basement drain gurgling

Hello,

I've recently had some sewer smell coming from the basement. There are 2 inground traps, 1 at washing machine utility tub, the 2nd about 30 ft away with a capped cleanout next to it. Last week the when flushing the toilet, I could hear both traps gurgling. I had a plumber snake the drain at the washing machine tub (which now drains MUCH faster), and he also snaked through the main cleanout. We flushed the toilet a few times. All was good. Its now a week later, and I started to smell the odor again. As a test, I removed the cleanout cap and reinstalled it with a little silicone. It seems the smell is gone, but when I flush the toilet the trap at the washing machine gurgles again. If I remove the cleanout cap, the gurgling does not occur. Almost forgot, I can fill the utility tub next to the washer, and let it drain, and it goes down extremely fast, the water doesnt backup at all. Is there a chance there is a vent issue somewhere ? Or does the main still have a clog ?
THANKS

If your house was built during or before the 70s you may have a root intrusion problem between the house and street...if after the 70 it may just be a build up stoppage...either way I would recomend that you call a plumber that does drain cleaning..they will be able to fix your problem...

It almost sounds line a vent issue. Do you have a building trap? If so, Is the breather in tact or visible?

below is a drawing of the basement layout




This is the main waste line with all pipes coming in. This morning, I removed the white capped PVC line that you see with the red arrow. (used to be the washer drain, old ladies had the washer on main floor as to not use the basement stairs) So when I removed that cap, and flushed the toilet, the trap at the utility tub still gurgles if the CO is closed tight. The only way I can stop the gurgling is to open the CO cap enough to allow air to escape. But everything flows and drains good in the house wheter the CO is capped or not. I looked inside the main waste line, when I removed the PVC cap the best I could. Its obviously lined with gunk on the walls, but it seems there is a sufficient opening going up to the vent pipe. Would the next step be filling the vent pipe with water from the roof ?

Sorry the pics are not showing on my end. I can't see them

no, not yet

your yahoo e-mail isn't going to show...

Upload it as a graphic file attachment.

Ok now the pics are up

Other than the stack vent (3") there are no other vents visible. You need to make sure the pipe petruding through the roof isn't plugged with a birds nest or any other foreign object. I particularly never liked those T's that have multiple connections on the sides, but I guess they would have been the norm at the time the house was built.

There are no CO caps anywhere, other than the clean out under the utility tub trap. . The cap that you see is just that,..... a cap

Start by checking the vent through your roof and then start working yourself into the attic space to see if any other vents are visible.

where are your inground traps? I assumed your problem was underground

I agree it could be because of when the house was constructed. But I would call plumbers and see what they say. A cesspool service suffolk county here on long island that I'm friendly with told me that this problem comes up in our area sometimes also.