while the seal cures. Several folks have said after their 2 previous attempts, slowing down and doing this had finally resulted in a leak free seal.

Hope that helps. I've got this on my re-do list very soon.

[mpgMike]

To add to the great advice Gorilla just offered, I developed leaks from my valve cover and oil pan about 2k miles after a total rebuild. I went back over all of the bolts with a torque wrench and found most all of them were either loose or at least under-torqued. I'm once again leak-free.

[Gorilla]

I also see from converting your displacement to L, that you may be running a 4.060" crank. If so, people have had to clearance the oil pan with that crank to get it to work. Could this have caused some distortion to your pan, resulting in a bad sealing surface?