You need a Thrump_rrr tensioner. I don't like the oil on that idler pulley in your pic, was it over spill or from the 5 min running? What kind of pulley is that?
That's grease that came out of the bearing. Damn, I should have just waited and started a thread in tech - not gettin' the lookers over here and I know zip about bearing specs/jargon/etc...