I have a 90 geo metro. it started making noises yesterday and after i tracked it down i saw that it was a pully thingy... its on the belt that goes over the cam then under the broken piece then up over the alternator.. i think the bearings in it are shot.. it just rattles all around like its going to snap off at any second... what is this piece called??

What is the broken piece?

Does your geo have air?

Could it be the water pump?

i dont know what the piece is called... its a silver smooth surface pulley.. I know that it is supposed to be kinda springy to help get the belt on...

Ok... i found out.. its the idler pulley.. YAY!! Now! how do i replace it? is it held in by a bolt? clip? nut? and also do i need to remove the big pulley in front of it??

That's not an idler pulley.. That's the timing belt tensioner. Well, you should replace the timing belt while you've got it off. It's held on by the bolt that goes through the middle of it. Also, there's a bracket attached to it. That needs to come off too. I'd buy a manual, a new tensioner, and a new timing belt. The manual will tell ya how to re-time the engine after you remove the timing belt