I was finally able to replace the belt tensioner in my wife's '02 Corolla CE. It had been making a ton of noise in the recent months and the belt didn't have nearly enough tension on it.
I tried this a few months ago, but wasn't able to get enough clearance and leverage to break the 17mm bolt free. To get past this, I loosened the left engine mount bolt and
softly jacked up the engine with a floor jack. I was able to gain about 1" and barely enough clearance to get a breaker bar and socket on the 17mm tensioner bolt. It's a good thing the engine was raised on the left side too, because the tensioner bolt is so long I never would have cleared the frame.
The engine now runs almost silent, the A/C blows colder, and the lights seem brighter at night. I assume this was because the old belt was slipping and not spinning any of the accessory pulleys correctly.
I picked up the new tensioner from Advance Auto Parts for $89. It was originally $115, but I found a $30 coupon online.