This is the project that never ends....

My advisor was in town briefly yesterday, and managed to stop by the office in the sub-24 hour period he was going to be in the correct time zone. He's finally started reading the manuscript that's been sitting on his desk longer than I'm comfortable admitting. Foolish me, I was hoping this would be a sign that the associated project might wrap up sometime soon.

Despite the fact that the funding for this project ran out over a year ago, and I'm supported by a completely different project (i.e., my alleged thesis topic...), half of our brief meeting time was spent with him talking about all the things he wants to do next for this project. Note that this project was supposed to only be for my first summer, to get me acquainted with molecular dynamics, and help the post-doc working on it wrap up his papers.  So a project that was originally intended to last 3-6 months has now taken two years, and the papers *still* haven't left the building.

I'm reluctant to simply announce that I'm done with this particular branch of work, because I'm sitting on three more manuscript drafts, and I would like them to make it out the door sometime before I manage to. On the other hand, the longer I'm working on this first project, the longer it's going to take me to get fully entrenched in my supposed thesis project. It doesn't help that it takes some serious shoe-horning to try and get both of these projects into a thesis together in any sort of semi-coherent fashion.

Any suggestions for how to tell my advisor that I would like to work on my thesis project full-time?