I'll second the motion, they are a PITA. My PO had tried to tighten it without loosening the main bolt that the tensioner pivots on and the collar broke. Had to pull the whole thing off to replace the tensioner. The reason they have left hand threads is so that you can screw the nut "in" to tighten the belt.

OTOH, my daughter's Taurus has a very simple spring loaded tensioner, No rubber to deteriorate, no shock absorber, no pointer, just stick a wrench in a square hole & pull it away from the belt. Put a new belt on and release the wrench. Done.

Oh well,

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Norm in NJ
Next oil change at 230,000miles