In our finished basement, there is a black pipe with a clean out valve. The valve does not seem to be leaking, and its not wet around the pipe above the tiles of the floor, but it seems to be oozing from under the tiles, (this is a basement floor, with concrete under the tiles) It doesn't happen all the time, sometimes days can go by without any water, it also has a bad odor, maybe sewer gas? What do you think it could be caused from? We have cleaned the air vent, it wasn't that.

You're not going to like what I have to tell you. You've described a ABS or black cast iron clean out. It should have a threaded clean out cover and not a valve. It sounds like you may have a partial clog in the main and a break somewhere in the drainage system. Is your system on city sewer or are you on a septic tank? If on a septic tank the tank could be full and needs to be pumped. When the main loads up with water it backs up out of the break. If the water coming up from the tiles is back away from the clean out then the break's inside the house and to repair it you must open up the cement floor. However, you may be able get away from that by snaking out both the house main and the sewer from the house to the street. It's worth a shot. Let me know what you come up with. Best of luck, Tom

I have a septic tank, and I just had that pumped out a few days ago, He did say it was pretty full, but did not think that would be the cause.
What would cause a pipe in the concrete to crack? What do we do about it?Do you think that since it is not oozing any other place, that the crack is near where its coming out? My husband snaked it all out, and did not seem to find any clogs. He said he felt one area that seemed to be clogged, but he is not sure if it was a curve or turn in the pipes.
What would be our next move? :confused:

Is your line ABS or cast iron? He doesn't know if he hit the clog or a bend in the pipe? He's going to hafta push through whatever's stopping the cable and snake from the house cleanout to the septic tank. You have to be absolutely sure the line's clear and without any breaks. Do you notice the leak more after running the washer? How far under ground is the sewer line? Can you dig next to the house and check the soil for moisture? It's for sure that somthings's loading up the line and hitting a partial blockage and backing up. You have to get the line clear and if you can do that you may find your troubles are over. Cheers, Tom

Do you think I should try not using the washer for a while and see if it stops? What about the dishwasher? Do you think it would be worth it to try to stop using them and see if the leak stops?
Why would they put the pipes in the concrete? Is there some place I can read about this?
My brother who was here from Denver when we first found out, says the pipes that we can see are the ABS, not the cast iron, but not sure about down farther.

I can answer your question about the ABS pipe encased in concrete. Just before the sewer line exited your house the plumber installed a fitting on its back with a pipe extending through the slab for a clean out. I don't believe that not using the washer will prevent leaking because ALL the discharge from your house passes by that cleanout. The washer just dischages with more force then the other fixtures. I repeat, to be certain you will have to force a snake through from the clean out to the septic tank. To further check you should dig next to the house down to where the sewer exits and check for moisture. If you find none then the leak is in the house under the slab. Let me know what you find. Regards, Tom