Add crankcase pressure?
Steve, manufacturing guys have a saying -" loose, leaks, 'lectrical" are the the greatest issues of production quality.
So - on that . . . while touring a Japanese diesel (truck) engine production line, a curious procedure was encountered. A gallon size can, with a pressure gage was attached to the engines. It pressurized the crankcase and if the engine arrived at the next station, a few minutes away, with a certain pressure it went to paint. If not it, was re-pressurized and sprayed with foaming leak test fluid and repaired. I think the pressure was about 40" of water. I would begin with 20" as we don't know the engines' tolerance for this.
This may work for you, but may not if it is an oil pressure related leak.
Good luck!