Oil Leak in 1999 Camry

I have a 99 Toyota Camry with 160,000 miles. I am not sure the actual size, but the motor is the 4 cyl. I was the second owner of this car, and it has been leaking oil from somewhere on the side of the motor where the timing chain housing is for a year now, it leaves a small circle of about 6 inches each day underneath. I have had the cam seals replaced twice, new timing chain 3 times cause the oil is leaking inside the housing and causing the chain to go bad, and it still leaks. I have had two mechanics to tell me they cant find the leak, they are guessing about the cam seals. I had them replaced again this week because he swore it had to be the seal, but it is leaking worse now, I bet a qt a week. What can it be if it is not the seals? The motor itself is in great shape they told me, so it is not a crack.