If you have time, you can test the idler pulley as follows:
- Remove serpentine belt
- Start engine
- Listen for sound
- Install old serpentine belt or replace with new one
If the sound is there after you have removed the serpentine belt, then you know its not that.
If the sound is gone, then you know that its one of the pulleys. As someone suggested, with the engine off, wiggle and turn each of the pulleys to check for play.
FYI: As long as your car has another belt to drive the water pump (which the V6s have), then there shouldn't be any problems with running your car w/o the serpentine belt.
96 Contour SE
Duratec V6 24-valve 2.5L ATX
108,000 mi.
Replaced: crankshaft w/ DMD, EGR valve (clogged), EVR, DPFE, PCV valve, evap emissions hose & tube (cracked), window regulator (broken), LH & RH PCV tubes, UIM gasket (leak), ignition coil
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