the tearing could be many things. mechanical ectropion ("loose" eyelid) is the more likely scenario if you are over about 40 years old (please dont be offended if you are not 40+)
if it is mechanical, its going to be difficult to stop. a surgical procedure is really the only option, and even then it may or may not help.
if it is NOT mechanical, then Rx anti-allergy eyedrops may help, even if this is not related to allergies.
you definitely need an exam to look into the "blown pupil".
http://www.wiseorb.com/articles-review-478-T-DRY_EYES%3A_THE_PROBLEM_OF_THIS_TIME%2E.htm