Need advice on venting 2nd floor bath

I have a second floor bathroom that has the typical tub, toilet and sink. Problem is there is no vent that I can see and the tub wont drain unless the toilet outake pipe is open (toilets removed). Sink seems ok, toilet and tub drain within a foot into the same line the sink is about 6 feet away and ties into the same drain line. So, it goes tub drain, tie in sink drain, tie in toilet drain (smaller pipe 1 1/2 brass I think for tub and sink-- and 3 inch PVC for toilet for sure) emptying into 4 inch PVC to CI.

I am planning to use an AAV to solve this problem. See the pictures for a better idea of what I am facing and my plan to correct it, am I on the right track? The AAV only needs to be higher than the trap right, I mean even a couple inches would work, right?

http://www.flickr.com/photos/50039121@N07/4651116005/


http://www.flickr.com/photos/50039121@N07/4651780852/in/photostream/

http://www.flickr.com/photos/50039121@N07/4651800760/

suggestions, thoughts, advice?

Thanks

IF the fixtures do NOT drain unless you remove the toilet, you have MORE than a vent problem and an AAV would be useless to cure it.

hj said:

IF the fixtures do NOT drain unless you remove the toilet, you have MORE than a vent problem and an AAV would be useless to cure it.

Click to expand...

I don't understand what else could be the problem? I fill the tub with the toilet on and the tub doesn't drain (no air can get into the system), I remove the toilet (letting air in) and the tub drains fine. What else do you suggest could be the problem?