Originally Posted by amc49
Probably 15mm. on tensioner center. Lying on back on ground under car, tire off, belt cover removed. Take say a 18 or 19mm. boxed end and hook the closed end over the open end of the 15 to make an extended wrench maybe 16" long. Belt threaded around everything except tensioner. Put 15mm. end of your makeshift wrench on tensioner at around 45 degree angle and turn clockwise to lift tensioner and slip belt under it. Once you have the hang of it you can put belt on in maybe 15 seconds provided it is the correct length.
I was laying on my back, tire off, passenger motor mount off, wheel well liner out and used a 15mm wrench with a 18" length of pipe on the tensioner and could not get it to slip on. I tried the AC pulley, the idler pully, the alternator and tensioner pulley. Not even close to going on, I even had someone try and help. The new serpentine is just a tad smaller than the one I pulled off w/125k on it.