Well, I'm no expert on every possible configuration of the 300tdi, but your tensioner looks nothing like mine. Mine's exactly like the diagram. I have mine where I can get a good picture at the moment. I'll try to post up a picture tonight if no one else chimes in first.
------ Follow up post added August 16th, 2010 10:16 AM ------
Wait a second...did you assemble that tensioner? It looks like you might have the tensioner pulley mounted to the wrong hole in the plate. It should be in the offset hole and the other three should be concentric.
8-track, gun rack, spittoon, gimbal mounted beer buoy, blah, blah, blah, blah......