Re: How to change idler pulley of 2001 sable?
The belt tensioner is the complete tensioner assembly. The tensioner pulley is just the pulley wheel on the tensioner. I had to replace the whole tensioner assembly on mine, because it was locked up so it wouldn't move with the spring.
I used a regular socket wrench (I think it was a metric size) to remove the idler pulley, and a Torx (star-head) size T-50 to remove the tensioner assembly. It required a lot of force to remove the bolts, so much so that I was worried about breaking off the Torx head bolt. But it finally came loose with a pop and came out ok.
If your tensioner assembly still rotates freely with the spring, then you can probably just replace the tensioner pulley wheel if it's bad.
While you're at it, also check your water pump for bearing tightness and noise. It should rotate freely and not have any wobble when you try to wiggle the pulley. Likewise check the alternator and airconditioner for noise when you spin their pulleys.
Hope this helps.