can you leave the water run down the pipe? it will either give away it location, or blow out the plug. could save you a lot of work.
I didn't mean to hijack the thread, but since nobody else is commenting on the Expo. . .
The poop pipe runs out the back of the house , and used to end about 10 yards away , just at the fenceline. When I got the place, I thought it was a bit short for my taste, so I ran a 100 ft length of corrugated drain pipe on top of the ground off the end out into the pasture. At the end of season, I went out to move the end of the pipe, and there was no pile of solids out at the end. The other end was bone dry too. Inside the house, everything was working okay. so I figure the break is in that 10 yard run. It's clay pipe, and it' shallow, and I can see where the grass was growing a bit greener despite the drought this past summer. That is where I intend to dig.
The funny thing is that we had almost an entire year's worth of sewage just disappear. It didn't burble up in the yard, it did not come back in the house. It did not come out the other end. It just . . . went somewhere. I tried running a lot of water down the pipe, but nothing showed up. My guess is the clay pipe sections have separated and I'll end up replacing the whole 10 yards with plastic pipe. There is five feet that I may have trouble getting to; it is under the utility shed I built on the back of the house.