Start by cleaning everything of old
oil. Get a dye kit that will make the
oil glow under UV light. Crank it up and let it idle. Don't rev it much if it will leak at low RPM. You don't won't wind from the fan blowing the
oil around before you find the leak. If the leak hasn't shown after it is fully warmed up at idle, bump the RPM up just enough to increase the oil pressure to its normal range and check again.