I am in the process of trying to find out whats wrong with my tensioner. I have removed the radiator, loosened the 3 bolts on the water pump pully, removed the fan and the belt. I took the bolts off the water pump pully expecting the pully to just pull off. Somehow its stuck on there. I tried tapping it with a hammer and block of wood and i loosened it up somewhat but it still won't come off. What in the world could be holding it on there, corrosion? Any ideas on how to extricate the pully? Its a 95 c280. Also when i turn the pully i hear a little squeeking from the water pump. Does this indicate its on its way out?

First off why are you removing the water pump pulley? Secondly the water pump usually fails by leaking. It is hard to assess a squeak over the internet, but if it is not loud and the pump turns smoothly, I would leave it for now. It's such a big job to change the pump, it won't make much difference if you have to pull it apart again.

Good luck,