I am having the same problem on a site that I inherited at a new job.
With me, the post will truncate the entry in a random place, deleting 3/4’s or more of the post content. I have even seen it delete all put the first word of the post title. Again, it happens when you save draft, publish or preview. However, it is not every time. Does not matter the size of the post. It is just random.
I thought it was a php memory limit (google it) issue. But increasing the memory limit did not help. The database entry for the posts looks good and there is nothing wrong with the database. It is most likely related to one of the numerous plugins we have installed.
How many plugins are you using? Which ones? Did you solve the problem?
