Success!!!! But first the backstory. I’m suffering from some serious health issues, and decided that I could not leave my wife with a 33 year old worn out kitchen. So everything I have done on the project has been with an eye on future use being bulletproof when I’m gone.
Anyway, I did all the testing you guys suggested. AAV on or off made no difference. Removing the P-trap and running water into a bucket yielded better results (disposal is new). I did check for blockage using my Dad’s snake. (Dad was a master plumber and left me all of his tools but none of his skill or knowledge). Pipes were clear. Saw several of you suggesting the rubber splash guard can cause problems, so I pulled the splash guard out and the sink emptied nicely. HUGE improvement. You guys nailed it.
But…as we tested the sink further, it was still belching air quite voraciously. Bad enough that it would splash on the counter. So I looked at the pic of how the pipes run thru the wall and noted that the vent previously teed off of the 90 right before the vertical drop. Replacing that vent with the AAV under the sink was clearly not doing the job. So I made the decision to re-plumb the drain and drop it thru the floor. (I know, you guys are gonna yell at me for this one). I had little choice since I was not going to disturb new cabinets and granite. When I got into the crawl space, I found that I could drop the sink drain literally right into one of the main drain lines (and add a cleanout) with little effort. So I did it. I also dropped the trap a bit and raised the AAV as high as I could. Per this forum I trimmed every other petal off the splash guard before re-installing it, and now the sink drains like Niagara Falls. AND…no bubbles, belching, splashes, etc.
Can’t thank you guys enough for the guidance and help you provided to a first time poster and rookie plumber. Wish I could buy you all a beer. You’re the best.
Paul