Oil Leak

[70challengersix]

Well, after a few issues, I am up a running strong with my 440.  The engine is freshly overhauled installed and started for the frst time.  During the breakin, I am developing fairly high oil pressure - somewhere in the neighborhood of 80-85 psi at 1300 rpm or so.  Here is the issue, I have a leak, that I think could be coming from the rear main. Its just below the tranny/engine interface and since the engine is dry externally (no sign of oil), it may be coming out of the bellhousing with the rear main being suspect.  So, I plan to drive the car a little and see if it may clear itself.  I will get under the car this weekend to confirm the leak is within the bellhousing/engine interface, but was curious if maybe it is possible that the seals could "swell" over time and limit the leak?
Is there any way to fix a rear main seal without pulling the engine.  Its tken me 5 years to get this car together, and I am not excited about tearing it all back apart again.

There is absolutely no leak when the car is turned off and only occurs when running.

[72cudamaan]

No seals don't swell, yes you can change the seal while the engine is in the car and
there is a possibility the rear cam plug is leaking. That would only leak under pressure usually.

[Chryco Psycho]

the oil sender is directly above there , make sure that is not the problem .

[Moparal]

There is a few other things to consider.  New engine?  Ring seat and blow by past the rings. Got a pcv valve? the right one?  If the engine has crank case pressure no seal will hold. Also it is kinda rare to have a seal leak , but the serated part on the crankshaft wasnt designed for a rubber seal, they used a rope seal. But the side seals in the rear main seal can seep oil. Also the oil pan if tightened to tight. If it is a 4 speed car, the input shaft on the trans seal could be leaking. Diagnostics is the hardest part of mechanic work in my opinion. Once you find the problem, fixing it is nothing more than nuts and bolts to a gear head. Don't rule out the valley pan gasket or oil send unit, or valve cover gaskets

[Chryco Psycho]

if the rear bolts on the oil pan into the seal cap are too long you can also break the seal cap & cause a leak

[70challengersix]

Thanks guys,

I will look into it more today.  I know its not coming from top (oil sending unit) as the engine is dry on the outside from that point.  I assume the rear cam plug referred to is the freeze plug, I will check that and get a new pcv.  I will remove the plate at the bottom of the tranny and look around inside the bellhousing/engine interface to see if its wet with oil in there.

If thats what it is, I hope I can do a seal change without pulling the engine.