Hi Carlo,
Good question .. For page rank/link juice/ (what ever else we want to call it), to pass and effect a websites ranking within the SERPS can take sometime e.g. if you had a link on a site for 2 weeks then took it down I would be very surprised if this had any effect (good or bad) to the search engine results.
Links need to be present within a website for sometime before you see any effect within your search engine results.
Elements that effect this would be, the engine crawl rates, updating the algorithm etc.
FYI: Last time I checked wiki were using the NOFOLLOW tag, thus not passing page rank
Hope this is of some help