Thermostat help?

[DeanMoriarty]

I replaced the tensioner today. Oddly enough... and I'm still crossing my fingers on this one, it didn't make the clanging noise after I changed it... Just seems like an odd fix to me, so I don't want to get my hopes up. The thing was in really bad shape though, the back had come partially off and the spring was working it's way out.
How long can I expect to let the alternator and AC pulleys go? Will they start squealing before the bearings go or should this be done now?