I had a similar problem with updating the cache, and I fixed it with the MagicNoCache
extension (
http://www.mediawiki.org/wiki/Extension:MagicNoCache). This extension creates a
magic word (__NOCACHE__) that disables the cache for that page.
You can find more info on purging your cache at the Wikipedia:Purge page
(
http://en.wikipedia.org/wiki/Wikipedia:Purge).