1/2 Bath / toilet not draining properly

[Jwl_Atlanta]

This one is a first for me!! It seems like the black tank plumbing under the 1/2 bath is no longer venting properly. When we flush the water-closet the water does not go down immediately. There is a big-bubble that has to make it way to the surface before the water-closet can empty. Is there a vent or a studor style vent that serves the 1/2 bath toilet? The water closet in the rear of the coach is working fine. Very perplexing.

 

[flyboy013]

There are two vents on the roof. Given the locations, I believe one for each toilet. May want to check to make sure there’s no issue with it. Removal of one screw will allow vent cap to be removed.

 

[Jwl_Atlanta]

I jumped on the roof to look at the vents as suggested. The vent in the rear looks fine, the clear picture is the vent right over the 1/2 bath. Looks like the vent top has been snapped off. Not sure how that would cause the issues we are experiencing but it certainly is not right. Thanks for your advice.

 

[Buster]

I would guess something went down that vent opening and is now blocking the vent from working. Others may have a better handle on this but you may be able to use a plumbing snake to check for blockage and clear it.