topology problems when previewing smooth

[Anonymous]

Hey Guys,
I have this Problems very often, and don’t have a good way to fix it. The Problems only shows when previewing smooth. Somehow the two faces aren’t connected, which I was able to show on the second image when adding an edge loop and moving it slightly.
I made sure to merge all vertices, so that there are not two vertices on top, or close by each other.
Sometimes I have this sort of problem, when the normals are facing different directions, but that is not the case here.

Like I said this is not the first time I have this Problem, and normally I fix it by deleting the faces, and rebuild the geo around the error. I was hoping there is a better solution.

[cavescholar]

Hello, so what happens once you are in smooth preview, hit the page up key, you can keep doing this to preview higher steps, then just use page down button to go down in previews. Even though you are doing a merge maybe turn up the threshold for merge distance. The other thing is to set Display > Poly Details. Then box select the area and see how many verts are showing selected. If it is connected but preview looks like it is not, I would say it is normals or non-planar geometry. If you connected 2 pieces of geometry maybe delete the history then try smooth preview. If you are adding an edge loop but it is only splitting the one face, then it is not a solid geometry. Maybe just grab one vert at a time and try to move it to see if it takes all the edges with it. If not, then that is the problem, it is not connected. 

Lastly, maybe CLEANUP tool will solve it for you, non-manifold geometry option selected. 

Good luck!