Help in Getting Outline

[servarus]

Hello, quite new here, and desperate for some answer. Sorry if I misplaced this thread.

I used this model for my university project, and then I imported it to AutoCAD 2010.

The problem is there's quite a number of lines missing in plan view, though I can still redraw from what I have. Front view is much worse. Only lines here and there. I don't really know what is causing this problem. Exporting the model to AutoCAD lags it like hell, so redrawing is very hard.

So I am wondering if there's a setting or tweak for me to get only the outline of the model. I need it for my section view.

I hope I can get some answer. Thanks in advance.